Why does a bike frame have to be above 56 cm usually to fit 700c tires? I first came across this when I was looking at the Surly LHT, but I started to see it everywhere. It seems to me they can just put on a longer fork or something, or is it more for the back wheel?

The real issue is in the top tube length.  Basically, for shorter riders you need to move the handlebars closer to the seat.  But then you have to deal with the wheel possibly colliding with the pedals ("toe strike"), changing the head angle or the fork's rake, which compromises the handling, and/or having a proportionally longer top tube than would otherwise be indicated by the seat tube length.

Rodriguez Cycles did an excellent multipart essay on choosing between 650c and 700c wheels for road bikes, and the illustrated Cliff notes they provide should prove illuminating.


What kind of bike should I rent? I'm just looking to rent for a weekend away. I really know nothing about bikes and could use a hand selecting something that would be suitable for riding in the countryside and not be in complete agony?

There's a list here i'm looking to rent from (as i have money off)

Any help would be appreciated!! Thanks!

Quite a few different bikes there, but seeing as it is based in london, i assume you will be using the bike in mostly urban and city landscapes. My personal opinion would be to go with one of the many "Hybrid" bikes listed. Like one of the flat bar road bikes. If you go full road bike, you will be in "attack" position the entire tire and i imagine you would be more comfortable in an upright position where you can take in the scenery as well.

One thing to look into is what sort of insurance or theft policies are there? Parts of London could be a sketchy place to leave a bike so i would be sure you know the rules and liabilities involved with renting someone's bike. Also would be smart to inquire about repair services or rules if you were to get a flat or other issues.

Next, as others have mentioned, match whatever bike you choose with the type and length of riding you intend to do. A cruiser may be super comfortable for short jaunts around the block, but if you plan to put a lot of miles in, the comfort will loose it's bonus to expending extra effort.

Also, i would avoid an older model being new to bikes. You will likely want a full range of gears and easy to use simple components like trigger shifters.


Can I use rimless tape with an inner tube on a regular (tube style) rim? The plastic and cloth rim tapes at my LBS come in a couple of sizes: too narrow and too wide. Too narrow barely covers the spoke holes (meaning, it doesn't). Too wide gets into the bead area, making it (slightly) more difficult to mount a tire, and worse, it catches on the tire when I mount or dismount it, and when I check the mount to make sure I haven't pinched the tube. Both plastic and cloth tapes move laterally, potentially exposing spoke holes. Aamof, the cloth rim tape I installed a couple of rides ago has already shifted a little. Once off center, both cloth and plastic tapes take a set, making them tend to stay off center.

Tubeless tapes have an actual adhesive backing, as opposed to the tacky stuff on cloth tapes, and nothing at all on the plastic ones. The adhesive should keep the tape from moving (right?). Some tubeless tapes are also very thin, so are unlikely to be pushed off center by the tire during mounting/dismounting. Obviously thin tubeless tape can take the pressure, but I don't know if will adequately protect a tube. Has anyone tried using tubeless tape with a tube on a tube type rim? How about thin tubeless tape?

For what it's worth, I ride 700 mm x 25 mm road tires, 100 to 110 psi. I don't get many flats due to rim tape failure--I check the tape when I repair a flat (which I do way too often).

I have another rim tape question. I'll post it separately. Thanks in advance.

The short answer is yes. Tubeless tape will support using a tube just fine. Tubeless tape does not stretch (much) so the indentation at the spoke holes is very minor.  Remember it is holding back the same force per square inch as regular rim tape, if it gave way the edge of the spoke holes would cut the tape and the tubeless tape wouldn’t be doing its primary job of retaining air. Finally, while the adhesive does a great job of keeping tubeless tape in place, it can still shift  if extreme lateral force is put on the tape (e.g., a very tight tire + tube+ rim combo)


How to replace Avid BB7 brake pads in "new" calipers? How do you get new BB7 pads to install in the new caliper bodies?  By "new" I mean the ones with the spring steel "cap" on the opening at the "top" of the caliper unit (the side opposite the axle).

On my c. 2004 Gary Fisher, the silver calipers are closed on the side opposite the axle.  On my 2015 Salsa Vaya the black calipers have an opening on that side, and they have a spring steel cap that clips into the opening.  The upper "ears" on the pads extend up into that space.

Here is what it looks like from the "top" (looking toward the axle):

You can see the pads through the opening in the cap.

On the old Fisher, I would install BB7 pads just by pinching the pad-spring-pad "sandwich" and pushing the sandwich into the caliper from the "bottom" (the side toward the axle). This is how all the advice on the web tells you to install BB7 pads.  On the Salsa Vaya, with the cap installed, I can only get the pads all the way in about one in fifty tries--usually one or the other pad will not go all the way in.  Sometimes both pads hang up short. If I take the cap off, then the pads go in fine.  I rode all the way across the U.S. with the cap off because that was the only way I could get the pads into the caliper. What's the trick?

There is a trick: The pads need some "persuasion" to get past the spring clip.  Here is a side view of the pads and the spring clip showing how the pads nest within the steel clip.  This should make obvious why a little force is required to get the pads to move fully into the caliper.

After much frustration, I finally looked at the pad and the clip in that side view and realized that the "ears" on the top of the pad need to be forced (gently) past the narrow, re-entrant part of the cap (expanding the cap outward as they pass).  The force required was more than my fingers could muster, and more than was implied by the instructions I found on an Avid site and elsewhere.

The way I applied the necessary force was by setting a drive pin across the edges of both partially installed pads at their bottom (next to the bottom "ears") and giving the drive a light tap with a plastic or rubber mallet. The pads moved ever so slightly as the ears pushed past the re-entrant portion of the steel cap. A piece of wood or a dowel of the right dimension would be better, and a steel hammer would work fine. No matter what you use, be gentle.


Why do my handlebars wobble left and right? I got this bike secondhand, and so I don't know its history/what could have made it like that. And I mean they wobble while I'm holding them, not while I'm riding hands-free only. I've ridden a few bikes before, and they didn't have this wobble, so I don't think it's just a case of me not being strong enough to hold the handlebars straight.

Different bikes can have different geometry. The head tube (the tube that continues the line of the front forks up to the handlebars) angle has a big effect on how the bike handles.

A steeper head tube makes the bike more "twitchy". You can feel like you're all over the place. A bike like this would be a more serious road bike, and if you are used to using flat handlebars then it probably has narrower handle bars (drop bars) also.

Both of those make it harder to control, until you get used to it.
So my advice is: keep trying, it will get easier.

For more reading see

Frame geometry
Explaining the effects of frame geometries
Geometry of bike handling
What effect does head tube angle have on a bicycle?


How to carry a concealed firearm on a bike? For those of you that happen to cycle through rough neighborhoods and are able to do concealed carry of firearms...  Wondering what you wear to conceal them that works well while cycling.  Obviously the standard cycling outfit isn't going to do any good whatsoever...  Various back/fanny packs seem like they'd be inconvenient.  Most jackets that would work fine while walking would tend to "ride up" I'd think.  Just curious as to what works and what doesn't work.

A thread on this subject on Bikeforums ran to pages and pages...   Some expressing utter horror that a bicyclist would feel the need to be armed, others ridiculing the whole idea, others with decent suggestions.
I'm a cop, I know that numbers of cyclists ride in conditions that are less than optimal.
We have had armed robberies and muggings of cyclists here in St. Louis, usually the bad guy is after the high-end bike.
As well, mountain bikers have been attacked by cougars in Western states.  Bicycling magazine detailed several such incidents while I subscribed.   Rare, but possible.

First up.  Having the weapon concealed on the bike is rather a bad idea if the intent of the bad guy is to steal the bike...  Your first indication of anything wrong might simply be a pedestrian knocking you over at an intersection.  Now, he's got your pistol too...

Unfortunately, cycling gear isn't much designed for concealed-carry.  I have a little Taurus 2" 38 special as an "off-duty" weapon.  Drops right into my jersey pocket.
Sure, it "prints" there.  But then, I'm a cop...I don't care.
A reasonable idea is the "fanny pack" (I've just been informed that Aussies call them "bum bags"...).
As far as I know, you can still buy a fanny pack that is designed specifically to carry a firearm....


Shimano FH-6800 rebuild or replace? I just bought a used 2016 Specialized Diverge Pro. The guy that sold it to me told me that he'd recommend replacing the bearings in the rear hub.

I believe the free hub is an FH-6800 (Ultegra). Any thoughts on rebuilding versus just buying a new one?

Also, if I do buy a new one do I need to worry about the thru-axle size? I can't seem to find a definitive source for Diverge Pro thru-axle sizes and am concerned about buying the wrong hub.

Thanks!

There are no thru axle FH-6800 or WH-6800 versions. The next/new Ultegra will have some, but as of now I don't think think any thru axle hubs or wheels that say Ultegra on them are really out in the wild at all.

This bikes uses the SCS dropout/hub/axle system. Long story short, in the past couple years it was unclear what road thru axle standard was going to become dominant and manufacturers had to make decisions with incomplete information to ship bikes on time. 12mm road thru axles with spacing of 142mm in back and 100mm in front have more or less won out, for now. SCS was a competing standard whose history you can find read more about here and here (this page also offers the rundown of wheel compatibility options, which is complicated but basically you can either use one of the few SCS wheelsets/hubs out there or use adapter dropouts, which can have issues with cassette clearance, and which may have already been done on this bike if it's got some kind of Shimano wheelset).

