Why has the Centeron pulley disappeared on many Shimano rear derailleurs? I have no idea if it's only some mechs or all nowadays but a while back I noticed its absence. Always thought it was a clever design to aid alignment when things were slightly out of adjustment. Derailleurs still go out of alignment despite changes in design such as actuation ratios etc. so why the change?

For anything over 6/7/8-speed the chain and cassette are now so narrow that any amount of side to side float from the sliding Centeron pulley would not allow indexed shifting to change gears.

In my experience newer generations of chain and cassette seem to be better at holding in one gear under pedaling load with the derailleur visibly misaligned too, with just a little noise but no slipping, where older and low-end systems would grate and skip teeth.

As mentioned in a joking-but-not-really-joking comment the bearings in the jockey wheels will become pseudo-Centeron sliding bearings as they wear. When this happens it makes single gear shifts impossible with a single indexed click - you then have to double-click the shifters to change one gear, or triple-click for two gears as the slack is taken up.   (this also happens with other bits of the drivetrain worn)


Effect of helmets and other impressions of the bike rider on driver behaviour? Are there any studies on the effect of helmets and/or other impressions of the bike rider, on driver behaviour?

Has anyone collected their own data on things like this?

Has anyone noticed any other slightly unexpected oddities like the two I observed bellow?

Recently I had to ride back home on a road down a 10km route which I've travelled many times before, but without a helmet, the difference in driver behaviour was very noticeable... I got a lot more space, didn't have a single car overtake me dangerously close (though a few were certainly still illegally close).

I've noticed similar differences when i'm sort of practising riding skinnies by staying dead in the middle of the lines at the sides of roads (this seems to give drivers FAR too much confidence to act dangerously... I was already worried about this particular test after just one day, I was actually interested in getting hard data riding on the lines vs normally vs unstable and wobbly (against number of cars coming dangerously close (based on video)) unfortunately i only got as far as anecdotal evidence that skinny practice on road lines is dangerous as hell, that normal riding seems much safer and that wobbling about unstably does seem to make you safer from drivers, but it's easy to get carried away. Then as I was practicing skinnies some twatwaffle hit me with his wing mirror, putting me off balance, scaring the shit out of me, and ending my desire to gather data, while increasing my desire to keep away from asphalt in general.

Those experiments ended, and I never thought about it much till the helmet incident recently... I'm certainly not intending to do the no helmet experiment myself, so I was wondering is there any real data for this kind of thing, or any other interesting phenomenons to do with driver and cyclist etc?

Seems there are studies showing both:

2008 Walker study - "Cars get closer to cyclists wearing helmets"

https://www.scientificamerican.com/article/strange-but-true-helmets-attract-cars-to-cyclists/
http://news.bbc.co.uk/2/hi/uk_news/england/somerset/5334208.stm
https://www.sciencedirect.com/science/article/pii/S0001457506001540

  when Walker wore a helmet drivers typically drove an average of 3.35 inches closer to his bike than when his noggin wasn't covered.

However in https://helmets.org/walkerstudy.htm  in 2013  this was refuted.  Also https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3783373/

  After re-analysis of Walker's data (2006), helmet wearing is not associated with close motor vehicle passing. The results, however, highlight other more important factors that may inform effective bicycle safety strategies.

I don't have my own data, merely subjective anectodes about how much room I receive when riding a tandem, or towing a 2-wheel trailer, or the two times I trialled a recumbent and had cars crossing the road to go around me. I'm NOT that wide.

Locally, milk tanker drivers are awesome at passing with extreme room. They don't slow down from their permitted maximum of 90 km/h but they will give me a full lane of passing space where possible, which is 5-6 metres.


Alfine 8 vs Alfine 11 Gates CDX chainline? I'm considering replacing a Shimano Alfine 8 hub with a Shimano Alfine 11.

The bike has a Gates CDX belt drive, and I want to retain the same belt, chainring and rear sprocket.

My understanding is that the Gates belt drive is very sensitive to correct chainline.

Assuming the chainline is currently correct on my bike with Alfine 8 hub, can I substitute an Alfine 11 without having to adjust the chainline?

Thanks

The obvious place to look is Shimano's specifications page, but that does not appear to give chainline.

A bit of googling found a couple of pages that give specs for the Alfine 8 and 11.

This page simply states the Alfine 11 chainline is 42.7mm.

This page gives a more complete picture for Alfine 8, giving chainline for 2 sprocket mounting positions and several models. Seems that 42.7mm chainline is achievable on SG-C6000 and 6010 models.


How do I align my front brake disk with the caliper? I have manual Avid disc brakes.

I took my front wheel off like I've done hundreds of times. When I put it back on the wheel is aligned properly with my fork, but the disc presses against one of the brake pads. This causes a lot of squeaking when I simply roll the bike and a ton of friction that will eventually destroy the brake altogether. This really isn't making sense to me other than the possibility that the caliper just isn't aligned properly, which seems practically impossible because all you do is screw it in.

I have tried adjusting the sensitivity of the brakes to the point where the problem pad is off of the disc. Then the other pad is so far out that I have 0 braking power when I try to apply it (other than a little friction from the problem pad). Can anyone please help me?

It's not that unusual for a front brake to move a bit when taking it off and reattaching it. This is due to the small amount of space between the fork ends, axle, and QR bolts. The fork flexes a bit when you put the wheel back on. That small space that it moves is a lot relative to the clearance that disc brake pads have. That's likely why your brake pads aren't lining up again.

Now, the fix (NB: the following assumes that by "manual Avid disc brakes," what you mean is "mechanical disc brakes."):

It sounds like you're overlooking a couple of points of adjustment. There is a red knob/wheel that adjusts either side of most Avid mechanical disc brakes, one on the inside and one on the outside. There are also caliper positioning bolts (CPS, the "S" is for system) that move the entire caliper perpendicular to and directly above, the bolts that attach the caliper to the frame.

The basic procedure to properly align your brakes is to:

Loosen the bolts perpendicular to the mounting point so that the whole caliper moves easily.
Completely loosen both of the red pad adjustment discs.
Tighten the inboard pad adjustment knob until the rotor is centered in the caliper.
Tighten the outboard pad adjustment knob until the brake is clamped onto the rotor. This ensures that the caliper is centered on the rotor.
Tighten the CPS bolts.
Loosen the pad adjustment discs evenly, one click on one pad, one click on the other until they no longer rub. It may not be perfectly even, one pad may require a bit more loosening than the other. Don't worry about that as long as they don't rub.

Here are the actual owner's manuals for your reference: Avid BB5 and Avid BB7.


Friction occurs in BMX Freewheel I've just found out where friction occurs in my BMX.

When I take chain off the Outer Part and spin the rear wheel the wheel will spin for several minutes but when the Outer Part can't rotate with the rest of the wheel (when chain is on) friction is caused by the Inner Part rubbing against the Outer Part

  Questions

How to find a replacement of the bad part(s) with the least friction? OR fix the friction IF that's a better choice?

What are these parts called?

Yes that is as single speed freewheel and those two pieces should not stick
There are some serviceable freewheels (White) but they are expensive
Pretty sure you need to replace the freewheel
Based on the rust it looks old
If you remove it from the bike and it sticks then for sure you need to replace it
You can try spraying a lubricant in the grove but most likely the bearings are shot

A freewheel is like $30 and it takes a special tool to remove
Take it to a bike shop
If you buy the freewheel from them the often install for free or a small fee

Or check youtube for videos on how to do it yourself
The removal tool for a single speed is like $25 so not worth it unless you are going to do it a few times

And if you are going to replace the freewheel then it is good practice to also replace the chain

As Brian stated this can also happen from a chain to tight.
Chain should have a little play.
And crank the pedal a few revolutions - some times the chain can be more tight in certain positions


I can't sit on my sit bones I'm 195cm and 80kg. For as long as I can remember, I haven't been able to sit on my sit bones comfortably. In hard wooden chairs I slouch or lean far forwards. Plastic seats, such as on a metro, are also quite uncomfortable.

I often struggle with soreness after riding. My skin looks fine down there, but I get a tremendous amount of tissue soreness in the vicinity of each tuberosity. I do wear cycling shorts but not bib-shorts.

It just occurred to me yesterday evening as I was sitting on the metro and realized that yes, my butt hurts if I sit up properly.

Is there any hope for skinny people like me? Is the solution simply ride more? (increase muscle tone, develop awesome butt-calluses?)

I'm curious to hear solutions from other diminutive derriere dudes and dudettes.

Yes, there is hope for skinny people like us.
Please keep in mind that sitting on a saddle for miles/hours on end is never going to be totally comfortable. I'm sure I will get flamed for this but I'll go ahead and state it- there is no such thing as a comfortable saddle. Saddle choice is a matter of mitigating discomfort, not enhancing comfort.
The two most personal choices people make beyond the bike they ride are shoes and saddles. These two items run neck and neck in terms of personal  the preference is. What works for one person may be an instrument of torture for the next and vice versa. Helmets are a not-so-distant third.
What you need to do is try different saddles. Keep trying different saddles until you find one that you deem bearable. Give them time. Someone once told me that "you don't break the saddle in, the saddle breaks you in," and that holds true for pretty much everything with the exception of a certain brand of English fame known for their leather saddles. Unless the saddle is excruciating to sit on for the first short ride, give it a couple weeks of regular riding or a month or so of sporadic riding before you conclude that it's not right for you.
This process can be expensive.
Road saddles are much more difficult than mountain bike saddles because you spend more time on them and move around on them less frequently. I've been riding regularly for many years now. I still haven't found a road saddle that I'm happy with. I have the same mountain bike saddle on every other bike I own except my road bike.

The longer your ride and the harder your ride, the more uncomfortable you will become regardless of your saddle choice.
More padding does not equal more comfort. Do not forget that. That goes not only for saddles but for shorts as well- and everything else involved in a contact point with your body for that matter. Just because something costs more does not mean that it will be more comfortable- same rules apply here as well.
Don't underestimate the value of a good pair of shorts. You probably shouldn't pay less than $60 for a pair and you should do your homework on what makes/models rate well and which dont. There is some personal preference involved with shorts but it's not to the same degree as with saddles. Typically if they rate high you will be happy with them. If they don't you might be better off sticking cardboard down your shorts (I've owned a pair of shorts like this that weren't that cheap). Bad shorts can make a good saddle feel more uncomfortable to a degree, but the best pair of shorts cannot make a saddle that does not fit you comfortable.
To close, I will reiterate that saddles are not very comfortable to begin with. What you're trying to do is find one that limits how uncomfortable you become as your ride progresses. Try enough different ones and eventually you will find one that works. Best of luck.


Reflective tape instead of rear reflector, in Australia I currently have not enough room on my seat post for a saddle bag, rear reflector and a rear light.

My question is if replacing the rear reflector with reflective tape on the saddle bag would be enough to satisfy the law here? The law states: "a red reflector that is clearly visible for at least 50 m from the rear of the bicycle when a vehicle's headlights on low beam shine on it".

Note: My current rear light is a Lezyne Micro Drive Rear which doesn't act as a reflector.

OK, so:

I called Queensland Transport, who put me through to main roads
I then called main roads back (since the first call got disconnected). They told me to call my local main roads office, as their central number doesn't answer questions about compliance.
I called the local main roads office. The inspector there told me this was an issue of legislation under the traffic act, and hence I had to call the Police instead.
I called the police central number; they told me I needed to call the local Police Traffic Branch.

Finally, I spoke to a very nice lad at the traffic branch, and asked him about this question.

He said that the only time you need the reflector is at night, and as such, if you instead have a front and rear taillight, and they're both turned on, then you're compliant. You will not be "pulled over" for not having a reflector on during the daytime when you are perfectly visible.

His thoughts on the tape were that it sounded good - anything that makes you more visible is a bonus - but it wouldn't be any "more compliant" than the light itself.


Can racks cause damage to a bike? Reading this question about the best way to lift a bike on to a pictured rack, it struck me that I'd be less worried about how to lift the bike than the potential for damage by hanging the bike from its front wheel's rim.

Many racks involve putting the rim into a trough or groove, or something like this attached to a wall:

Surely the danger from being struck from the side and bending the rim is quite large? For this reason I try to avoid any rack that I have to put my bike in rather than against or on.

While the concensus seems to be that public rack owners might not be liable for theft, might they be liable for contributory negligence if a bike is damaged directly as a design flaw in the rack?

I am not a lawyer, but it looks to me that it would be a big no. It is your decision to put it in the rack.

And in any case, they are actually pretty good - they are the most common type and I have never had one cause any damage in 35 years.


Safe child seat attachment I was told by my bike shop that the bike I have can only mount a child seat at the seatpost. My son is 2 and I need a safe child seat for him. I have been having great difficulty finding one that mounts at the seat post online and I am reading that its not the safest if not mounted on the back as well. Any suggestions?

The conclusions you've drawn from your research are correct. There are racks that are specifically rated for child seats, and they attach to the bike's frame into a pair of rack stays near the seatpost as well as near the rear axle. Any rack rated for touring or hauling heavy loads reliably will use these attachment points at minimum.

A child seat should be mounted on a rack that attaches firmly to the frame of the bike - which usually includes the seat stays near the seatpost. There are racks that attach onto the seatpost themselves, but these are lightweight racks, generally meant for bikes that need a rack only occasionally, or for road bikes without rack braze-ons; such "seatpost racks" are designed for easy removal and attachment, and are not designed to hold more than the weight of a daypack. Mounting a child seat on one of these would be horribly dangerous.

I sincerely hope that you've misunderstood your shop. Attaching a child seat to a seatpost rack would probably break the rack and then harm the child. I suggest avoiding any shop that gave this advice.

But I find it difficult to imagine that even a marginally competent LBS employee would recommend this. Is it possible that what the shop said was to get a rack that attached to the frame near the seatpost, as well as near the rear axle?

Does your bike have attachment points in these locations? from your question, I'm guessing it doesn't, and I'd seriously reconsider and use a trailer instead of a child seat with your bike.


Any alternative use for old mountain bike tyres and inner tube? I have recently changed the original tyres and inner tube of my 15 year old Specialized Rockhopper. They were starting to deteriorate and I got punctures almost every time I took it on gravel paths.

Before I take them to the local recycle centre, I just wondered if there were any alternative domestic uses for these old tyres and the inner tube? Can they double as something else for gardening or domestic uses? Can they be fashioned into fiendishly simple kids toys?

Tubes are extremely flammable.
I carry a tiny pouch of cut in stripes rubber when backpacking, if things get ugly and I need to light a fire in damp/wet conditions.
Seriously - they burn like gunpowder.
Edit: Reality Check.
Yesterday morning I wanted to start a fire after a light rain. I picked up dry tree branches (from trees, not the ground). Then put about 5cm of tube cut into thin stripes underneath. Touched them with a lighter and was cooking breakfast right away.


Measuring BCD & choosing right chainset I bought a used bike whose chain keeps slipping, and I believe it is because either the chainring or the bottom bracket is bent. I tried to show this as best as I could in the below pictures.

I am looking to replace the chainring, but I can't for the life of me figure out what its real BCD is. It's a 5 bolt, and the adjacent bolt distance seems to be ~91mm, with a measured BCD of ~166mm. The below pictures show the taking of these measurements with a tape.

If I calculate the BCD from the adjacent bolt distance, it comes out very differently from what I am measuring it directly with the tape, and, even if it didn't, either of the numbers seem way off from whatever chainset BCD sizes I am able to find out there - unless this one is a very uncommon one? I mention that the bike is a 20 inch foldable Ecosmo mountain bike, 6 gear shimano. I haven't been able to find manufacturer info on it, but the chainring does have "9902-222-118-52T" inscribed on it, and the brand seems to be "Powerwheel". It has 52 teeth.
What am I doing wrong when measuring the BCD, and what chainring replacement sizes would be suitable for this bike?

It looks like you have a crankset with non-removable chainrings. The 'bolts' you are measuring the geometry of are just screws holding the chainguard on. The chainrings appear to be pressed steel and attached at the crank axle.
It's much more likely the pressed steel rings are bent than the bottom bracket axle, so replacing the entire crank is possibly all you need to do. The bottom bracket bearings may also be in bad shape which would require that to be replaced also.
Single chainring cranks for a square taper bottom bracket are relatively cheap, but there different model cranks require a different axle length to achieve the correct chainline. Sometimes it's easier to buy a new crank and matching bottom bracket than mess with trying to figure out what axle length a crank needs.


How do you know when you need to add more air in the tires? How much air is too little and you should add more for the safety and ease of your bike ride?

Look on the sidewalls of your tires, and you should see a recommended pressure range. If your tires are outside that range, you need more air. The lower end of the pressure range is good for soft ground like dirt or gravel or snow, where you need more traction; the higher end is best for roads, and will help you avoid pinch flats.


What air attachment screws onto a Presta valve with the core removed? High volume for seating bead? I have presta valves on two of my bikes.  I have a presta floor pump.  I have an air compressor.  I have a schrader adapter.  I have a blowgun and a tire inflator for my compressor.  I can attach the blowgun and the tire inflator to the presta valve using the schrader adapter.

What I want to know is what kind of attachment do I need to screw my air compressor on to the presta valve after the core is removed?  The schrader adapter screws onto the valve core, so without the valve core, none of my attachments fit.  What do I need?

This post indicates that people remove the valve core to get a high volume of air into the tire (which I want to do to seat my tubeless bead), but nowhere can I find exactly how to attach my air to the valve without the core installed.

The only things I can find in videos that actually claim to do this are the Park Tool INF-2 Inflator and the Silca Hiro Locking Chuck, which exceed $150 CAD ($115 USD) and $90 CAD ($65 USD), respectively.

Please help, I've wasted hours trying to get a solid answer to this question.

Inflator heads with Presta fittings let you do this because they tend to (always?) seal down around the stem, not the core. I don't know any other way. I suppose you could also take a spare Presta core from a dead tube, break the plunger out of it to get more airflow, then temporarily install it in your tubeless valves and put your adapter on that. This is conjecture.

If you haven't already, one thing you might try if seating the beads with your inflator head plus an adapter just isn't working is first install the tire with a tube, seat the bead that way, then break just one of the beads free and try to do the tubeless seating. This can make obstinate ones go pretty smooth.


Quick-release chain tug? Note: this question is about a QR chain tug, not a chain tug for a QR skewer. Just so we're clear.

My Google-fu must be weak after too much indulgence over the holidays, or maybe it just plain don't exist. I'm looking for a chain tug for horizontal rear fork ends to replace the threaded tug bolt that is currently built into the frame.

Why?
A. I like having the bolt/tug to help precisely tune the chain tension, rather than the "wheel walking" technique we all know about.
B. I'm considering running two sets of rubber this winter and anticipate doing a lot of swap-outs before my daily commute.
C. It adds precious seconds (lol) to my tire change routine and I can't find anything else I want to tweak on my current whip, so I'm micro-tuning now to feed the addiction.

Motivation (from one of my comments):

  The objective of this theoretical QR chain tug would be to allow you
  to "set" the proper tension using the wingnut, but then be able to
  completely release the entire mechanism to be able to derail the chain
  and then remove the wheel. When you reassemble everything, just
  tighten the QR lever and you should be back to the correct tension, so
  then you tighten your axle bolts and you're off to the races...

Anyone know of / invented / hacked such a device?

Feel free to slag me and say, "just shut up and ride".

I can see your idea, though I'm not sure a quick release style chaintug would work. Although I think I can see how it could be made possible. Hopefully I've explained it well enough!
With a standard 'nutted' chaintug (A), distance 'x' is infinitely adjustable as the the brace ('1') moves fore/aft along the threaded rod ('2'), distance 'y'.
With a 'QR' chaintug (B), distance 'x' when tensioned is fixed. The only slight movement here would be when the QR lever is in the open position. For it to work, I guess '2' would have to be threaded through the centre of the QR lever '3'. In doing so, the lever itself would need a cut-out for the threaded rod to pass through when you open up the lever.
So I guess in theory this, or something similar, should be feasible. Whether or not it would be worth the effort I don't know! I use the same tyres (Panaracer RiBMo's) all year on my fixie without chaintugs so I don't have to worry about changing wheels/tyres etc!
Anyway, what's your thoughts guys!?
EDIT
If you just want to be sure you've accurately aligned your rear wheel in the drop out, then an increment etching along the dropouts would be easier.