If it is a Shimano wheelset or hub, the situation is the same as with any other Shimano hub. They can be overhauled, ideally on a preventative schedule, and if done faithfully they can last a long, long time. If it's not done, or done too late, they can pick up damage to the non-replaceable or expensive to replace parts, making perfect adjustment impossible and starting the internal condition of the hubs on a downward spiral because of it. When you overhaul Shimano hubs, you have the option of whether to replace the individual ball bearings with new ones. Many of us do it by default but some find that just re-using them, especially on the high-end ones and only in a situation where no damage to anything is apparent, is fine. To replace the ones on the DA, Ultegra, etc hubs that use a plastic retainer, usually the convenient thing is to gently pop new ones into the retainer and re-use it, after cleaning it thoroughly.

A random seller recommending to replace the bearings on a Shimano hub could also be a veiled way of saying that the bearings feel gritty/notchy, in which case the hub internals are likely already damaged.

If they're trying to say the bike is having actual freehub issues (the freehub body itself is acting funny, i.e. getting stuck or not freewheeling at all), the options are usually either replace it, which is expensive for the higher end Shimano hubs, give it some flush/lube type attention, or go to the extreme of actually dismantling, inspecting, and overhauling the freehub body, which is an arcane thing that almost nobody does and requires some special tools.


new MTB creacking on hard pedaling When I press down hard on my right foot trying to go fast or up a hill I hear a noise coming from my bike. What is this? Its brand new... If it isn't an easy fix I will take it back. It only happens with my right foot and when pressing down hard...

Oh also on my wife now bike if you press too hard on each pedal there is a creaking noise. What is this? sounds something is not lubed. It is a new bike also.

Thanks in advance.

If only one side is creaking, it's probably the pedal or crank arm not screwed tight. So first tight them up (for the pedal you probably need a special wrench, for crank arm it's a 8mm hex or 14mm wrench). You should tight it as fast as you can, as it can brake the crank arm.

When both sides are creaking, it could be that both sides are loose, but it also can be a problem in wheels i.e. spokes are loose, or hub is broken, or it can be the BB.

Those are the much common problems, but as @mattM linked at sheldon brown, it can be other things as well.


1x10 drivetrain against 1x11 drivetrain on mountain bike What are the advantages/disadvantages apart from the obvious loss of one gear in the middle somewhere if both drivetrains start and end on the same size cogs

You get an extra gear ratio and closer spacing of ratios with 11 speeds. 10 speeds drivetrains weigh 1 sprocket less I guess, and 10 speeds chains and cassettes are cheaper too.


How are these trikes able to spin around backwards? I found a video of some trikers who start out going backwards, but spin around to moving forwards (watch just the first 10 seconds). As best as I know, my trike can only go forwards. How is such a trick achieved?

They're back pedaling as they go, this lets the drive train move backwards.

You'll often see BMXers doing the same, you see more in the first part of this video.


What sort of wipes should I use to clean a bike with disposable wipes? I'm the sort of person who doesn't have time to clean his bike after every ride in the rain. It occurred to me that there are probably 'bike wipes' like there are for everything else these days that can help me just give the bike a once over super-quick. There are, but then I started reading a lot of people use baby wipes to do the same thing.

Are baby wipes the way to go, or should I be buying de-greasing 'motorbike' wipes etc? I do plan to lubricate parts that need it afterwards.

Ideally, I'd like a wipe that's safe to use on the frame and that can remove grime from drivetrain too.

Of course you may use moist wipes. Although, it certainly is not faster than very quick and rough techniques, for example, simply pouring water over it.

Using wipes is certainly less effective than pouring water over the bike, flogging it dry with an old rag and wiping of the drive train with another one.

A thorough cleaning may be done in three-and-a-half minutes.

Finally, there is the amazing panacea to all our muck related problems, the jet wash!


Bottle holder - aluminium or titanium bolts? I'm a "weight-weenie" and optimize the bolts I'm using. Replacing steel with aluminium or titanium, depending of the location (to summarize: exerted forces, and dangerosity in case of breakage). Aluminium if possible, otherwise titanium.

For the bottle holders (two M5 bolts for each holder), people (fellow weight-weenies) say these bolts are amongst the less stressed, and aluminium can be used without problem. Some even use nylon bolts.

Though, I don't "feel it". Actually, I'm already using aluminium bolts here for months, and it seems to be okay. But these aluminium bolts are really lightweight, and I still fear they might break. Thus, I'm considering using titanium bolts here.

Do you think I am overfearing about the aluminium bolts and they are really sufficient, or not?

(FYI, I put a 500ml bottle on each holder, and I do city/road cycling, of course with some bumps here and there.)

i always avoid aluminum fasteners wherever possible due to a lot of bad experiences with them disintegrating over time (especially nipples on fancy wheels), but i'm not a weight-weenie, just weight-conscious.

i would say if you can afford ti bolts that'd be what i would go for, even though it's overkill and you'd be shaving maybe 1/10th of a gram. of course, if you were truly a weight-weenie, you'd leave off bottle cages entirely, right? ;)

if you're using this bike on a trainer, definitely avoid aluminum fasteners, as your bike is bound to be covered in sweat that'll accelerate the corrosion on the bolts. the things i've seen on trainer bikes.... disgusting. weight wouldn't be much of an issue on a trainer though so i imagine you'll be riding it in drier conditions.


Shimano RS505 freehub body replacement I need to replace the freehub body on a RS505 hub but I can't find the FH-RS505 hub for sale anywhere.

I've checked the Shimano compatibility section for this hub. It looks as though all the freehubs under the FH/WH are compatible with the RS505 hub. Is this correct? If not, which freehub bodies are compatible with this hub?

The compatibility charts don't deal with physical compatibility of replacement freehubs. They're for more broadly which components are compatible together. Replacment freehub compatibility has to do with overall length, shell interface, axle type, and the profile (shape) of the races and the sealing parts. There is a lot of cross-compatibility within Shimano but there are stumbling blocks too. They do not make it easy to figure out.

Here's the basic procedure:

Find the exploded view document for the hub model. Usually this
starts with just googling 'fh-rs505 ev'. In this case that works
fine, the first result is currently a third-party site that as a
public service puts up all the ev pdfs from the yearly technical
manual releases.
Find the 'freewheel body unit' part number, in this case Y31F98080. That is the Shimano part you want if you can get it.
See if you can find someone selling that exact part number. This is hit or miss. Here it's a relatively less commonly seen hub model. I do see a couple sellers around the world that have it, so maybe that's the end of the trail for you. That also implies that Shimano is selling it aftermarket to vendors, or at least did at some point, and/or at least in some countries, which means check in with your bike shop who can login to Shimano's b2b site and see if they can order it for you.
One of the things that gets tricky is that for some insane reason, the part number listed on the ev pdf sometimes has a hyphen or a space inserted in other mediums, so you kind of have to search for it a couple different ways to know you're going to see it if it's there. For example sometimes Shimano would list the same part number as 'Y31F 98080'.
If you can't get hold of the exact part number, then you get into the world of finding a replacement that's physically compatible with the shell and the axle type (standard M10x1 versus proprietary oversized), and jumping through the hoops required to make the other parameters work. There are some other questions that cover this, but basically you have to worry about whether your existing FH-RS505 right side axle hardware (cone, spacers, seals) are going to play nice with whatever freehub body you find that can go on the shell, and then when it's all done you have to worry about the spacing and dish of the complete wheel, which will change a little if certain dimensions of the new freehub are not physically identical to the old one. Often this just means buying all new drive-side axle hardware to match the new freehub body. That can be overkill but it's usually what I do for people to ensure there aren't problems down the line. There are aspects to it that aren't really possible to judge reliably by eyeball. In some cases you'll be able to use the ev documents to find a surrogate freehub that uses the same cone and seals as the old one.


What does error code 30 signal on a Bafang electric unit? A year or so back I bought an electric cargo bike online. The company I bought it from is since then no longer in operation. Since a few weeks every now and then the display shows a wrench symbol and the number 30. At the same time the battery charge indication indicates an empty battery. The bike is still normaly operable. I think this is some sort of error code.
Unfortunately I don't have any manual for the electric components of my bike, so no way to find out myself. I visited a few local bike repair shops, and no-one is familiar with the brand of electric assistance my bike has, and are unable to provide any help.
The label on the electric unit states "Bafang", which I guess would be a Chinese brand.
Does anyone know what this error 30 could mean?
Here is a picture of the error:
Doing some more googling I identified this part as the Bafang DP-C07 display unit.
As asked in the comments here is a picture of the motor:

Error 30 suggests a communications problem, a quick google sent me to the manufacturer website with a list of error codes.
Error Codes
I will add more details later if required but for the time being look at the link supplied for more information

It is most likely a simple connection issue.

First unplug and replug all of the connections on your kit including all of the Main Wiring Harness connections (display,
throttle, brake levers) and all of the Motor lead connections with the
Battery and Speed Sensor. Make sure no pins are bent/damaged on any of
the connection plugs and line up the arrows and pins when reconnecting
everything to ensure proper connection.
If Step 1 does not fix the error, check that none of the wiring on your setup is being pinched, especially the cables coming from the
controller. Check to make sure that none of the wiring on your
installation is too taught and is pulling the cables from the
controller.
Open up the controller from the motor core and unplug all of the controller plugs and replug them again ensuring there is no silicone
interference and everything is properly connected.

Info grabbed from above link incase the site goes 404.


Quality saddle and seat post I own Scott Voltage YZ 25 for around 10 years. I've been using it daily (city ride mostly). Around 6 years ago, my original saddle, and seat-post were stolen, therefore I had them replaced, but not with the original parts. Here is the old picture of my bike with the original seat:

This year, as I gained some weight, I heard that my saddle would crunch when ever I'd put some pressure on it (road bumps, etc). What I did to "fix" it, was just strengthening the screw connecting saddle and seat-post. It was fine, as it didn't crunch anymore.

Almost two months ago, tragedy happened. As I was riding home, my saddle suddenly broke, and I instantly fell and broke my fibula bone (was left with a metal plate in my foot). When I examined what exactly happened, I saw that the screw which was holding the saddle and seat-post broke in half.