Turns out someone else already done this..bugger!


Chain drop under load I have a problem. Today I was riding (flat-out) up hill, and went to shift up a gear on the rear, which caused the chain to drop off the front chain-ring (was in the big-ring, so dropped to the outside). (For reference, road bike with Shimano 105, 52/39 and 25/12)

Throughout the ride it dropped a few more times - generally under some form of load. I noticed that it wasn't always dropping off the big chain ring. Occasionally when taking off from lights (in the little ring), when I stood up to get going, the chain would fall off the front chain ring, to the inside.

Is it possible this is anything other than incorrect limit screws? Maybe something out of:

Chain problem (stiff link? But looks OK)
Chain-ring worn (this is on a ~4 year old road bike, maybe 25,000km without chaning front chain rings, but they don't have the 'shark-tooth' pattern)
Bent hanger?

Edit: Here is a look at the chainring

Edit: @Qwirk: If you look at your photo, where the chain is resting on the small chain ring, do you see the gaps between chain and teeth? that is a key indicator of either extensive chain wear, extensive chain ring wear, or both. In this case, based on the appearance of the upper chain ring, I'm going to say both.

Those are the first 3 options I'd look at, as well.

Have you replaced your chain recently? If so, the new chain may not be meshing well with the old chain rings.

To figure out which, first check the chain for wear.

If it doesn't show any serious chain wear, compare the chain rings on your bike to a set of new chain rings. It doesn't have to be shark toothed to e worn, but that is most common. Hooking, or simply teeth that are significantly shortened will cause similar issues.

Check as well for bent or missing teeth in the chain rings. This shouldn't be the case because it's happening in more than one gear, but it could still be. Also, check the rear cassette for missing or bent teeth, for the same reason.

Last, if the rings do not appear worn, you should replace the chain, (or soak it and re-lube it at a minimum). This will eliminate the possibility of a burr or a sticking point in the chain that is more subtle than a stiff link.

Oh, and a bent hanger would have to be pretty visible to cause this kind of activity, but it's still worth checking.

Hope that helps.


Using two tires on one wheel to prevent punctures? I have 20 x 3.0"tires, which seem to be pretty hard to find--especially with nice puncture-resistance like Schwalbe's "Smart Guard," or something of that nature.  Unfortunately, I'm definitely getting more flats.
My mechanic told me that I could double up on the tires--put old tires underneath the new ones so that it forms essentially an inner tire liner.  He did this in the good old days, apparently.  He in fact recommended that over other commercial products (Tire Liners) because apparently Tire Liners cause flats in themselves.
I have an e-bike, so I wouldn't mind the extra weight and might give it a try, but was wondering if anyone still does this today and if there's anything I should be wary of when / if I try it out?

I'd just buy tyre liners (example from Zefal).  They're made from tough polyurethane which many sharp things won't get through or at least not quickly. I've used cheap (unbranded eBay) ones on a cheap bike when I didn't want to buy expensive new tyres, and they worked well, with one issue, probably what your mechanic was thinking of that was easily solved by taping over the end.  They can be cut down to fit your small wheel, and it looks like the ones I've linked are made wide enough. Another popular brand is Mr Tuffy, though I've never used them.

If you want to try recycling instead of buying, then use the tyre liners as inspiration.  Here's Zefal's video on fitting them, so you can see the approximate proportions.


Changing the cassette: is it necessary to change the rear derailleur and/or chain? I recently moved to a city with a lot of steep hills so I'm looking to change my 11-28 cassette to this Shimano Tourney 14-34. I have a Shimano Tourney rear derailleur with the same number of gears (7).

Since the biggest gear (34) in the new cassette is a lot bigger than the one I currently have (a 28 teeth) I was wondering if I could still use my old derailleur.

OK, from my research, and the other answers, this are the steps you have to take to change your cassette:

Determine if you have a freewheel or a cassette? This is a distinction that I initially ignored. It is important because you need different tools to remove and install these, so be careful.
Find your derailleur model, it is usually engraved in the back of it (mine is a Shimano Tourney RD-A070) and google the maximum sprocket that it supports. For my derailleur, it was a 28 teeth gear, but I managed to make it work with a 34t. As always, manufacturer specifications are a little conservative.
Adjust the b-screw in your rear derailleur: here is a How-to tutorial

            . Doing this you'll be able to adjust it for a bigger sprocket.
Using the model of your derailleur, google its capacity. The capacity is the difference in teeth from the gear in which the chain is loosest (the smaller chainring and the smaller rear sprocket) to that in which it is tightest (the biggest chainring and the biggest rear sprocket).

If the capacity of your rear derailleur is lower than your actual capacity, I think you can solve this problem by avoiding ever cross-chaining.

This is what I have been able to come up from zero knowledge about this, so, please, correct me if I am wrong in any of the above.


Rear derailleur doesn't go to smallest cog I'm sure it is a simple fix to this, but please bear with me.
I have recently swapped my rear wheel on my bike (with an identical one, keeping the same cassette). Upon putting it back in, I noticed gears were not changing properly (chain was skipping or it wasn't moving smoothly to the next cog when changing gears).
I played a bit with the barrel adjuster, but before I managed to fix the problem I noticed that a. I could rotate the barrel adjuster infinitely in both directions and nothing was really "moving" and b. the chain wasn't going on the smallest cog anymore, no matter on which chain ring I was.
My questions would be:

Is it normal that gears need adjustments if I change a wheel with another identical one?
How can I fix the rear derailleur so that the chain gets on the smallest cog, and also fix the original problem of non-smooth gear changing?

Also, the barrel adjuster seems to be formed out of two components, each of them rotating independently (with the larger one moving vertically as well, with the help of a spring). Would appreciate some detailing of how this actually works. I have attached a few pictures.
I am talking about an Ultegra R8000 SS rear derailleur.

The inside of the barrel adjuster should screw into- and out of the derailleur  when you turn it. The part around it should only slide lengthwise but should turn with it (there is a slot which allows it to slide lengthwise but ensures they turn with each other).
In my experience the Ultegra R8000 barrel adjuster has an unusually fine thread and needs quite a few turns to move a real distance.
If your second rear wheel is really identical to the first one (same hub, same cassette, same spacers on the cassette (if any) etc.) then it shouldn’t require derailleur adjustments. But I guess different torque on the cassette lockring or some other minor difference could be a reason.


Single speed dirt jump specific frame for general riding I am in the market for a new bike and come from a background of mainly cross country (XC) / all mountain (AM) type riding but have ridden BMX also in the past. I'm not averse to standing up and only having one gear, being quite an aggressive rider I am quite open to the idea of 'less to go wrong the better'.

The area where I live offers varied terrain including; canal paths, nature reserves, dedicated blue route mtb trails and a bmx track. My last ride was a full suspension AM specific build but it was overkill for the area and I am looking at getting into more street/dirt jump/pump track related riding but still ride the occasional XC / AM ride (2 - 3 hours) to mix things up.

My question is;

Would a single speed dirt jump specific frame offer me the flexibility to cover XC / AM occasionally but still allow me to ride from A to B and do some park / dirt riding, or would I be better suited at looking at a 'hardcore hardtail'?

My short answer is no.  A true dirt jump frame is going to be horrible for short XC riding and even worse for extended 2 to 3 hour rides.  You won't be able to get the extension to pedal efficiently and will just end up wearing yourself out standing.  I have a dirt jump frame and after only a couple short commutes on it (4 miles) I decided it wasn't worth commuting on it.  A "hardcore hardtail" looks to be closer to what you should probably look at.  It should be far more comfortable for extended riding, but still handle the abuse of a dirt track.


BMX gearing - for road / commuting I have a 2010 Haro Pro Race, which I bought for commuting and general tomfoolery.

I commute on it 2 miles a day, and I want to be able to go faster by changing the current single-speed gearing ratio.

It currently has no modifications from the standard gearing:

Crankset: 3-pc Alloy 175mm, Euro Sealed Bearing BB
Gearing: 39/14

I find that I can go quite fast with this gearing ratio, but when it comes to going down hill it is just too easy and I no longer get any drive.

Can someone suggest a better gear ratio / crankset that is more aimed for top speed, rather than acceleration, yet still allow me to accelerate from a standstill quite quickly?

what spacing is the is the rear hub? I bought an s2c recently to commute on my track bike, two speed internal geared hub with a gain of 38% but it might be over kill for yourself.

Given your setup you have a gearing of about 55inches, if you were to switch out the rear cog to a 12 tooth you would gain 5inches, bring you to around 60 which is considered a fairly spinny ratio on a track bike.

Easiest way is to switch is the back free wheel. However it seems the lowest freewheel available is 13 tooth so you are limited. You could get a new chainring up front which would achieve the same but may need to buy a new chain too.


Non-quick release through axle - a few questions I just bought an RSD Sherrif II fat bike and it has a carbon fork with a thru-axle. It appears to be a non-quick release axle - no lever of any kind, so I need an allen key to remove it.

I have a few questions:

From some quick reading about removing/installing thru axle wheels, literally all the guides I see are describing quick release variants of the thru axle. Does it mean anything that mine is not quick release? Does that indicate poor quality/ cheapness? Or is it just that fat bike axels are rarer due to their width and not many quick release variants exist?
If I remove and install it with a normal allen key, how concerned do I need to be about the torque rating (80-120 in lbs)? Can I just put it in to finger tight plus a half turn or something like that? Or should I buy a torque wrench for this? I don't want my wheel popping off (too loose), but I also don't want to crush my carbon fork (too tight). Maybe there's a metal internal sleeve to prevent the latter. I just removed it and checked the tightness before doing so, and I would call it on the tighter end of what you could do with a standard allen key.
Can I replace this with a quick release axle? If so, what are the measurements that matter in picking a replacement? The specs for this bike say 150mm fork spacing, but the axle itself has three numbers: L=198mm, TL=9mm, TP=M15x1.5.

Here is the axle mounted in the fork:

It's a Maxle Stealth. They are a little cheaper and are also a weight savings thing. They're not super common but there's nothing wrong with them. They've also not been around very long, just less than two years as of now.

As I understand it, on the Rockshox forks that Maxles are more typically found on, the Maxle Stealth versions are fully cross-compatible in all cases with the quick-release Maxle Lites and Maxle Ultimates that share the same dimensions. So for example, the axle you have mainly exists in the world to be retrofitted unto RS Bluto forks with the Maxle Lite that has all the same dimensions. So it's probably physically compatible, but you should probably double check with the manufacturer before doing it that there are no hidden gotchas.

(Edit: One such gotcha could have to do with any pronounced recesses or grooves on the fork that the shoulder of the Maxle Stealth sinks into that a lever might interfere with. Just hypothesizing.)

For the torque, it's really a pretty wide range they give you, so I wouldn't worry about it too much. On the tight but not strenuous or aggressive end of what you could do with a standard allen wrench is a good way to think about it.


Can single-sided Power meters cause unnatural Bilateral asymmetric pedaling? In case it is not clear for everyone, let me briefly explain the graph. The pink line represents the Power output along the y axis while the grey dots represent Left/Right balance in Power. The x axis represents time.

I was aiming for 360 watts in the beginning. Assuming I had a single-sided Power Meter (for my right leg) it would have showed smaller numbers where the Power Balance was more towards my left leg.

The direct consequence in holding a specific amount of watts using a single-sided Power Meter would be that as the Power Balance shifts away from the leg with the Power Meter, the total actual Power will go up while the numbers remain the same. As the Power Balance shifts towards the right leg total Power goes down.

The indirect consequence is the mind would subconsciously (or even consciously) learn to use the right leg more than the left leg. Especially in those crucial moments, like the last 15 seconds of an interval.

I'm looking for evidence to backup my claim. And since I am 100% certain that I am correct, why do people use single-sided Power Meters? Why do they exist at all?

I am unaware of any controlled study that directly addresses your question.

However, a recently published study by Bini et al. addressed the converse of your question: can the provision of information on bilateral symmetry or asymmetry be used by riders to alter their pedaling dynamics? The Bini et al. study did not address whether riders would benefit from decreased bilateral asymmetry -- it only addressed the limited question of whether it was changeable. The answer appears to be that it can, sometimes. So although your exact question was not addressed, if these results are replicated and verified then a reasonable implication is that if one were to supply the riders with incorrect or misleading information on symmetry the riders might also be able to adjust their pedaling.


Is it normal for a presta valve to unscrew into two pieces? I have a Continental Road inner tube with a threaded presta valve. I also have a threaded bike pump which I screw onto the valve to inflate the tube.

When I try to unscrew the pump, the uppermost part of the valve unscrews and detaches from the main body of the valve and all the air rushes out.

Is it normal for a presta valve to be separable into two parts like this? How can I prevent this from happening?

The correct answer is yes and no. There are in fact two types of Presta valves: One where the core can be removed. Those are often used with tubular tyres so that the inner tube can be filled with a sealant (latex) fluid. Some higher quality tubes also have removable core valves for the same purpose. Normal and cheaper tubes have Presta valves where the core cannot be removed.

There is a special tool to be used for handling the core although like @Michael said the (careful) use of pliers also works.

Another reason for a removable core is the possibility to use valve extensions with high rims.


For fitness's sake, is it better to ride with low cadence in high gear or higher cadence in medium gear? I've started riding to get fit and lose weight. As part of that, I set little challenges for myself, eg: "I'm going to ride these next two blocks as quickly as possible in the highest gear". I'd be pedaling slowly and strenuously but moving quickly. As I got more fit I would spend by far the greater part of my 20klm daily ride in the highest gear.

However, someone at the bike shop where I get repairs mentioned I was doing it wrong - that I should be aiming for higher cadence and only use the top gears when going down hill.

What's better solely for losing weight?

In terms of losing weight immediately, the obvious answer is to use whatever gear combo allows you to produce the greatest energy output.  For most people this will likely be a hair lower than the "preferred" range of about 70-90 RPM -- maybe 50-60, and pedaling as hard as you can.

However, if you want to KEEP losing weight by getting on the bike again tomorrow (or even just later this afternoon) then you should avoid muscle and joint injury by running at a higher RPM (70-90) and not being quite so extreme in terms of putting out effort.

And one should consider doing "intervals" of alternating high effort and low effort (eg, 5 minutes high, 10 lower), as studies have shown that this produces both better weight loss and better muscle building.


What model is this Bottecchia bike? I'm trying to find a decent racing bike for my next triathlon (on the cheap). I saw this bike on Craigslist with no information about the model or features. Can anyone help me figure out what bike this is and how much it is worth?

Bottecchia are an Italian brand who sell everything from BMX bikes to professional racing bikes. Here in the US the brand is probably best known for being ridden by Greg LeMond in his historic 1989 Tour de France win.

It's hard to say the exact model of this bike. It's a low end model from the 1970s "bike boom". The crankset appears to be a Nervar cottered steel unit. The shifters and derailleurs look like low end Huret models. Both are typical of early 70s bikes.

Depending on your budget you could almost certainly do better than this. Bikes have made tremendous gains since the late 80s. Not only have they gotten lighter but they've also become more reliable. I would look for something more recent.


Threadlocker and Bottom Brackets The main threadlocker brand available in the US describes its red compound as "permanent" and requiring heat (> 550°F)  to free up, and its blue compound as medium strength and requiring only hand tools to free up.

I am seeing a lot of photos of bottom brackets with what seems to be factory-applied red threadlocker.  Are manufacturers actually recommending the "permanent/heat needed" variety of threadlocker compound for BBs?

No, it's because the colors are not a universal indicator of what grade/type a particular compound is across brands. Loctite/Henkel products do use their color scheme to communicate strength level, but even there it's more complicated than that because there are different compounds that are the same color and might differ in other attributes like gap tolerance, cure time, need for use with a primer, oil tolerance, etc. People love oversimplifying this point when they talk about threadlockers, but the fact of the matter is there's a whole lot of different compounds out there with very different properties.

The type of pre-applied threadlocker some bottom brackets come with seems to usually or always be somewhere in the medium strength category regardless of what color it is. You'll find examples in blue, green, red, and white, but in practice in this application they all do more or less the same thing, and they don't in and of themselves create situations where extraordinary measures have to be taken to remove the BB later.

A BB manufacturer might have more to say about this, but personally I've always perceived those partial bands of pre-applied threadlocker on cartridge BBs as being primarily an "at least they'll definitely have something" notion, i.e. a bit of corrosion and loosening insurance for the person or factory that's going to put things together dry no matter what, as opposed to ever being the only thread treatment I need. I always use grease or anti-seize on the entire internal surface of every BB shell (or a full coating of medium-strength threadlocker in the case of the right-threaded drive side standards, Italian and French, plus in special cases like Phil Wood BBs). On a certain level this seems wrong or backwards because the dogma is that threadlocker and grease aren't supposed to be on the same threads at the same time, and yet manufacturers who put threadlockers on their cartridge BBs tend to have it in the instructions to grease the threads.

Permanent/very strong threadlocker or retaining compound on BB threads would be a mistake. Medium strength is enough to add a ton of resistance because BB threads are so fine. Phil Wood bottom brackets more or less rely on the cups being loctited to function and still a medium strength (Loctite 242, one of the really common blue ones) is all that's recommended. In this case you're painting the threads fully with liquid threadlocker, which is then capable of providing protection against corrosion with about the same efficacy as grease or anti seize.


How to install a Hollowtech II crankset if it does not fit the top hat? In threaded 2-part bottom brackets there is a plastic top hat/bearing insert/dust cover that goes between the BB's bearing and the spindle, so that they fit tightly and the spindle does not wobble.

The problem is my crankset somehow does not fit the left
top hat: it was pushed out from the BB's left half and split by the spindle.

How is it supposed to be installed and not break if it's too tight?

I have a Rotor BB1 BSA "Designed to work with ROTOR and Shimano 24mm cranksets" and a Shimano Tiagra crankset.

update: It is also possible that you did not need the spacer/cap in the first space. You state you have a Rotor BB. Didn't you try to use a cap that allows using thinner cranks? For example allows an GPX crank with a Hollowtech II BB. In that case the cap would just be something in the way when using a Hollowtech II crank and so no wonder it would be forcibly and destructively pushed out. The link in the text below show another possibility. A cap that allows Hollowtech II cranks in a wider BB.

Maybe you just must be more careful when installing the crank. I cannot think of any special trick that would have to be done to avoid damaging the caps. If there is any significant resistance, stop and try to fit the crank better. At the and one may need a few hits by a mallet, but that us usually when it already sticks out, just not fully.

I originally thought it was part of the sleeve present in Shimano bottom brackets because the question said "Hollowtech II".

These parts of a Hollowtech II bottom bracket are integral parts of the BB. They connect the opposite bearing cups and separate the bearing from the spindle. You fix them when you screw the left side bearing cup. Then when inserting the crank there should not be any potential to damage it if it was installed correctly. The spindle should go inside reasonably smoothly.

One option for an incorrect install might be using the incorrect spacer in between. E.g. using a 73 mm spacer for a 68 mm bb shell and then screwing  the left cup (the force it generates is big). It would then bulge and partially block the way for the spindle. The final damage would be done when forcefully inserting the crank.

Make sure using the correct spacers for your bottom bracket shell on your frame as shown in Difference between Road/Mountain Hollowtech II Bottom Brackets?

There are some spare pieces sold, but not widely available. For example https://www.chainreactioncycles.com/shimano-hollowtech-ii-central-sleeve/rp-prod7428 (this piece is the big one between the cups) and https://www.kineticbikebearings.com/kbbb9037.html (thanks to Swifty for the name). There is usually no need for them so they are not so common in the e-shops. The links are only illustrational. I do not know about your local bike shop, but it is worth asking. You may need a whole new BB.


Burley push button wheels and axle? I'm looking into building my own trailer and I want something similar to Burley's push button wheel system.

My question is, where do I obtain similar wheels/axles?