I never thought that this can actually happen. Was I able to prevent it?

My main question is, which seat-post and saddle would you recommend me? Something that would be considered safe, and something that can handle 100kg. (220lbs)

100kg is not super heavy and  well within the range of rider weights that bicycles and bike components are designed for. A decent quality seat and seat post should not break underneath you.

Some saddles probably do have a specified rider weight limit, in the same way the most bicycles do. I quickly looked for some information and found that Fi'zi:k actually explicitly states they have no rider weight limit on any of their products. I also looked at WTB but have found no information at this time.

Looking at the picture you supplied, and the description of what happened, I may be able to offer some insight. The seat in the picture is positioned very far back. If the seat that broke was positioned in the same way, your weight would have been acting behind the seatpost and trying to rotate it backwards rather than pushing straight down on the rails and post. You may have also over-tightened clamping bolt. These two factors would have over-stressed the bolt and caused it to snap.

I guess you fell off the back of the bike behind the seatpost, which would have been fortunate as you avoided being impaled on the post as well as breaking your leg.


Fast touring bike / Roadbike with touring capabilities I am looking for a bike as primary transportation in the South Bay area.
My commute is 5 mi, I like to do overnight trips on weekends and use
the bike for shopping, which will involve occasional trips not longer than 30 mi.

My budget is $1500, but I would not mind to spend less in order not to worry
too much about theft and maybe even get a second bike.

I went to a lot of bike shops, but they seem to be geared
more towards racing or mtb, very few bikes even had rack mounts.

My current favorite is the Novara Randonee 2012
http://www.rei.com/product/816068/novara-randonee-bike-2012
but I am not 100% sure it is the right bike for my purpose.

My concerns with the Randonee are:

-Main concern: Bar End Shifters. I've never had bar ends, but I have the feeling that they
are unsuitable for traffic. I have to go through a few streets with heavy
traffic I don't feel too comfortable in, even without taking my hands off the
brakes. I like integrated shifters.

-Minor concern: The Randonee is not overweight (29 lbs), but a bit too heavily built for my
purpose. I won't do any tours of more than a few days, most of my use will be running errands and doing tours (not races) with friends who have mostly cross or road bikes. I don't want to be the slowest.

Are these proper concerns? Did I overlook anything? Does one get used to the bar ends?

Other bikes I looked at:

-Novara Verita, $1200: Goes in the right direction, but sitting was uncomfortable
compared to Randonee, and they weren't able to identify the problem in the shop.

-Fuji Cross 3.0, $800:
400318">http://www.performancebike.com/bikes/Product_10052_10551_1094122_-1_400318
I have doubts about the canti brakes, especially when wet.

-Salsa Vaya 2, $1700: BB5 disc brakes probably better than brakes on Randonee, far too expensive

-Fantom Outlaw, $999:
http://www.bikesdirect.com/products/motobecane/outlaw.htm
Cheaper version of salsa, but bad idea to buy without trying it out.

Anyway, these four only have double cranksets with a lowest ratio of 36:32, I am not
sure this is low enough.

Bikes I read about but that I didn't see in any shop: Specialized Secteur,
Surly LHT, Trek, Surly Cross Check

Are there other bikes I should look at that
-take a rack and fenders
-have reliable brakes for all weather use in traffic
-preferably have integrated shifters
-low enough gear

The Surly Pacer is a good choice. My first real bike was a one, and I used it for commuting, training rides, and a two-week tour in Europe. Even though it wasn't "ideal" for training rides or touring, it worked great for me until I was able to afford more specialized bikes. The Pacer doesn't come with as many rack bosses as you'll want (one advantage of the cross-check), but p-clamps did the trick for me.

That said, about your individual concerns:

bar-end shifters are great for touring bikes

they are perfectly fine for traffic, you get used to them faster than you think
they are waaaay less prone to malfunctioning, which brifters are legendary for

30lb isn't really that big a deal for a do-everything bike

the extra 5lb is nothing compared to the weight of the rider and touring equipment
steel is probably the best choice for this type of bike regardless
it's easier / cheaper to upgrade the engine instead of the bike :)


Cannondale Synapse 105 chain dropping on the last gear I just bought a new Cannondale Synapse Carbon Disc SE 105 and I am having trouble with the chain dropping on gear 50-11.

If I shift on the front chain ring to the biggest ring (50t) and in the rear to the smallest one (11t), the chain drops to the outside of the chain ring under  load after a while. If I rotate the crank manually without load I can see that the the chain is jumping up on the chainring teeth.

It seems like the front chain ring should be 2-3mm further outboard because the gear teeth catch the chain plates causing the chain to jump.

Does anybody have the same problem? Any tips how to solve it? It is not a problem with the high/low limits on the derailleur.

Thanks

The problem was that some ring teethes were a little bit bent. There have to be some impact somewhere between manufacturer and delivery service (the box was not damaged).

I took it to a bike service and they flatten these teethes and everything is now perfect.


Difficulty maintaining power at recommended cadence. Is recommended or preferred cadence better? I find that it's easier to maintain my power at a lower cadence. For example, 75 RPM versus 95 RPM. I'm using TrainerRoad. Recently, I've experimented with a higher cadence.

On one of the workouts, I could only complete 3 of 5 sets. It felt like hitting the wall which never happened to me before on TR.

During FTP tests, I felt that I could test higher for the interval with a cadence that's almost 10 RPM lower.
See VO2 Max 2 and VO2 Max 3.

Even for a recovery week's endurance workout, my hip flexors surprisingly lasted a little more than enough for the workout. Maybe those muscles were my weakest links.

Is it possible that my legs were heavy, making lower cadence even more efficient? My thigh's circumference is 20" and my shin's circumference is 14.5". My height is 5 feet 7.

Is it better to do an FTP test with the ideal cadence or the most efficient cadence (the one that allows you to produce the most power)?

For my workouts, should I select the cadence that works best for me regardless of their recommendations?

Is it likely that my FTP was too low for a high cadence?

GCN did a couple of videos on the subject (1, 2) . In the first linked video, the presenter said that "what current research seems to point to is that is that people ride at their energetically optimum cadence when they're toward their maximum power output. However, they tend to ride at too high a cadence when they're riding at lower intensity." Also that everyone's different, leg size factors into cadence, etc.

Sounds to me like you should do what your body is telling you to do. You're obviously experienced enough that you're not going to blow your knees out riding stupid-low cadences.


Identify this bicycle: Bianchi I recently bought this Bianchi bicycle as my first re-build project. It's covered in a thin layer of rust but could really look amazing with help of a little elbow grease.

Managed to find a bicycle called the Bianchi L'Eroica which looks very similar, but admittedly this version could be a cheaper version as the seat and some elements do look much cheaper.

Does anyone know what bicycle this is or how I can find out?

Yehtsay

This is going to be a 1973-1975 Bianchi 10 sp. I am able to choose the dates based off the logo used. To me it looks like a Special. However it seems you do not have a lot of the original parts, as this would have come with Campagnolo parts, and unless you are lucky,I am going to guess, those still aren't on this bike.

This is the 1973 Bianchi catalog. I choose the model over any other that look similar because of your "rack attachment" this is the only model sold in celeste that had a fender mount. I am also going to say it isnt 1973, because the fork crowns were all chrome in 73, so most likely a 1975, or you have a non original fork.


How do you install a hub dynamo? I want to buy a Shimano hub dynamo, but I'm encountering problems getting a bike shop to commit to installing it for me if I buy it. So I have a couple questions that I'm hoping some of you guys might be able to help me out with.

Can a wheel be rebuilt replacing the old regular hub with the dynamo?  Or does this require a new wheel to be built?  (I've heard once that it's difficult to rebuild a wheel with a rim that has already been built before).
If you can rebuild a wheel, and the hub is a bit larger in diameter than the old hub, do the spokes need to be replaced/shortened, or can they be still be used?  Is there some guideline or rule of thumb about the length of a spoke as long as they're all consistent?
Is the installation of a hub dynamo the same as a standard hub?  I know that the hub has a lot of moving parts inside, but it seems no different on the outside, and I wonder if there are special steps or considerations when installing.

I appreciate any info anyone can give me!  I feel like these bicycle shops have simply never had any experience with a hub dynamo and their first reaction is just "no".

Edit: As a side question, does anyone have any experience with wheel building?  Is this a straightforward process?  This is something I wouldn't mind learning how to do.  Is this the kind of task where you can destroy a wheel or two in the learning process, or will I just need spend more time adjusting to get it right as I learn?

Briefly:

1) yes, you can re-use the existing rim.

2) yes, you could shorten the existing spokes, but that would be expensive and foolish.

3) The installation is the same except now you have wires so you need to plug them into the hub too.

The main issue is (2). Spokes are usually only reused when the rim is being replaced with an identical rim (usually a new one for a worn one), and even then most wheelbuilders will prefer new spokes. Spokes bend a little as they're built into the wheel, and getting those bends in exactly the right place when you rebuild the wheel is effectively impossible. So you'll build the wheel, ride it a little, the spokes will bend back and you'll have to re-tension everything. Usually more than once. If you're paying someone to do this it's cheaper to just buy new spokes.

It's possible to shorten spokes, there are spoke cutting tools for this. They're normally used to make really short spokes (for putting a dyno hub into a 16" wheel, for example) but these days it's possible to buy spokes online in almost any size. But you could sit there and shorten all the spokes in your wheel. But again, if you're paying someone else to do this for you it will be more expensive than a new set of spokes. The tool is also much more expensive than a set of spokes.

If your rim is in good condition that's the bit to keep. If it is worthwhile, you may be better off selling the whole wheel and buying a new rim anyway.


SRAM GX1 comparability with double crankset I am considering purchasing a bike with SRAM's GX1 11x1 gearing but I would like to switch it to use a double crankset.

Is the SRAM GX1 rear derailleur and cassette compatible with a dual crankset?

The bike says:

  This frame is compatible with both 1x and 2x drivetrain setups.  A removable direct mount front derailleur bracket allows for clean 1x build.

Edit: The Compatibility Map 2016 MTB Components is here.  Still trying to figure out how to read it...

According to the chart, The GX long cage derailleur is good  for an 11-42 cassette (Yellow triangle) and a 2x11 crank set (Light blue triangle). Also according the chart, all 1x11's should already be long cage derailleurs, but you may want to check the bike before you buy to be sure.


How do I remove the front axle from a sealed bearing hub? I'm trying to remove the axle from my front wheel to fit it into a box.  But the axle doesn't want to come out.  I've been able to take all the bits off of one side, but I can't remove the ones from the other side, the axle is just spinning while I try and unscrew them.

I expected after I had got one side free that I could just pull it out, but it is not coming out.

I'm not really sure what to do next, every video and explanation I can find on this says that it should just come out.

The wheel has sealed bearing that are pressed into the hub. Your axle is likely being held in by the bearings. The axle has flanges on the inside that the bearing is resting against. You can try tapping on the end of the axle with a soft faced hammer or even a block of wood. This should dislodge the bearing from the hub. This will also damage the bearing. I would look for a larger box and avoid the hassle of buying new bearings and the tools needed to install them.


How to calculate rigid fork replacement for suspension one? Let's say I am reading spec for 29er with suspension fork and I would like to calculate replacement parameters for rigid one. Calculation is needed because I don't want to change geometry after replacement -- so the rigid fork should feel (in sense of geometry) as locked in neutral position suspension fork.

How to do the calculation, what parameters are important? Example:

  "Custom SR Suntour XCT 29, w/ custom Multi-Circuit Damping, alloy
  lowers, coil/MCU spring, Hi-Ten 28mm stanchions, 1-1/8" steerer,
  hydraulic lockout w/ preload adjust, disc mount, 100mm travel"

(text from Specialized Rockhopper 29).

Background 1: I want to do calculations before I buy the bike to avoid situation, that I am buying popular bike but there is no rigid fork replacement (or it is very hard to get).

Background 2: In reality I wanted to buy fitness bike (100% rigid, disc brakes, 700C) and mount wider tires (2"). After some query it appears that all fitness bikes (like Trek 7.2 FX, Cube Hyde, etc) have so little space that you can fit 1.75" tire max (Kross Seto). I found only single bike so far with frame for wider tires (Sulry Ogre), but it is out of reach for me (Poland). So I see no other option as do more expensive replacement -- instead of buying fixed fork bike and replacing tires, buying 29er and replacing fork.

If you want a rigid fork for a 29er with shocks just buy a fork for a suspension corrected frame.  If the fork is listed for a mountain bike then it is (probably) suspension corrected.  I suspect that about any rigid fork that will take a 2" tire will be suspension corrected.

Measuring is not going to do you much good as you can't buy custom lengths (that I am aware of).

Below is a suspension corrected rigid - see the space at the top:

For a workout bike I don't get why you need 2" tires?  You are going to have trouble finding road 2" tires.  There are some rigid mountain bikes (Niner Ross 9 Plus) and also the Salsa Fargo.  Another option would be to buy a used mountain bike priced right because of a worn out shock.


Why are bicycles triangulated at the back but not at the front? I know that triangulation of structures makes them stiff. Why are bicycles stiff at the back but not at the front?

Forks on bikes and motorcycles do pay either a weight or stiffness/strength penalty for their lack of triangulation. One can imagine systems for steering the front hub with a linkage rather than a conventional cantilevered fork. That sounds more heavy and complex than it's worth for a bicycle once you have it able to handle the full range of motion needed, but that's just a guess, and it's not say there's not some other application for such an idea.

One piece of the answer is that the main drawback to a cantilevered fork is that they're vulnerable to being smashed into things head-on. If all else was equal that would be a nice vulnerability to eliminate, but it's hard to imagine a situation where all else is equal, especially considering the forces the bike encounters in such incidents are quite high. Good forks offer a degree of valuable micro suspension even if they're not suspension forks, and losing that just to be able to smash into things would not be a welcome compromise for most.

This is to say that a more triangulated design employed in a way that increases stiffness likely would be unwanted. If you could keep it at the same stiffness but with less weight, I would say the main reason that doesn't exist is no one's been able to figure out how.


Pinion gearbox + Gates belt drive - what are my options for 36-hole rear hubs? I currently have a touring bike with 36 spokes front and back, in the front with a SON 28, in the back with a Shimano Deore XT hub. I plan to switch my frame and I'm currently considering switching to a Pinion P 1.18 or C 1.12 gearbox with a Gates Carbon belt drive.

I thus researched what my options are for Pinion-specific single speed rear hubs, and Pinion itself only offers 32-hole rims. Also, the DT 240 are also 32-hole only. It currently looks as if my only option is a Deore XT or DT 540 Tandem hub with spacer rings to keep the rear sprocket in place. I've also found BMX-specific hubs, but I'm unsure if they are suitable for my needs, as I'm unsure if they have a freewheel ratchet mechanism.

Although I might change rims (26" -> 28"), it would end up silly having 36 spokes in the front and 32 spokes in the back. Do you know of any other options than standard hub + spacers? I should mention that I'd like to keep my 36-hole SON 28 and also not lace without using all holes, mainly because Roger Musson advises against that.

Hope Pro 4 Trial/Singlespeed Hub is available in 36 hole configuration.

Here is a link to the product page:
https://www.hopetech.com/product/pro-4-trialssingle-speed-rear-hub/

You should be able to source them through your local bike dealer or via the internet. The are available for quick release and 12mm axles so you should be able to fit them to your new frame.


Small amount of wobble in wheel If I grab my [suspension] forks tightly and push against the wheel sideways, there is a slight amount (few millimeters on 26" wheel) of play/wobble from the axle/hub. The QR is done up tightly. Is this normal or does it require a hub service?

If you can feel any play ("rattling" sensation) at all in the wheel bearings, headset bearings, or crank bearings, then they need to be adjusted at the very least (and may need rebuilding).  (But please do make a distinction between movement due to looseness in the bearings and simple flexing of the wheel or other parts because you're pressing on it so hard.)

Adjusting is something you can do yourself with a few inexpensive tools, a little mechanical ability, and some practice, but you won't get it right the first several times you try, so best go to your local bike shop unless you really want to learn how to do it yourself.

Standard loose-ball wheel bearings need adjustment every 3000 miles or so, and should be rebuilt (cleaned, new grease, and possibly new balls) roughly every 10 thousand (or more often, if subjected to severe conditions).


Bike advice quick release thru axle lever videos included my thru axle was installed for the last time before breaking here
the installation thru axle before it broke

then after me explaining in the video and the issue as it stands now.
the issue

im looking for a solution to get this axle out, plan to go to shop monday.
the issue written which can be seen and heard in above videos.
Installed the thru axle i always do, attempted to take it out at a stand. the axle level came off, screwed it back on it just came off again.
im looking for a solution on how to remove  the axle out if anyone knows how.

It does not look good.
You may be better letting a shop give it a shot vs. risking damaging anything else. I am sure a good shop has seen this more than any of us here and will be able to try to get it out without damaging anything else along the way.
In the forums I saw it seemed like some drastic things had to happen like cutting hubs, etc.


Replace a Sram x7 trigger lever? I broke the lever of my shifter (SRAM X7) when I fell off my bike on a trail. I think it just fell off the unit. I can see where the lever is connected to the mechanism that pulls the cable. Can I replace just the lever, and not have to buy the entire shifter?

It's extremely unlikely that you will be able to buy parts for a cheap shifter. The whole unit costs $US25 with free shipping.

Imagine you could buy just the lever wholesale for $3. Then you'd pay the wholesaler $3 to find it and pack it for you, then the $3 postage cost. So your "$3" part is going to cost you $9. Plus you're probably going to want the mounting parts for that lever, but they're unlikely to be available separately (the economics get even worse for 2c screws), so there will be a kit of parts including the lever, ratchet mechanism and whatever attaches it to the body. But that kit costs $10 plus the $6 S&H. So you have saved $9 over buying a whole new lever.

Now the shop cuts the old cable off the bike, installs the new parts, new gear cable and outer, and set everything up. Which is about $20-$40 of labour, plus $10 for the cable and outer.

The total cost is about $16 + $10 + $20 = $46-$66. Or $55 for a whole new lever, fitted. New whole lever is an easy job, taking apart the old one is tricky so will probably take longer.

From a bike shop's point of view that's a $9 saving in exchange for the risk that you're wrong about how much damage was done. If the pivot that that lever sits on has bent the repaired lever won't work properly. There's a whole range of problems like this, but you as the customer won't care, you will just come in and say "you fixed it, but it doesn't work". After the first time this happened they stopped doing it, and only fit whole new parts.

So bike shops will not order the "parts kit", only a few keen cyclists who do their own repairs will. Instead of selling hundreds of these kits, SRAM will only sell ten. And maybe another ten next year. Or not, since the overhead cost of each product is non-trivial and if something is only going to sell a hundred units at $10 they're not going to bother.

Which is what you see happening.


Very basic mudguard question I have mudguards on my bike as shown here:

Firstly, I don't even know what the metal spoke-like things attaching it to the bike are called. Do they have a name?

Secondly, what do I need to attach them back to the bike. From the non-broken ones it doesn't look like a normal screw, but again not knowing the name means I am not getting very far with google.

Lastly, out of interest, is there a name for this type of mudguard and is it an old/out of date type of mudguard.