Here is the Travoy, one of their trailers that uses such a wheel:
https://www.amazon.com/Burley-Design-Travoy-Commuter-Trailer/dp/B0038LPO5Y

Replacement ones sold by Burley are pricey, anyone else have any luck looking for a similar product?
https://www.bikeparts.com/BPC417920/burley-replacement-wheel-16%22-alloy-push-button-axle

If what you really want is Burley hub/attachment guts, just ask around for someone getting rid of a Burley trailer with rotted out or missing fabric. They've sold a lot of trailers and many of them sadly get put outside to languish before eventually getting thrown away once they get nasty.

Alternatively, Ali Express has a lot of the approximate kind of stuff you're looking for. I don't know if you know the term "stub axle," but that is broadly what you're talking about, an wheel axle like a car or a wheelchair where the support is only on side.


Which waterproof shoes? I am looking for waterproof shoes to use on my daily bike commute for home-office moves. I previously had rain boots, and was happy with them. Nevertheless they quickly started to "break" in the middle of the sole because my feet move when cycling.

What kind of shoes are you using for this purpose, which ones would you recommend?

Note that I don't have clipless pedals.

According to French wikipedia, automatic pedals seem to be clipless pedals.

A wide range of manufacturers make waterproof shoe covers (also known as overshoes or booties), for use with both clipless pedal systems as well as your usual set of sneakers (be sure to check out the particular model to see if they're compatible. One designed solely for clipless pedals may be too small for your regular shoes unless you just wear Chucks. Ones which can be used for regular shoes are often marked to work with mountain bike shoes and leisure shoes). They just go over your shoes, and look something like this (not endorsing this particular model necessarily):

But a lot of people commute with their galoshes on regular old platform pedals for a very long time, so maybe you just need a better pair of galoshes?

A big part of not getting your feet soaked is avoiding water getting to them in the first place, which you typically do by using fenders.

Full fenders with mud guards - a lot of water gets kicked up by your wheels, and this prevents a lot of it getting to your feet in the first place. They also help dirt from the road not get into your drivetrain in the first place which is a nice touch.

If you're commuting on a race bike or full suspension mountain bike something, you may not have the brake clearance or mounting points to run something like these fenders (they're some set made by Planet Bike, but a lot of manufacturers make similar ones). In this case, you can get something that mounts solely on the down tube on and on the seatpost:

which will go a long way to keeping you dry (but not as much as full fenders).


Gears slipping after a chain change I have a Lappierre Zesty 314  (2012). I'm running XT rear mech, an SLX front mech, my crank is XT, rear cassette is XT and XT chain. I went to the Forest of Dean and after the day was over I snapped my chain! I picked up a SRAM chain for my bike and now when I pedal hard it slips with a big bang. I have new Eastern Havens so my hub is fine. Can you help with any ideas to help me solve this? Shall I get a new rear cassette?

Look up the proper chain for the components. XT is not a size - that is the group level.   You should size the chain for the number of speeds (gears).

Inspect the cassette.  As they wear the teeth get sharper spaces get longer.  Visually compare it to a new cassette even if you are looking at a picture.

If your chain snapped then possible something else is damaged.  Inspect all the drive components.

A cassette typically last 2-3 chains.  If you get a new cassette then change the chain.

A worn chain wears a cassette down faster.
And a worn cassette wears a chain down faster.

A chain is cheaper and easier to change so cheaper to stay with a fresh chain.
There are tools to measure chain stretch.
Replace a stretched chain.

A new chain on a worn cassette will jump - basically both the chain and cassette stretch.


Fitting questions - Effective top tube vs horizontal I'm stuck in understanding size tables of a bike.

For example this size chart:

Am I right in my thoughts?
Effective top tube (ETT) is horizontal value so, it's B1 on the chart.
BS is the length of line parallel to the frame.
But then why BS is less then B1? (if B1 is horizontal, than it's cathetus of the triangle, it should be less then hypotenuse)

Or ETT is not horizontal line, but the line parallel to the frame?

And also, what is A1 on the picture? It looks like the main value (size of those bikes are called by A1 values), but what is the difference with AS value?

If you look at the full resolution it is clear.
BS is center to center (head to seat) along the (sloped) top tube.
Since the seat tube is slanted that is a shorter distance.
Geomemtry C2C

Cathetus and hypotenuse apply to a right (90 degree) triangle.  There is not a 90 degree triangle on the BS.


How much cycling distance is needed to travel every day for good muscular exercise? As a bicycler I used to travel on cycle daily for about half an hour to maintain fitness of my legs and body.
But I want to know how much time and distance is needed for a good exercise.

As individual speeds vary depending on fitness, bike and conditions, most information on this subject discusses intensity and time spend exercising, rather than distance. Most leisure cyclists ride between 10-18mph (16-30kph) on the road, a bit less off-road. As you can see it's a fairly wide range, so time and intensity are better measures.They can also more easily be applied to other sports.

For good health, the WHO recommends:

  Adults aged 18–64 should do at least 150 minutes of moderate-intensity
  aerobic physical activity throughout the week or do at least 75
  minutes of vigorous-intensity aerobic physical activity throughout the
  week.

If you'd like to improve your cycling fitness as well as your health, then British Cycling has a number of beginners training plans, depending on what you would like to achieve.

However, not everyone responds the same way to exercise, so the improvements are not guaranteed.


How to nonverbaly signal a drafting proposition to fellow cyclist? There are situations when words cannot be used, e.g. during heavy wind or when someone is out of breath. Is there an universal hand signal to communicate a proposition of a chain gang behavior to fellow cyclist?

Yes.

There are a number of different ways to initiate a paceline via hand signals, but the most common one I've seen and used is to make a circle with an upwards pointed finger.

Watch Peter Sagan (white jersey, yellow/red helmet) do this in the following video.

He's joking in this situation, but note that his fellow sprinters all know that he's referring to starting a paceline, which is why Greipel (green jersey) checks the gap to the rest of the peloton.


What method or algorithm is used for computing power curve on Strava? Many cycling analytics apps like Strava, TrainingPeaks or GoldenCheetah are offering the critical power curve chart, computed from the power meter data.
I'm familiar with the curve meaning and usage, but I'm curious how the curve is computed from the time series.  I guess it is a more general statistical method, but my search for the literature with method description was not successful so far.

From Strava Support:

  The Power Curve shows your best average power for time periods of 1 second up to the length of your ride. We search your entire ride and find these best efforts and you can compare them with your best efforts for your last 6 weeks, the current year, years in the past, or all-time!

  -- Using your Best Efforts Power Curve (Summit)

As you are already aware, your critical power (CP) is the maximal power you can sustain without fatigue for a very long period of time. CP is also sometimes defined as the maximal power produced over a finite time period (e.g., CP30 would be the maximal power you can sustain for 30 minutes). The Strava power curve  therefore gives a variety of CP values across an array of duration intervals.

In the past might have been done with lab experiments (e.g., you warm up, then do a maximal effort on a bike ergometer or on a power meter equipped bike for a series of set durations), where you would then infer intermediate points based on some type of interpolation or statistical model (e.g., Monod-Scherrer).

With continuous performance tracking (i.e., bike computer + power meter) this can be done empirically  by querying all data within a ride or over a period of time (e.g., last 6 weeks) to determine the maximal power over a set of differing time intervals. These independent queries are then used to build the power curve displayed.

The Strava Power curve, is therefore an empirical curve based on cherry picking your best efforts for a series of durations, dependent on context (i.e., current ride or past effort(s)).

If you never put in a hard effort for a given duration in your ride, or in the past, then the empirical curve will underrepresent (i.e., biased low) your actualized potential if you were to do a real maximal effort. That said, if you didn't put in an maximal effort over a given duration (e.g., a 5 minute interval) you will clearly see it in the power curve associated with the ride, as the curve at the 5 minute mark will be lower than your historical best.

What About Statistical Model Fitting?

Another possible way to generate the curve is to assume that the true power curve of the athlete (what you would like to estimate) follows a particular mathematical form (i.e., parametric) and estimate the parameters associated with that mathematical curve based on your observed values and some sort of objective function (i.e., likelihood).  The problem with this approach is that you have to get the form of the latent curve correct, which can be difficult as people do not have uniform abilities across differing timescales.

For example, some athletes may have very strong short-duration power (e.g., 30 second CP), but lousy long-duration (e.g., CP60, otherwise known as functional power threshold [FTP]). As such correct form of the parametric curve will depend on the athlete, making a generalized fit routine problematic.

There are of course other alternatives that are more flexible with regards to the shape of the curve. Some of these include fitting splines, general additive models, or kernal smoothing. These are all computationally expensive and come with their own set of assumptions and drawbacks.

Given the volume of available data, an empirically based curve is simpler and likely more robust.  You typically start fitting parametric statistical models when you are more data starved and each individual data point is more trustworthy.


Rear wheel causing road bike to vibrate I have a 2019 Giant Contend 3 road bike and I have been having an issue with this bike on and off for the past month. The issue is that when I start pedaling the bike it vibrates. The vibration seems to be coming from the rear wheel. The vibration also makes a squeaking sound, which occurs once each time the rear wheel makes one full rotation. When I speed up the vibration goes away but I still feel some resistance in the rear wheel. Moreover, when I engage the rear break the vibration comes back very strongly.
I went to a bike mechanic when the issue first arose and he told me this was a problem with the bearings in the rear wheel and recommended that I replace the entire rear wheel as he didn't have any spare parts to fix the bearings with due to the coronavirus supply shortage. I went to a different bike shop and they managed to fix the problem. Everything was fine until today when the problem came back.
Does this really sound like a problem with the bearings in the rear wheel? If so, what is wrong with the bearings to produce this vibration and what is the cheapest way to fix this problem permanently?

Yes, a hub that's loose and torn up inside can cause what you're experiencing, and given the evidence you present sounds pretty plausible.
Your experiences with the shops suggest that one or more of your bearing races (cups and/or cones, typically starting with a cone) are damaged. The one that recommended a wheel was cutting to the chase. The one that adjusted it did so because adjusting out the looseness of a damaged cup and cone hub can limp it along, but the nature of cup and cone hubs is that a good adjustment becomes impossible once there's any damage, and the damage perpetuates. So they tightened it, it got more torn up inside, and now it's worse - hence the virtue of cutting to the chase.
If it were just a problem with the cones, they can sometimes be replaced on an OEM wheel such as this. Having a shop do that plus the overhaul labor is often iffy value because the cups, which aren't replaceable, are likely to have picked up some damage at this point too. It's perfectly likely they're heavily damaged, in which case going straight to a new wheel is the only reasonable option.


NOS vintage hub vs modern hub I have an early 80s Schwinn Prelude. I need to replace the rear wheel.
The question at hand is should I spend $300 on a pair of NOS (new old stock) Superbe Pro hubs, which have the original 126 mm spacing it came with, or should I respace the rear dropouts to accommodate a modern spacing (130 mm). I like my current gear ratio as well as the classic downtube shifters. I could be convinced to modernize to bar shifters and 8-10 speed cassette but I'd like to see what my options are.
The fundamental question is as follows: is a vintage high end component set better than a mid range modern set (eg. Tiagra)? Specifically the hubs and bearings?

If period correctness is not an issue, a modern cassette hub is the better choice. The problem with old freewheel design is that it puts the drive side bearings in the center of the axle where the weight of the rider can bend or break the axle. Modern hubs either put the bearings to the end of the axle or use an oversize axle that can take the load. Other benefits of modern hubs are that because the freewheel mechanism is part of the hub, you don't have to pay for new one when the cogs are worn out, cassettes are easy to replace because they don't tighten themselves when riding and finally, there are lots of affordable decent quality cassettes to choose from.


Bike Polish for Carbon Frames I'm looking for a recommendation for a good bike polish for carbon clear coat frames.  Something the fills in minor hair line surface scratches and leaves a nice shine.

Not sure about filling in hairlines, but I have used Pledge and have been very happy with the results!


How do I identify the correct battery for my electric bicycle? I would like to replace my heavy battery to a lighter one. My current battery lasts for 5 days, if I could replace it with something that can only last for a day, I'm fine with that but lighter. Is this possible?

My ebike specs are:
Motor type, 450w brushless
Rated voltage, 48v/20ah

Yes it's possible, but there are a few things to check before getting a new battery:

Some battery systems communicates information to the controller. There are no standards here, so most likely different brands are not compatible.

To know whether your battery has this, check connector between the battery and controller. If it's more than a simple 2 pin (positive and negative) connection to the battery, it's likely you'll need to get a battery from the same brand and ask them about whether it's compatible.

If there's only a simple connection, then you're in luck, as you can use a generic battery as replacement. But there's still a few things to be aware of:

Find a battery of the same voltage (48V) and type (I'm assuming Li-ion based on the voltage and capacity you provided).
If possible, find out the maximum current draw from the controller. Common values range from 15A to 25A. Your new battery should be able to handle the same amount of current to prevent overheating and damaging the battery.
The new battery should have a battery management system (BMS) with protection from over-current. This will ensure your new battery has a better life span.

Side note: because of the smaller capacity, you'll be using a wider charge and discharge range on the battery. For Li-ion batteries, this results in shorter lifespan of the battery. Just something you might want to be aware of.

As a rule of thumb, you should get a battery size that will mean you only need to use max 80% of it's full capacity before recharging. This will greatly enhance the lifespan compared to a 100% charge / discharge each time.


How can one stop brakes from screeching? I'm hearing that annoying sound when you use your brakes and you get the chills from the screeching sound.

I have disk brakes and a relatively new bike.

It happens to be front tire shown below.  I checked for contaminant and none exists.

I would recommend swizzstop discbrake silencer, and sand the surface if the brake pads with fine sandpaper.


How can I run a dynamo wire from my front hub to my dynamo light? I have a Pashley Roadster Sovereign, and wanted to upgrade the dynamo driven headlight. Sadly, I didn't successfully use the old wire to pull the new wire through the front fork, and now I need to fish a wire through the fork without the aid of something to pull it through. Any tips for accomplishing this? When I try to fish the wire down the fork, it catches on something and I've never successfully located the end of the wire through the vent hole.

I was finally able to do this by taping the end of the wire so it extends about 1/2" past the end of a bent-straight coat hanger. Using this, I was able to get the tip of the wire near the bottom vent hole, and wiggle it around enough that I could locate the wire ends. Then it was a bit of work to catch the wire and pull it through with fine needle-nose pliers, but I was able to get it twice within a minute or so after burning nearly an hour trying to fish it through using other methods.


Is it worth buying a RFLKT+ or is the RFLKT good enough? Looking at Amazon, the Wahoo RFLKT is half the price of the Wahoo RFLKT+. What practical benefits would I actually miss out on if I just went with the Wahoo RFLKT? Any pros and cons of the two different models?

I have a RFLKT+ which I use with Cyclemeter. The significant differences are the altimeter and the ANT+ bridge. The reason why I bought it was so that I could use ANT+ sensors, specifically the Garmin magnet less speed and cadence sensors. The altimeter seems to be very sensitive and enables more or less real time grade display – just in case you want to know why you're miserable climbing a hill :-)

If you don't need those features, then I don't think there is a reason to by the plus version.

One other thing that I'd add is that the connection to ANT+ sensors is not as robust as I'd like. I find that I have to pay attention to the sequence in which I wake up the sensors and start the app to ensure that everything works. It seems like the sensor discovery process can take quite a while (maybe as much as a minute) which adds to the aggravation.

I'm not sure if this is a RFLKT+ thing, an ANT+ bridge thing, a Garmin thing, or a Cyclemeter thing… But if the fiddling with hardware and software isn't your thing this would be another reason to lean towards the RFLKT (the Bluetooth link seems much more robust).


How can I know if a crankset is compatible with my bike without physically seeing it? I'm using Shimano Tourney TX right now and would like to upgrade. I can only shop online and can't visit physical bike shops. I'm leaning towards SORA R3000 but I'm not sure if it has the same BB size as Tourney.

In general, you may be able to check the bike manufacturer’s page for your bicycle. They will usually list all the components the bike is built with. However, the list may not be comprehensive, especially if the manufacturer mainly sells lower end brands.
Bottom bracket standards can be confusing, because there are a number of variations. In this case, you could have looked at Shimano’s web pages for the Tourney and Sora groupsets.
The Tourney crank takes a square taper bottom bracket, where there’s a square spindle in the BB. The Sora crank takes a Hollowtech II bottom bracket; here, the spindle is integrated with the crank, not the BB, and the latter is a set of cups with bearings. So, this is a different type of BB.
The term size is ambiguous here. However, your frame most likely has a bottom bracket shell that is designed for threaded BBs, most likely with English threads. In general, in shopping for BBs, you need to consider the frame’s BB shell type, and the crank spindle type.
Do be aware that it is usually not economical to upgrade a lower-end bike piecemeal. Bike manufacturers buy components in bulk from the group set manufacturers, and they get big discounts. It is often more economical to just sell a lower-end bike and get a higher-end one. If the issue is that the chainrings are worn out, then just in case you aren’t aware, you should be able to get single replacement rings. Also, I’m not sure the Sora crankset will be a major upgrade from Tourney. That said, if you are aware of this and you still want to upgrade the crankset alone, you shouldn’t let an Internet forum stop you.


Removing a seat post spacer I am trying to get an old Raleigh SC 40 bike back to riding condition. The seat post doesn't tighten at all and the culprit is that the spacer sleeve is stuck well into the frame.

In order to get a new seat post, I would assume that this spacer needs to be removed.  Any ideas for easy removal.  I tried to wedge a small flat screwdriver between the spacer and the frame but still can't loosen it. Looking at it I would assume that it is aluminum (definitely metal). Use WD 40? Then what!?! Thanks!

It’s much easier to push than it is to pull.

So I suggest you remove your bottom bracket entirely and then push the spacer all the way down into the bottom bracket space where it can be then cut, folded, spindled, and mutilated.

Appropriately sized wooden dowels or PVC tubing would be your best bet if you didn’t want to mar the seat tube. Very long handled minus screwdrivers can be used if you don’t care anymore. An aluminum spacer may have cold welded itself to a steel seat tube and in those cases, chemical or thermal assistance may also be needed.

Ps. I don’t actually see a seat post clamp on your bike in your pictures and so I’m assuming you do actually have one.


Will using dry lube and wet lube together give you better protection/performance than from using just one of them? I think the only way to use them together is to put on dry lube first and then wet lube.
Will the wet lube hold? Will applying both give you the best that each has to offer?

Update
Just found this video on YouTube. It teaches you three techniques to clean your chain. If you forward to timecode 8:20 of the video. He mentions that you can put on Finish Line's Dry Teflon Lube and later you can put another lube on top of it:

Just wondering if this is ok.

Update
Just bought some Finish Line products to do some chain maintenance. On the back of the Finish Line product pamphlet they have a list called "Pro Team Mechanic Tips". Two of the items on the list contain techniques that use two different lubes/greases on the same chain...I've included them below...

In extremely wet conditions, some mechanics will lube the chain with WET lube, then apply a top coating of Teflon Grease to the chain.
In semi-wet conditions, some will apply DRY Lube to the chain as a base coat, and then a top coat of WET lube.

So, I think based on this list and the video link I found above.  Applying both lubes is an acceptable technique.

I don't think so - they are designed to be used individually, and for a specific purpose.

Like I answered to a previous question, the Wet / Dry naming of the product is a hint as to what conditions the product is designed for.

Wet lube is typically more like motor or sewing machine oil, and is designed to coat the chain and protect it in wet conditions. This will pick up dirt and gunk, but it will be mostly kept on the surface and will help keep water and other corrosive substances out of the links.

Dry lube is usually a teflon lube in an evaporating or wax base, so the teflon particles stay in the links without a lot of wet "gunk" left on the chain to pick up sand, dust, grime, etc. and is great for dry, dusty conditions.


Friction-shift (rear) always changing up the gears I have an old french touring bike (from the 70s or 80s) with downtube friction shifters.

I recently had it serviced, and ever since there's been a constant pressure on the rear gears which means they have a propensity to shift into the highest gear. If I shift into a lower gear and let go of the shifter, the chain works it way back up the gears. I can generally maintain being in the second highest gear (which is the one I use most often) but it still requires periodic movement of the shifter as it moves its way forward.