Mudguards (typically called fenders in the US) are a great feature and come in many varieties. The fenders you have are full-coverage fenders and are likely aluminum. Metal fenders are still quite common (and in my opinion, fenders are an essential addition to any bike if you live where it rains. Velo Orange manufactures many sizes and styles that are affordable.)

The fenders are held to the bike via fender stays (long aluminum rods) and are mounted directly at the fork crown in the front and the brake bridge and chainstay bridge/bottom bracket shell in the rear.

Fender stays are usually mounted to threaded bosses (with an M5 or M6 cap screw) integrated into the front and rear dropouts (or near the dropouts.) In situations where you don't have dedicated bosses, you can use p-clamps to mount them securely.

At the other end of the stay there is a nut and an eye bolt which allow the distance between your tire and the fender to be adjusted (10mm minimum!) Note: There are many different methods for attaching fender stays, but this is what your fenders utilize.

To install, you simply put the eye bolt onto the fender stay, push the threaded part through the hole on the mounting tab, and tighten the nut down to secure the stay. Do everything loosely at first, then adjust the distance from the fender to the tire and center it.

Here is a link to an online vendor, but most bike shops will have this hardware on hand.


Which Phil Wood bottom brackets are compatible with Shimano XT cranks? As far as I can tell just the Outboard BB is.

According to the Phil Wood FAQ:

  What is the difference between JIS, JIS low profile, and ISO
  tapers?
   Phil Wood offers all three tapers to try and best meet the needs of our
  customers who are using square-tapered
  bottom brackets. An explaination of
  the different bottom bracket tapers
  can be found here. In brief, most
  modern cranks will take the JIS
  (Japanese Industrial Standard) taper,
  in addition to Campagnolo cranks
  produced before 1994. After 1994,
  Campagnolo moved to the ISO (a.k.a.
  Campy) taper. The less common of the
  three tapers offered is the JIS low
  profile, which is used in some
  specific older-model Dura Ace cranks.

Since Shimano square-taper cranks are J.I.S. (not low-profile), this means that all Phil Wood bottom brackets with JIS spindles are compatible, as well as Outboard Bottom Brackets.


Is it ok to use fixed gear threads for a freewheel? I have a fixed/fixed flip-flop hub and the lockring threads are stripped out on one side. Would I be ok to just thread a single-speed freewheel on that side and use it as a fixed/free hub?

If the thread fits, there would be no problem.

The nature of the mechanical stresses over the hub during traction would be identical (only there would not be the backpedal component, but that means less stress, not more).


How to distinguish a 26 inch fork from 28 inch fork I have a 26 inch MTB frame and I want to replace the fork.

How can I distinguish a 26 inch fork from a 28 inch one? Which are the measurement to know?

thanks!

Suspension (or rigid) forks are not designed just for a particular wheel size, instead they have a nominal crown to axle length. Frames are built for a specific length fork (or a range of fork lengths) that will give the proper head tube angle. This takes into account both wheel size and length of suspension travel.

Forks designed for rim brakes will of course have attachment points located correctly for a particular rim diameter. (Credit to RLH for reminding me of this in a comment.)

This gets a bit tricky with suspension forks, as obviously they are designed to change length and may extend beyond their neutral length without a rider on the bike.

Measure the crown to axle length of your current fork and look for a replacement based on that, length of travel (and rim brake boss location). AFAIK forks for 26" wheel bikes with short suspension travel (>80mm) are not available new (commenters please prove me wrong on this).


Why only ball bearings on bicycles? In general, ball bearings are applicable in higher speeds because of the smaller contact area and smaller friction force, but roller bearings can carry greater loads because the load applied to the contact area produces smaller contact stresses.
   -- Principles of Mechanical Engineering Design, Liubomir Dimitrov

In bicycle applications there are neither high speeds nor high loads (compared to cars or industrial machines). However, I would assume that the "smaller contact stresses" would result in significantly longer service life of the bearing, even if water and contaminants penetrate the bearing. And still the only time I have heard of bicycle roller(pin) bearings is in the hyped Lefty.

Why are ball bearings used exlusively in bikes e.g. in the headset where some minor friction would not be a problem?

I think several of your assumptions are incorrect:

no high speeds: rim dynamos spin quite fast, up to 10,000rpm, and that does require effort on the part of the designers. Typically the drive wheel on those will have a radius of about 1cm, or a circumference of 3 1/3rd cm and 30 revolutions per metre. At 10m/s (30kph) that means 300rps or 18000 rpm. This is why they make such a high pitched whining noise when in use.
no high torque: a 100kg cyclist standing on a 165mm crank is exerting about 1kN at 0.165m, or 165Nm. That's comparable torque to a mid-range car. I repeatedly snapped a 8mm high tensile  bolt in the drive system of my four wheel load bike, and replacing that with industrial freewheels meant buying two of the highest rated units I could find (German conveyer belt parts rated to 250Nm)
No high loads: a touring cyclist with 50kg on the rear rack, plus half their 100kg body weight is putting a load of 100kg or 1kN on a 10mm diameter hollow rear axle. Those axles and the dropouts they bear on must be made of hard steel to stand the load, where the load bearing parts of a car or truck are typically made of much softer steel.
Only ball bearings are used: modern sealed bottom brackets commonly use roller or needle bearings, as do many headsets. Internally geared hubs have used needle bearings for many years. Sheldon Brown describes roller bearings in his glossary, for example.

The answer is that various types of bearings have been used in bicycles and will likely continue to be. Again, Sheldon discusses needle bearings in Shimano hub gears from some years ago and they're still mentioned in the marketing.

One problem not unique to bicycles but especially relevant to them, is that more precise bearings are more vulnerable to grit and also to damage. So especially needle bearings need to be carefully protected from dust, sand, and forces outside their design range. Unfortunately doing that inside a suspension unit is hard, and last time I looked Cannondale had not solved the problem (my HeadShock is unmaintainable after only about 10Mm, I've seen multiple lefty shocks fail during a race because of light rain and fine grit causing them to abrade to uselessness very quickly)

But inside a hub or headset, for example, they can be amazing. I've talked to people who've ridden 20Mm on an Alfine 8, for example, with no problems.


When is it not okay to cheap out on bike parts? Cycling is a very expensive hobby. So I tend to buy stuff not from famous brands like FSA and so on. But is it safe to do that? Cheap handlebars will send me flying like Superman one day. What parts of the bike I should never buy cheap?

There are potentially a lot of ins and outs to this question, as one could ask what discipline you're talking about, how aggressive of a rider you are, skill level, etc, as it all has an impact on how likely you are to be punished for going cheap, and how severely.

However, there's a really good axiom in cycling: "Cheap, light, and strong. Pick two." Your answer is pretty much right there.

An example would be comparing a bottom-end aluminum Shimano road wheelset vs super cheap, unreputable carbon wheels. The former is cheap and strong but not light, and the latter is cheap and light but not strong. For most categories of bike component, there are going to be choices that have a similar relationship. If you want to get by with cheap stuff, this is the angle you have to work. Light components at very low prices, especially ones new to the market, often turn out to be junk, sometimes in a way that can be dangerous (there have been numerous pedals, wheels, hubs, stems, brakes, and cranks in this vein in particular.) Conversely, being really successful at being a thrifty cyclist is usually all about either finding the stuff that's a little less flashy but more stalwart and able to get the job done or just finding good higher end stuff at low prices. Most attempts at "getting away with something" by buying the other kind of cheap stuff are bound to fail.

Some more particulars:

There are a lot of flashy, cheap two-piece cranks running around these days that can have issues with pressed interfaces that are supposed to be permanent coming apart and creaking.
There are some good offbrand carbon rims and some that have proved unreliable. It's a good place to be cautious.
Rear hubs are a component where it's easy for manufacturers to put out something for cheap that has a high engagement rate, smooth bearings, and light weight that then proceeds to totally fail to be a reliable component. It's best to go for something that's either a known workhorse (XT and 105 for example) or true high end, and not roll the dice on anything else.
Cheap, off-brand headsets and bottom brackets are almost always disappointments.

A final note: it's actually a really good idea to pay close attention to how long a given model of component has been on the market unchanged. Bike component manufacturers love having flashy new attention-getting things and often feel pressure to change up their lines at least every couple years if not sooner. More often than not, when they keep the same model kicking around longer than this it's because it's just a good design and has earned a reputation for it, and there are a lot of examples of cheaper components this applies to. PD-M520s, CR18s, and FH-M756s are some examples from the last couple decades.


Can i use a XT 8000 crank instead of GRX crankset I want to lower the gearing in a GRX 800 set up from a single 40 ring to a single 32 ring or use a XT M8000 crank with 32 ring.Im old and slow.Will it work

A single ring is quite easy because there is no front derailleur to worry about.
I assume you have FC-RX810-1, which has 110mm BCD, and uses the same chainrings as FC-RX600-1
Wolf Tooth go to 36t https://www.wolftoothcomponents.com/products/110-bcd-asymmetric-4-bolt-for-shimano-cranks
There are some Chinese 34t chainrings as well
https://www.aliexpress.com/item/4000620134076.html
If you want to swap a XT crank you can but you will need to remove (or replace) your BB and fit 3x 2.5mm spacers  https://si.shimano.com/api/publish/storage/pdf/en/dm/MBFC001/DM-MBFC001-01-ENG.pdf
Then your XT crankset will have slightly (0.23cm) wider chainline and substantially (2cm) wider q-factor


What's a good, reliable mountain bike drivetrain (1x10?) I'm thinking about switching my Salsa El Mariachi 29er mountain bike from singlespeed to gears. I love the reliability and simplicity of the singlespeed, but I've been doing more rides that involve both road and trail riding, so it's tough to find a singlespeed gear ratio that can do both.