It's possible that before the service the mechanism just wasn't lubricated enough for this to happen.

Does anyone know what's causing it and how I can fix it? I'm afraid I'm pretty much a beginner.

Rode downtube friction shifters bikes for a while.
I can see two possible causes : either the shifter was too lubricated, or the screw isn't tightened enough. Try to tighten it more, but pay attention not to tear the screw.
Usually the lever is pretty rigid when moving. If it's easy to move it to the point it moves alone, it's probably because it wasn't tightened properly.
If this does not work, you'll have to unmount it and delubricate the parts a bit.


Type and strength of a typical chain I'm crafting a small 3 speed "gearbox" for a project of mine and I'm aiming for simplicity in the first place since I'll have to create it myself and I'm not particularly gifted when it comes to using my hands.

Initially the idea was to buy proper cogs but when I discovered how their prices go I resorted to using bicycle sprockets from a cassette like this one which go for ~$10.

Basically I'll take it apart and have 2 shafts with sprockets on both sides matching my calculated gear ratios, one side will be on bearings, all 3 pairs, respectively for my 3 gears, connected with a chain piece of their own and I'll have selectors sliding on the bearing side engaging different gears - pretty close to how a conventional gearbox works just a poor man's version.

My problem is I can't figure out what type of chain goes on a typical mountain bike you would see sold commonly in any casual bike store. There are a bunch of different claims I found which lead me to believe that it's either 25H or T8F but I couldn't determine with enough confidence to order.

The maximum force that will need to be exerted in order to propel my vehicle on the steepest hill I've designed it for is about 650N, which multiplied by wheel size comes out to about 150Nm on the output shaft. That's roughly about 60kg I'm assuming the chain and sprockets will have no problem handling that.

There are several different sizes of chain based on the number of sprockets used in the rear cluster (e.g. 8-speed, 11-speed).  These are 3/32" nominal width.  Single sprockets for these chains are available, but can be hard to find and/or expensive.  In your application you may be able to get away with a slight mismatch, i.e. using a wider chain than your sprockets would suggest (an 8-speed chain on 10-speed sprockets, for example).  This wouldn't be a good idea on an actual bike, and it could get fiddly if you mix and match too much.  Here are the relevant spacings.

The alternative is singlespeed components - they use 1/8" chain and sprockets are always sold singly.

If you're going to pick up cheap used cassettes, I suggest you pick one type and stick to it.  All 8-speeds should work well together, or all 7-speeds, but less so for higher counts.  7- and 8-speed parts are cheap if you want to buy some new, while 5- and 6-speed can be hard to find and 10-speed or higher will get expensive.

As for the strength, consider the forces involved in hard pedalling - let's say a 100kg rider standing on a 175mm crank with the chain on a 22-tooth chainring.


What to check after blowing tire off rim Recently, after mis-reading "35-65 PSI" on a tire sidewall as "35-85 PSI" (in retrospect the unusually huge range should have tipped me off), I inflated a tire rated for 65PSI max to 80PSI. A few minutes later it blew off quite violently, giving me quite the fright.

Now I'm nervous about using the tire again, wondering if it will blow off again more easily now, etc.

So my question is a) would you generally continue to use a tire that has blown off a rim once or is best to chuck it, and b) what aspects of the tire and rim would you inspect and what are you looking for to determine if it's safe to keep using the tire? The one I mentioned looks like the rubber around the bead is a little roughed up but not terrribly so. I'll add a picture when I get home.

Thanks.

I'd change it for a better tire, one that's much tighter on the rim.

You inflated out to only 15 psi over its maximum. That kind of force could easily be generated in a quick turn with the brakes on. If the tire blows off in such a scenario, then you'll be underneath the vehicle you were trying to avoid.

Go to your LBS, and explain that you want a tighter tire. They should know which tires are tighter. Don't let them argue with you, this is about the safety of your life.

(While tires and rims are supposed to be a nominal size, some are slightly larger and some are slightly smaller. Having a large tire on a small rim makes changing tires easier, but at great risk. Hence my advice to find a tighter tire).


Do I require a washer/spacer/shim between a hub's cone nut and lock nut? When replacing the cones for a front hub with new ones, is it okay to tighten the lock nut directly against the cone nut?  Or must I use some kind of spacer / washer / shim in order for some other reason than spacing?

The reason I ask is that I am replacing the cones on a front hub that was correctly spaced at 100mm.  The old setup has

Lock nut - Washer - Cone nut - Hub/Cups - Cone nut - Washer - Lock nut

The replacement cones I got match in the old ones in all ways except that they are slightly wider (i.e. take more space of the axle).  So, instead of getting two more cones ($20 more dollars!), I figured I could just leave out the old washers and leave the setup like this, which would be spaced about 100mm:

Lock nut -      New Cone nut - Hub/Cups - New Cone nut      - Lock nut

So, would this be alright?  Does the original washer play any other role than just making the spacing correct?

I've just rebuilt a totally stock Shimano wheel set and it had locknuts touching cones all over the place. Go for it.


Help Me Identify My Old Norco Bike I bought this bicycle second hand two years ago. The previous owner did not mention the model or year.

I messaged a Norco customer service representative. He couldn't pinpoint the model or year, but said it was probably from the early 90s.

The serial number of the frame is: Y9N3724

The wheels are not original.

Here is a link to an imgur album of more pictures: https://imgur.com/a/cO7NsPi

Not easy with such an old bike, but i've managed to piece together some useful info.

I believe it is a Norco Monterey:
https://freelanderbicycles.com/blogs/news/17350229-the-restoration-of-brians-norco-monterey

https://www.bikeforums.net/classic-vintage/1061887-early-1980s-norco-id-help.html

Further reading suggests that it was likely designed in Canada, but produced by Yamaguchi Sports in Japan.
With that in mind we can use the info in the following link to make a good guess at interpreting the serial number.

https://www.bikeforums.net/classic-vintage/1042901-asian-serial-number-guide.html

So I think your bike was most likely manufactured during weeks 28-29 of 1979


Weed-eater bike conversion - Safe rpm? I've recently started working on retrofitting an old bike with an even older weed-eater engine.  The engine will sit atop a bicycle rack and directly drive the rear wheel tire (engine has a built-in clutch).  I've already constructed the engine mount and obtained other hardware. http://imgur.com/a/we3bn

My concern is that once I get moving (maybe 15-20mph) the chain will be moving so fast around that tiny sprocket that it will come off.

My concern is that once I get moving (maybe 15-20mph) the chain will be moving so fast around that tiny sprocket that it will come off.

You can use a chain tensioner to keep tension on the chain, so some slack on the chain won't cause the chain to skip off the sprocket.


How reliable is the "smart" brake detection on a $20 tail light? Here are some "smart" tail lights I found on Amazon:

Having the same looks, prices, description grammar, no-name random "brand" names and sometimes even stock photos and videos, these seem like each-other's knock-offs coming from the same factory.
While I absolutely love the brake detection idea, should trust these with the technology and execution?
Or is there a bigger brand that introduced this idea that I should go for instead?

The brake detection is based on an accelerometer, and is not a complicated feature.  I have had a similar feature on a Chinese front light and it worked ok from what I can see. So that's probably not a key reason to buy a branded light instead.

Amazon are often parasitical in these products - AliExpress charges $11 for a similar (same?) thing
https://www.aliexpress.com/item/4000239342283.html
Cheap lights, especially tail lights can post a risk of death, in that I have purchased cheap lights from Amazon (albeit originally from China, similar to this), and they went out with no warning (battery dead) on a high-speed road.  (Though apparently some or all of the lights you link to have a battery indicator feature)
The biggest problem with these lights tends to be:

small battery
excessive brightness draining said battery
lack of proper voltage-sensing battery indicator (about to die in 10 seconds is not good enough)

As a second light it would be ok, but I would not rely on it alone.
If you want a better product then a brand might well be better in several ways.
For example:

https://www.cateye.com/intl/products/safety_lights/TL-NW100K/
https://www.cateye.com/intl/products/safety_lights/TL-LD710K/
https://ride.lezyne.com/collections/alert-led-lights
https://buy.garmin.com/en-US/US/p/698001 - This is Garmin's actual radar light which gives you alerts for oncoming vehicles

The best quality light like you mention (and possibly the first) is made by Lupine:
https://www.lupine.de/products/tail-lights
The Rotlicht Max is 1680 mAh battery, the Rotlicht is 830 maAh
The AliX light is 420 mAh, the Cateye Sync is 500mAh and the cheaper model will be even less, and the Strip Drive Pro is 800 mAh.
Exposure are a similar quality brand to Lupine, and they have a 1500 mAh light
https://exposurelights.com/products/bike/rear-lights/blaze-mk3-reakt-peloton
and a 700 mAh light
https://exposurelights.com/products/bike/rear-lights/tracer-mk2-reakt-peloton
The Exposure & Lupine products are clearly much better than the AliX one, but they cost 10x as much, so they should be.
By paying for a brand you might get better build quality, better attachment mechanism, weather sealing , packaging, marketing, larger battery, better documentation, support videos, warranty and so on.
I don't think you could go too far wrong by buying one direct from China and then if it turns out to be inadequate then upgrading to a quality brand later. Or you could just go straight to quality now.


Sram Eagle NX Rear Derailleur not reacting to cable tension Have had a SRAM NX Eagle rear derailleur (bike is a 1x) on my YT Jeffsy for about a year and a half. For about the first year, worked awesome, indexed the gears a few times and all was good. Last half a year its been a disaster.
I can't seem to get it shifting properly in either direction. I replaced the shifter cable AND housing (i know some people will just replace then shifter cable) and still having issues. What i've diagnosed is that it will shift up (or into high gears) and then the derailleur will get "stuck" when trying to shift back down to low gears. I can see the cable going slack and removing tension (i'll shift down ~3 gears) but the rear derailleur won't move from the highest gear. If i lightly move the rear derailleur back and forth it will overcome whatever is causing it to stick and then shift down into the intended 3 gears down all at once. Usually if i get up to 5 gears or so it will start shifting down without me touching it. Any ideas?