I do lots of really long (~75 mile) rides and some multi-day bikepacking trips through the Colorado backcountry, so I need a drivetrain that is really, really reliable. I'm also fairly tough on components (currently, I replace my SS drivetrain each year), so I want to get something that's not too expensive. I currently am running a bashguard (using a SLX triple crank), and I'd like to keep running a bashguard since it's awesome to have one.

I was thinking of running a 1x9, or maybe 2x9 (with bashguard) setup with SRAM X9 or X7 components. But then I read some great reviews of the new clutch derailleurs (Sram "Type 2" or Shimano "Shadow plus") - people are saying that they keep the chain running lot nicer than the old type derailleurs. I've heard good things about running a 1x10 with the new Shimano Zee derailleur. The many drivetrain options are getting a little ridiculous!

So, what do you think? What drivetrain will keep running through the dust, mud, and crashes, while still keeping the price to something reasonable?

Thanks, Dan

I won't suggest any brands but here are some ingredients that will allow you to go cheap and reliable:

go 1x9. 2x is more expensive, more noisy, heavier and generally problematic if you can get away with 1x. Just make sure you calculate some possible ring and cassete options so you know that you'll be able to tackle all ascents and descends you need to. A spreadsheet works great for that. Divide ring teeth to cassette teeth to find the ratios that you need. Ride friends' bikes on ascends and descends for find your numbers.
bashguard: Do you really need it? Please check on your existing one whether you see impacts. Have you used it so far? If not, you don't need one. Especially now that you'll go to a single and smaller ring, chances that you really need one are very slim.
chainring: Go with a "narrow-wide" one. There are at least 5 companies making such rings now. The narrow wide pattern of the teeth allows for maximum chain retention eliminating the need for a chain guide.
rear derraileur: Definitelly go with one which has a clutch mechanism. It does work wonders.
crank: You'll most probably be able to use your current SLX crankset, but I'm not 100% sure on that. There is a possibility that you'll need to do some research and play around with spacers in order to have the perfect chainline so all cogs of the cassette are working well.
chain: If you go 1x9 get a 9sp chain. If you go 1x10 get a 10sp chain.


Time trial improvement from new bike I can average 21.7mph for a 20 mile time trial (00:55:15), on my 2001 Rockhopper with 1.25" fatboy slicks, no lock out on shock. My bike weighs 25.25 lbs. I'm planning on buying a Cervelo 2012 r3, 16.4 lbs estimated weight. I also plan on dropping 4-6 lbs, so my total weight would be about 14 pounds less. Does anyone have any idea what my average speed would be for a 20 mile time trial in good conditions, 10 mph max wind?

You might want to play around with Bike Calculator a little, and you could find a reasonable estimate for your question.

Regarding the new bike purchase, shop around carefully. You're already past what is considered the clearance season for 2012 models at many traditional brick-and-mortar bicycle retailers. Prime time is August/September of each year. That's when many retailers start their clearance sales.


Why is my chain so noisy after cleaning and lubricating? I have recently gotten into commuting to work with a road bike.  Once a month or so I will degrease, clean, and lubricate the chain.  I change through all the gears to distribute the lubricant and wipe any excess from the chain when I am done.

The problem is that for the first 2 or 3 hours of riding after cleaning the chain, my bike is constantly making clicking+creaking noises.  They sound similar to what one would hear if the bike was having trouble changing gears and seem to be coming from the area of the rear derailleur.  I can "feel" the noise in pedals also.  It seems to be most noticeable in certain gears on the rear derailleur (3, 5, and 6) but totally absent in others (such as 4).

After a couple hours of riding the noise goes away and the bike feels great.  What is going on here?

Likely some coarse particles get in between the chain elements and also between the parts of the derailleur and the star wheels. After you cycle for a while those particles either fall out or get crushed into finer particles and thus the noise goes away.


What should I do when my rear derailleur cable guide is too narrow? I am installing a modern groupset on an old frame. The frame has a rear derailleur cable guide like this:

The problem is that the gear cable housing ferrules are too large for the braze-on, causing the cable to sit at an awkward angle.

My gear cables are 4.1mm (standard Campagnolo 11-speed, I think). The braze-on has an inner diameter around 3.9mm.

How should I solve this?

You need a stepped shift ferrule. You have no reasonable options if you're using compressionless shift housing. On the left is a picture of a 5mm to 4mm one, which Jagwire is the main remaining producer of. On the right is the Shimano 4mm one, which in my experience is the commonly encountered one for 4mm housing. There are Campy ones too, but I think they may only come in the Record cable sets - I don't cross paths with them very often and I kind of forget what they're like.

Shops should have them. They're still readily available new in bulk and many shops will have all they need leftover from installing the various cable kits and STIs that come with them. I believe Dura Ace shift cable kits have always had them and at least some generations of boxed D/A STIs too. Googling "5-4mm stepped ferrule" and "4mm stepped ferrule" yields some results too.

Note that there's another kind of stepped ferrule, for using 5mm compressionless brake housing on brakes and brifters that can't take a normal ferrule, which is not the kind you're looking for. The most common example of this is the Jagwire POP ferrule.


Are all gear ratios created equal? Here's a question simple at face value but for the math nerds feel free to dig in. Do all ratios of similar proportion (eg. 1:1, 1.5:1) etc feel the same. As in require the same work? Is the bottom end of a 2x (52/34 x 11-34)
Exactly the same as a 1x (42 x11-42)?

The answer is that yes, a 34t cog and 34t chainring would be the same gear ratio as a 50t cog and 50t chainring. However, the difference would be in drivetrain friction, as this Velonews article demonstrates. Larger cogs and chainrings make the chain articulate less, and these have lower friction than combinations where the chain articulates more. This would be true even if we are considering single-speed or track bikes where the chain is totally straight. Otherwise, the more the chain is angled, the more friction is produced.

Now, would you notice the difference? The testing facility in the Velonews article I linked estimated the the average friction difference between a 2x setup, 53/39 chainrings and 11-34 cassette and the equivalent 1x setup with a 48t chainring was about 3 watts at 250W total input power; 1x systems often have smaller cogs or larger chainrings than the equivalent and optimal 2x gear. The 1x system has the greatest friction in the 48t ring and 10t cog, and this combination has the biggest friction disadvantage to the 2x system's equivalent gear (53x11) at about 6 watts. The next two biggest gears are about a 4-5W deficit to a 2x system. Note that this is all at 250W, and riders operating at lower power would see less of a differential.

Is this difference perceptible or important? In this Cyclingtips review of the Ceramicspeed oversized pulley wheel system, which should be about a 1-2 watt saving, the reviewer claimed he did not consistently perceive a friction difference. In many gears, the 1x system is within 2 watts of the 2x system, so you would be unlikely to notice the difference. In the top 3-4 gears, the 1x system is at a bit more of a disadvantage to the 2x. Nonetheless, the difference even then may not be that noticeable to many riders.

Also, 1x setups lack a front derailleur, which reduces the bicycle’s aerodynamic drag slightly. The Velonews article pegs this at about 3W at 30 miles/hr. This would partially offset the increased drivetrain friction for many users, even those not cycling at 30 mph.

(Edit: note that a previous version of the answer mis-stated the Ceramicspeed system's claimed savings. I remembered that it was 2.4W from somewhere. CS actually claims greater potential savings, but the Cyclingtips article reminds readers that if you are diligent on drivetrain maintenance, you are likely to see only about 1-2W of friction savings from the Ceramicspeed system. If you are not diligent about drivetrain maintenance, then you should be, as it's cheaper than a Ceramicspeed oversize pulley wheel system. Moreover, if you still chose to get one, you would make it last longer with better maintenance - and at the asking price, this would be a really, really good thing!)


Customizing the smallest cog I am running on a Shimano Tiagra 10 speed (CS-HG500-10) (12T-28T) and (50-34T front). I'd like to change the smallest cog (12T) to something smaller, i.e., 11 or even 10, to improve my sprints. Is that a possibility?

Yes you can.
You could need a new cassette screw too, the current one you have will be too big for the 11T cog.
Realistically, the 1T different will not make as much a difference as improving your techique, muscle/power, tyre and air pressure choice and even nutrition.
Make sure the new 11T cog is for Shimano 10s cassette, it might not fit otherwise. Worst case scenario, you can get a complete new cassette, Like a 11T-25T or 11T-28T etc. Plenty of brands available with them.
I don't think you can get a 10T cog on it.


How difficult would it be to maintain 17.5 Mph for an hour? Whats a good target speed to maintain inside a velodrome for an hour? I believe Bradley Wiggins maintained an average speed of around 35 Mph for an hour, how difficult would it be to maintain half that speed for a similar amount of time?

The short answer is: not that difficult. The long answer requires some explanation.

The equations of motion for a rider on a bicycle are well-understood if not always well-known. The power needed to propel a bicycle on firm flat ground (as on a velodrome) varies approximately with the cube of speed. Thus, to double your speed, you would need to increase your power output by approximately a factor of eight; riding at half-speed decreases your power output to approximately one-eighth of full-speed power.

As may be obvious, Brad Wiggins was highly trained and highly optimized in both equipment and position to minimize his coefficient of rolling resistance (Crr) and aerodynamic drag area (CdA). That means even at 17.5 mph he could very possibly use less power than most cyclists would.