If you've replaced the cabling and you see it slackening off with no derailleur response, there must be some added resistance in the movement of the derailleur itself.
I suspect it is simply the pivots of the derailleur which need some lubrication. Either a spray of teflon lube on each pivot point or a drop of oil. Then, if you have the wheel off the ground, you can move the derailleur up and down the cassette while spinning the pedals, to exercise the pivots and free them up. Just mind your fingers.
Double check the guide pulley is far enough away from the cogs, something like 13mm from the largest cog for Eagle, so a decent gap.
I can't think what else would resist the return force of the derailleur spring, except a lack of spring tension... if you handle the mech and it still has finger-crushing spring tension then all good, but check the spring for any defects.


SRAM chain came with only half a powerlock I just bought a new cassette and SRAM 9-speed PC 971 chain. On the outside of the package a power lock is pictured. However, inside the package only one half of the power lock was included. There must have been an error in packaging at the plant.
Can I install this chain by removing one of the end links, and use my chain tool to connect the two ends? I will need to re-use the pin that I had to pop to remove one of the end links. I bought this chain on line from Sports Basement. All those stores are in California and I am in New Hampshire so a quick fix is not possible.
Has anyone ever had something like this happen?

No, don't do that unless it's to limp the bike home. SRAM says not to and I've seen sufficient evidence it's for good reason.
The theoretical/manufacturer-stated reason not to is that the press fit is prone to not being as strong as intended once you've pushed the pin out and back in.
The pattern I've seen when people, myself included, do this is that it can seem to be fine but is in fact prone to breaking. When it happens it's usually during a shift under load, particularly in front. It needs to be in just the wrong spot, so you can see how it can give the illusion that it's fine.
Re-using an old one for a while would be fine, as would be using a 9-speed KMC Missinglink if you can find that locally.


Cycling on Manchester Metrolink tram routes I have been looking around for information on this topic but can't find anything definitive.

The tram routes through Manchester city centre are for trams (obviously), but it seems public transport can use the tramways as well.  My understanding is that is legal for cyclists to use bus lanes, so does the same apply to the tram routes?

I also seen people cycling on the tramways, but are they actually allowed to do so?  Just because people are doing it doesn't make it legal after all, as plenty of people cycle on the pavements as well (which in Manchester is a special kind of stupidity given how busy the streets are!)

Is there any official policy on the status of the tramways as cycle routes?  I do know that Metrolink are rather hostile to cyclists, and I certainly wouldn't want to lose an argument to a tram whilst on a bike...

Highway Code rule 300 - You MUST NOT enter a road, lane or other route reserved for trams. A road or lane reserved for trams will have signs like this:

or road markings that say TRAM ONLY.

If cyclists are allowed on that particular section of tramway then it will be indicated by a sign, like this above or below the tram sign:

or the road markings will indicate that cyclists are allowed (this is from Edinburgh):

Legal issues aside, cycling along a tramway can be dangerous. This blog entry describes the problem:

  The tram lines have also proven to be a nightmare for cyclists – set in smooth concrete or rough setts, with buses and taxis forcing your line and on dark and wet nights, many a cyclist has fallen victim to them and broken their bones and their bikes. It was apparent that the people behind Edinburgh’s tram had made absolutely zero allowance in their thinking around how cyclists might “interact” with tram lines when forced across them at shallow angles by poor road design and by other road users.


How much does nipple choice affect wheel weight/stiffness? Would I be a fool to replace the nipples on a Dura Ace 7900 C24 wheelset with a set of DT Swiss anodised alloy nipples, in the interest of aesthetics? I want the bike to look nice, but don't want to compromise on performance!

Alloy would save a tiny amount of weight. I wouldn't expect it to make any difference to wheel stiffness, so long as you lubricate the threads when building it (alloy nipples are stiffer to turn otherwise, so it's harder to get the tension right). Brass is stronger, but you shouldn't have to rely on that to get a stiff wheel.

But long term, alloy is more likely to seize.

http://sheldonbrown.com/wheelbuild.html#nipples

http://singletrackworld.com/forum/topic/alloy-spoke-nipples-or-brass


Chainring for 1x8 drivetrain I'm building a city/light-touring bike with a single chainring and an 8 speed cassette (11-32T). I bought cranks with the wrong chainring; one for single speed, with a 1/8" chain. I now want to make sure I get the correct chainring. I'm looking for around 44-46 teeth. I'm having some trouble finding one that's not too expensive. I'm looking at this one:

https://specialites-ta.com/plateaux/road/single-chainring.html

It says "Compatible with 7, 8, 9 and 10 speed chains", which I assume is 3/32" chains (what I have), but I'm thinking it might not work well with the lateral movement of the chain from the rear derailleur, as they don't mention derailleurs at all: "Chainring for single use, such as tandem, Rohloff, single speed, urban fittings ...". Can anyone shed some light on this, or what I should look for in a chainring for this use case? Thanks!

If it specifically calls out that it's compatible with 7, 8, 9 and 10-speed chains, I have to assume it would also be compatible with those systems.  That link resolves to a "404 item not found" on my end, don't know if it's a regional thing or what, so I couldn't look at it myself in this case.


Would a Shimano 105 R7000 left side crank fit on an Utegra 6800 crankset? I'm looking at getting a left side crank power meter and was wondering would the various shimano left cranks available with power meters fit with the existing Ultegra 6800 crankset I have? The 105 or even dura ace. Thanks

Yes, you can use the left crank arm of your choice from the Hollowtech II road series. (105, Ultegra, DA)
It is quite commonly done, especially using a newer generation arm on an older chainset where the older style is no longer available.


How to properly gear compensate for short crank arms? Is there a linear relationship between gearing and crank arm length?  For example, on my multispeed bike, my favorite gearing is 34/20 which is 1.7 and with 26" tires, that is 44.2 gear inches but I have 170mm crank arms.  For my wife to be, I want a similar "feel" (pedal effort) but her bike has 24" diameter tires and 140mm crank arms.  So does that mean instead of shooting for 44.2 gear inches, I should also compensate for the shorter crank arms and instead go for (140/170) * 44.2 gear inches = 36.4 gear inches?  If so, since they are 24" tires, I will need about a 1.5 gearing so something like 34/22 or 32/22 sprocket combination should be just about right.

Additional information (although not sure if relevant here) is I am 5' 9" tall and she is 4' 11" tall.  With her shorter, weaker legs, I am thinking a little extra compensation is in order.  The "shortest" gearing I can go with (using sprockets I already have), are 28/22 which is 1.27 which will be 30.5 gear inches.

Being able to easily compare gearing across bikes with different crank lengths is the main reason why Sheldon Brown advocated switching to the proposed Gain Ratios system for expressing bicycle gearing. Gain Ratios measure gearing in terms of movement of the pedal rather than rotation of the chainring. You can use his popular Gearing Calculator to check it out. The other systems are more or less racer-myopic and force you to do additional math when different length cranks are involved, but yes you've got it as far as how to do so.


What are the advantages of having more than one bike? I have decided to keep my Norco Yorkville even though I weigh 265 pounds.
That is well over the manufacturer's limit even without cargo like groceries. I have just upgraded the rear wheel due to the original breaking spokes. Next year the front wheel gets the same treatment.
If I got a fat bike it could be relegated to cargo duty with the added bonus of being able to ride in the snow. I live in Canada and
riding my bike was an adventure today.

What I want to know is if there are other advantages to having two bikes.

Rule 12 says that you should aim to own N+1 bikes, where N is the number you have now.  While that's completely tongue-in-cheek, there's some merit to having gear fit for purpose.

For example I have a fast road bike, which is uncomfortable in the rain and useless for carrying stuff.  I also have a 20" folder with carriers and mudguards/fenders, which is okay for moving things, towing a trailer, and works well in the rain.  But fast it is not.

The advantages of multiple bikes is flexibility

Each can be set up for specific types of riding
You can have a dedicated rain bike without having to add stuff
Spare bike to ride if one is down for some reason
Spare bike to offer to other people if they visit

The disadvantages are

Extra cost - bikes aren't as expensive as cars, but aren't generally free either.
Storage space - you can only ride one at a time, the rest will be stored somewhere.
Upkeep - more bikes means more things to maintain and service, but your mileage is spread over more things.
Records - you will need to keep better records over what was changed when, and how much mileage a bike has done.  I use strava for this.

In your case, the bike might be "over the recommended load" but you're working on that BY riding.

If you find that the bike is not performing to your needs then an additional/replacement bike might help.  This is different from you not performing as expected!

What would a fatbike do for you that your current bike doesn't?  It would likely go slower, weigh more, be harder to climb grades, and tubes/tyres are expensive.  On the plus side it would "float" over sand snow and loose dirt better, but it is not necessarily going to be any stronger or tougher than your existing bike.

You're only 20 kilos heavier than me, and you've already uprated the rear wheel.  I'd suggest riding it while you work on your fitness, and plan on a replacement bike in a couple years.


Any experience with spokes breaking on new Trek 720 touring bike I have a new Trek 720 Touring bike with about 1000 miles and have broken two spokes on the rear tire in the past two weeks and haven't yet added the weight of panniers.  This is a 24 spoke wheel and I'm told Trek doesn't have a 32 spoke wheel for this application.  I'm concerned for when I begin my cross-country touring in another month and adding another 30-35 # over that wheel.  This Trek model is new this year...anyone else out there have similar problems? I've traveled 1000s of miles without broken spokes until now.  Any diagnosis?

NOTE - Trek has issued a recall for this particular wheelset

Trek Recall Notice for Bontrager Approved TLR Disc 700C 24H Front and Rear Wheels

To close this out and give an answer specific to this model of bike; no this is not a usual amount of spoke breakage, Trek have issued a safety recall notice for this wheelset based on the rate of spoke breakage and the risk of the broken spoke then getting caught in the brake caliper which could then cause a serious accident.
Trek issue this warning:

DO NOT RIDE YOUR BICYCLE UNTIL THE WHEEL HAS BEEN INSPECTED
If you break a spoke, it could engage the brake caliper and you could be
involved in a serious accident. Do not ride this bicycle until your
dealer has inspected the bicycle to determine if it is affected by
this recall.

All the details can be found here:
Trek Safety Recall Notice for Bontrager Approved TLR Disc 700C 24H Front and Rear Wheels