That all said, this bicycles.stackexchange answer discusses the equations of motion for a cyclist, from which you could calculate the power required to ride at 17.5 mph on a velodrome using reasonable estimates of Crr and CdA. For most average-sized adults, not highly optimized for position, a reasonable estimate of CdA on a standard pursuit bike similar to but not identical to the one used by Wiggins would be around 0.275 m^2. For this example, then, one could cover 17.5 miles on the velodrome at right around 100 watts of output. In comparison, an average sized man, walking on firm flat ground, would expend roughly 75 watts. So riding a velodrome at 17.5 mph would be more difficult than walking at normal speed for an hour but not horrendously more difficult. However, because of the cubic relationship between speed and power, riding at 20 mph would require nearly a 50% increase in power over riding at 17.5 mph, and riding at 25 mph would require a trebling of power. Many non-sedentary adults can produce somewhere between 2.0 and 3.0 watts/kg for an hour, so such a 75 kg man would be able to maintain between 150 and 225 watts for an hour. As you can see, many (but not all) adults would be able to maintain 17.5 mph, but not as many would be able to maintain 20 mph, and relatively few would be able to maintain 25 mph.


Shimano 105 FD-R7000-F front dereailleur chain rub Recently purchased a new Cube Attain GTC 2020 road bike, it came with :

Front Derailleur -  Shimano 105 FD-R7000, 31.8mm Clamp
Rear Derailleur -   Shimano 105 RD-R7000-DGS, 11-Speed
Brake System - Shimano 105 BR-R7070, Hydr. Disc Brake, Flat Mount
Crankset - Shimano FC-RS510, 50x34T

All seems good, however I've noticed the chain is rubbing on the front derailleur when using the 50T ring on the first 5 gears.
This I take it is due to cross chaining, i know it's not advised to use the opposite sides of the cassette but are they all like this ?

Note : I don't get any chain noise or rub when using the 34T ring in any of the 11 gears on the cassette.

So my question is this - can the front derailleur be adjusted to eliminate the chain rub on the 50T ? or will this effect the indexing on the 34T ring ?

I've read through the PDF from Shimano and they say chain noise is normal, really? can you only use the whole range on one chain ring ?

PDF image below along with the front derailleur.

I'm aware of the high and low screw adjustment but don't want to tweak anything if it's going to throw the indexing out of alignment on the 34T ring.

I don't know about the R7000 in particular, but your FD most likely has a 'Trim' function to help with this.  This is usually activated by light/half click as if you were going to the small ring but not actually doing so.

I'd say if you are getting rub on the lowest 5 gears in the big ring, but no rub at all on the small ring your FD position is slightly out.  It is common to have rub in the 2-3 gears at the extreme ends (small ring high gears, big ring low gears) of the gear range.


Do Seat Posts with Shock Absorbers Help? I have Fuji Absolute 1.9D road bike. Is the seat post on this bike fitted with ashock absorber?  I don't think so. If not, would it be worth replacing the original seat post with shock absorbing one?

Thank you

Your bike probably does not have a suspension seat post.

They are great for smoothing out small bumps on rough roads, and help with people whose anatomy is not 'cycle hardened'. For less fit riders, you do not need to unload the seat by standing for small bumps, so can make a ride less tiring. They also help soften the blow where you misjudge a bump and its bigger than expected.

However, they also loose some pedalling efficiency due to the changing length of the seat-pedals, so few serious cyclists use them.

Most people love or hate them, not much middle ground. People who love them are usually casual cyclists. I have used one on a MTB hardtail, but ride often enough it makes little difference to me. My wife currently does because she rides rarely, and it helps smooth out the bumps on the hard packed MTB trails she rides.

Should you get one? Only if you ride with padded shorts and still want a bit more comfort. if you try one and like it, as you get more miles under you belt, you may find you don't need it, or even dislike it.  It could be worth holding off getting one for a while and giving time for your body to adapt to riding.


Boost 148 and 110 standard specification Where can I find exact specification for boost 148 and 110 axle specification. I was able to find many documents describing main features of it, but I would like to read document with all exact dimensions and drawings that make this standard

MTBR has a pretty good write up about the technical aspect of it that can be seen HERE
From that article come these two technical drawings.

Boost 148 adds 3mm of spacing on each side of the hub. But unlike the 3.5mm difference from 135mm to 142mm, Boost 148 sees an increase in flange spacing, not just axle endcap width.
Boost 110 uses a 15mm thru axle and moves hub flanges outboard by 5mm when compared to 100mm hub standards. This 5mm outboard movement affects the spoke bracing in the same way as the 3mm shift on 148mm rear hubs, increasing spoke angles and creating, “the stiffness of a 26” wheel” in the front as well.
Now here comes the tricky part. With these minor shifts in flange spacing, the brake rotor mount location and the freehub body spacing have to be taken into consideration. Everything is shifted slightly outwards. So newer forks with the Boost 110 standard have also been designed to account for a shift in rotor and caliper location. That’s why Boost 110 is actually different than the 110x20mm thru axle standard that already exists. The 110x20mm hubs seen on bigger forks still have the same rotor mounting as a 100x15mm hub
Rotor shift is simpler than freehub body shift, because now with Boost 148 the chainline has been altered by 3mm. With a 3mm increase in chainline, it is necessary to move the chainrings outboard by 3mm as well. Luckily this 3mm shift can be accomplished with a redesigned crank arm spider. The Q-factor of the crankset and the BB width remain the same. For these reasons we will now see the introduction of Boost 148 specific cranksets that are necessary to achieve proper chainline.
With the shift outwards, the frame is afforded more clearance, which then allows the frame designer more tire clearance and will maintain a short chainstay.


Cause of Oblique Pain When my wife gets done with a long ride she finds that her right oblique hurts, while her left does not.  Does anyone know a possible cause of this, like improper form or saddle fit?

Could be a number of things:

Saddle/cleat/handle bar misalignment
bad form on her right side, not spinning circles, etc

Have you ridden with her and checked out her form? Is she favoring one side over the other?


Marin Fairfax Alp 2011 - Can I fit a 11-32t Cassette I currently have a Shimano LG50 12-25t 8 speed cassette and am finding it a real struggle on steep hills - I am around 13 stone (82kg). This is the first time I have looked at changing the original gear ratios on any bike I have owned.

I want to change to the 11-32t or another cassette but I am wondering if I need a new chain i.e. to lengthen it and also if the rear mech is OK. I ask this as stuff on the interweb says both can possibly be an issue. I believe there may be normal and long leg versions.

The rear derailleur is the original Shimano Sora 8 Speed Rear Derailleur (GS Long Cage).

Current chain is the Shimano Altus HG40 6-7-8 Speed Chain.

Crankset is Truvativ Touro 52-42-30t.

Using the link below it says the rear derailleur will take 37T to 39T or less.
So the current cassette is (25-12) + (52-30) =35T
11-28 is (28-11) + (52-30) = 39T
11-30 is (30-11) + (52-30) = 41T
11-32 is (32-11) + (52-30) = 43T

From this it looks like my only option is the 11-28, which would only give a minimal improvement. Am i wasting my time trying to fix this particular bike as it stands?????

Thanks in anticipation. Kev

Many thanks to you all for your responses. I hope I have learnt a lot around this area and it sounds like I was hoping to achieve too much. I have ordered a 11-28t cassette and new chain as this stays within the guidelines from Shimano for the Sora rear mech. I will be v interested to see the difference it makes.

As suggested by someone, I did a lot of shopping around for a slightly smaller 5 bolt chain ring than the 30T that's on there, but hit a massive blank in finding a Truvativ ring that was smaller. Thanks again to all......UR*s

I think a disadvantage of the 11-32 cassette are the large gear steps. Also consider that switching from 25 to 28 already makes it 12% easier.

You could (additionally) install smaller chainrings, 52 is quite large and instead of 30 you could go down to 28 or 24.

You will need a new (longer) chain if you increase cog size, unless you decrease chainring size at the same time or the chain is currently a bit longer than necessary.  A worn chain will work badly on new cogs or chainrings though.


Can pumps fail due to age? I have a small cache of the now-discontinued Quickex Quicker Pro mini pumps. They have 105 cm3 stroke volume, and 5 kgf force required for 7 bar pressure. In about 100 strokes, I reach 7 bar on 28mm 700C tires. The reason for these extraordinary specs is that the pump has a multi chamber double action design: it pumps even on the outstroke. I am not aware of any other pump with comparable specs. Typical mini pumps require 200-300 strokes for 7 bar, and a large pump such as Silca Impero requires 20 kgf force for 7 bar pressure.
I'm worried that the pumps in the small cache could fail over time due to natural degradation of materials. I store the pumps indoors shielded from sunlight. If all of the pumps in the cache fail due to natural degradation of materials, I'm left with no working pump and no possibility to purchase a pump having similar specs, because no other mini pump manufacturer has realized how to build a mini pump that pumps a tire quickly in few strokes with little force.
Is my worry justified? Can a pump that is not being actively used fail?
Due to their complex construction, it may not be feasible to disassemble and repair a failed pump.

Can a pump that is not being actively used fail?

On the one hand - nothing lasts forever.
On the other hand - you don't need your cache of pumps to last forever. You only need your cache to last:

Until you stop riding
Until you find something else that works as well or better

So, let's say best case scenario, you need your cache of pumps to last 40 years (just picking a number).
Let's also say that you have enough pumps in your cache to last the 40 years (or whatever number you pick) due to normal wear. For example, if one pump wears out every five years you have 8 pumps.
Your question is - will that last pump still work 35 years from now when you pick it up having never been used before?
My bet (in the absence of actual data, which would take longer than I'm willing to wait) is yes, that 8th pump will still work.
Here's why
Your cache of pumps have two things going for them:

The seals are covered with a lubricant that protects them from oxidation
The seals and the lubricant are in a sealed environment

It may be that your real problem 35 years from now will be the oxidation of the lubricant rather than the oxidation of the seal.

Oxidation is the most predominant reaction of a lubricant in service. It is responsible for numerous lubricant problems - including viscosity increase, varnish, sludge and sediment formation, …
Oxidation - The Lubricant's Nemesis

You can increase the odds of in your favor by:

Storing the pumps in a temperature stable environment, as you describe in your question.
Re-lubricating the unused pumps after some period of time (check them at 5 years and set a schedule based on your observation) would assure that the lubrication does not break down and gum up the pump. Re-lubricate the pump with a lubricant that is similar as possible to what you find in the pump.


How do I know if I can replace the 27 inch wheels with 700c wheels on my bike? I recently purchased an 80's Japanese bike off craigslist called "Jupiter King." It has 27 inch tires but I want to switch to 700c for greater wheel/tire selection. I specifically want some nice yellow wheels with yellow rim. Help? I am quite a noob with bikes. Thanks for any help/advice.

You may or may not be able to make that conversion with your existing brake/frame combination. Your brakes will have to reach farther because a 700c wheel is a smidge smaller than a 27 inch wheel. Depending on your setup, that may be possible. I'd recommend borrowing a 700c wheelset from someone to see if you can line it all up. If it all lines up, great. Purchase whatever 700c wheelset strikes your fancy. If not, you may be able to purchase brakes with a longer reach. Some older frames still won't work with 700c wheels even with the longest brakes available. If that's the case for your frame, you're stuck with 27's.

Personally, if it were me and I couldn't get it to work with the existing brakes, I'd stick with 27 inch wheels. If you start having to swap brakes out, it starts to get iffy and frankly, I think it's more hassle than it's worth. It's a lot easier (and maybe cheaper) to just start hunting for a frame that already has 700s on it.


Cracked frame riding into the back of car, what's salvageable? Stupidly rode into the back of a car, due to a moment's inattention. I pretty much hit it at full pelt, though I was riding uphill at the time.

The frame cracked, as this photo shows. Any idea what else is likely to be wrecked? Front wheel? Headset?

edit: Got a quote for a frame repair, for the two tubes, four to six braze-ons and a respray (which is assuming no headtube damage) I was quoted "at least £400".

I've worked on a couple bikes that have had frontal impacts.

Check the underside of the downtube for any abrasions or rubber marks.  You might find the front tyre has touched the downtube in the collision, giving you an idea of how far it bent and has come back.

Theres a fold in the downtube and I can see a completely broken top tube, so

  That frame is unrideable as-is.

The unknown damage could include

Front wheel - Check it for trueness both left/right and up/down.  Take the tyre off and check it over under a strong light looking for cracks or damage.  If its aluminium its probably OK, but front wheel failures break people, so you don't want that.
Bent fork tines effectively reducing the rake and therefore trail and handling.
Fork's crown welds have been stressed leading to possible failure later.
Steerer tube may have been bent or distorted out-of-round which will weaken it.
Bearing cups/cones/sealed bearings in headset - they may be fine or they may have imprinted a dent into the bearing race surfaces with impact.  The bearings themselves may have cracked or flaked or they may be fine.
Steerer top-cap and bolts, and spacers.  These may have taken some level of impact and may be not as round or flat as they used to be. You have plenty there to compare, which is handy.

On the plus side I'd expect these parts to be okay (assuming none of them got crushed or incidentally damaged)  so do check them out first before reuse

Brakes, rotors and calipers, lines and levers.
Handlebars, shifters, grips/tape, Stem.
Lights, reflectors and computer/phone
Everything on the bike aft of the drink bottle.  It might slightly scratched/scuffed from subsequent fall, but there should be no damage from the impact with the car.  So your transmission/groupset will be totally fine.

I note that the bike didn't fail you, so don't write it off.

Also, depending on liability, insurance, and so on you might have to discuss ownership with your insurance company.  They may elect to replace it rather than repair it, if you choose to do a claim for an accident.   Also, the car owner's insurance company may have a say in it too.


How can I make better use of the dead space under my bottle cages? There's an annoying/useful bit of space under each of the bottle holders on all of my bikes; I currently strap a spare tube there (which keeps the right tube on the right bike). The tube is in a bag but the bag tends to snag and rip, and dirt/grit gets in. It also doesn't look very nice.  I should be able to make much better use of this space, to hold more than just a tube, and hold it better

I don't believe there's a product on the market, so I think I'd like to repurpose/make something.  It should be secure against falling off, and keep the dirt and the worst of the water out.

I've found this winter that on long rides (200km+, essentially unsupported but with occasional food stops) the bike is fully loaded. I don't really  want to fit the rack/panniers (weight and drag) when I'm already pushing myself quite hard, and can't add a handlebar bag because of my lights.

I've already got a top-tube bag (snacks/gels, backup battery for phone/lights), saddlebag (first aid kit, foil blanket, more snacks/gels, spare tube, jacket and shoe covers strapped underneath if not on me), 2 water bottles, tool case in 3rd bottle cage, jersey pockets full (2nd breakfast/litter, money/cards, any extra warm layers)

Good question - I've wondered the same.

I looked at the Specialized SWAT toolbox for inspiration, but it only fit certain models of frame.
https://www.specialized.com/us/en/equipment/bike-accessories/swat-technology/c/swatstorage

Another option is to mount things directly to the waterbottle cage mounts.  Here's another specialized product to do exactly that:

https://www.specialized.com/us/en/emt-cage-mount-mtb-tool-for-right-zee-cage/p/132369

Downsides of this is that it only fits their multitool and nothing else.  Also exposes the tool to a lot of dirt and muck that it wouldn't see if higher up.

I have tried a solution of using a frame mount bag right at the front of the main triangle.   Advantages are that its forward weight so helps me keep the front wheel down on a steel climb, and I can put a USB battery in here for powering my gopro on long rides.

Alright this bag was measured for another bike so its a bit saggy here.  The pump hook gets in the way, and the downtube is much smaller and a different angle from the designed bike.  Flaws - the zip is the wrong way around, and should close forward so cables can come out easier.  Velcro is all wrong for this bike.

I also use a top-tube bag for more storage when on a long ride.   That holds snacks and my phone running on another USB battery (because its annoying when strava stops recording.)


Tire Size For Schawla 220 What tire size will fit a Schwala Xero 220 rim?  Can it take any 700C tire?

I am having trouble figuring out what size tires could possibly fit this rim: http://www.formulahubs.com/en/xero/?method=detail&aid=17.  The closest I see is this rim size: 700C*20*19MM.

You won't be able to use ANY 700C tire, but you should be able to use anything between 700Cx19 to 700Cx25.

Sheldon Browns site has a ton of information on tire sizing. In general he recommends 1.45 to 2.0 times the inner rim width.  In your case this appears to be 13mm.

http://sheldonbrown.com/tire-sizing.html


In practical terms, how often do you have to adjust the belt tension of a belt drive bicycle? Gates claims their belts do not stretch over their life, so theoretically speaking you should not have to adjust the tension (which appears finicky).

I'm interested in anyone with real world experience. Do you ever have to adjust the tension of the belt, apart from when you have to move the back wheel for another reason, such as to change a tyre?

Gates, who make the belts have a FAQ. I can't get a direct link, but if you go to http://www.carbondrivesystems.com/support.php under the question "What are the benefits to the Carbon Drive systems?" this is part of their answer.

  No Stretch – The Carbon Drive belt does not stretch over time like a chain. This means you don’t have to re-tension the belt, or replace the belt due to stretch. This also means no excessive wear on pulleys due to stretch.

Does this claim hold up in practice?

I have been riding a Gates CDC (not Centertrack) belt drive for almost a year now.  Gates claims that tension adjustments are not necessary over the lifetime of the belt drive.  My experience does not support this claim.

One of Gates' claims is that the belt does not stretch enough to warrant tension adjustment after a break-in period, as you would on a brake or shifter cable.  I found this to be true.

However, I have noticed that the tension of the belt changes significantly with temperature (and possibly humidity, though I don't have enough data to test that hypothesis).  I have ridden my bike in various weather conditions and temperatures ranging from over 90℉/32°C to under 0℉/-17°C. I use the Gates iPhone app to check my belt's tension.  I have noticed that, if the belt is tensioned properly at about room temperature, then the tension in the belt decreases below the recommended tension range when the ambient temperature drops below about 20℉/-6°C.  I have noticed problems with the belt drive when tension is too high or too low, including excessive noise, skipping, and misalignment leading to dropping the belt from the sprockets.  Therefore, I found it necessary to retension the belt slightly in the beginning of the winter and again at the end of winter.

I'm not certain yet if the weather-related change in tension is caused by frame shrinkage (I suspect this is the case - my frame is aluminium) or by another factor.


What are some good exercises to prevent knee pain? About four or so years ago, I hurt my knee on a fairly long ride (~150km or so).  It was really my own fault, as I hadn't been training regularly, and I pushed myself a bit too hard.  By the time I arrived home, my left knee had swollen up and was in quite a bit of pain.  I stopped riding for about a half year, and when I started up again I took things lightly and tried to train more regularly.

Fast-forward to today.  I am riding 20km per day, and am spinning at high cadence when I ride.  I try to stretch both my knees before/after riding, but I still feel some soreness or pain when I ride.  Although I haven't yet experienced anything as bad as the original injury, I'm worried that if I will get injured on the next long-distance ride that I take.

What are some good exercises that I can do to prevent re-injuring my knees during future rides?  Are there any particular stretches which are helpful in loosening up the knee before riding?

The problem with diagnosing knee pain is there are multiple possible causes. The original cause may not even be in the knee itself! I have a cyclist friend whose knee seized up. He went to a physiotherapist, who explained that the real problem was an extremely tight lower back. The tightening back was tugging at his gluteal muscle (buttock), which in turn was tightening his hamstring - which was pulling his knee out of alignment! His body was actually acting against itself, as each muscle struggled to retain its preferred position. The physio pummelled out his back and glutes, he did back stretches for a few weeks, and everything relaxed.

I've had ITBS for almost a year, caused by a combination of incorrect seat height and an over-aggressive cycling schedule. The iliotibial band is a tendon-like bit of muscle which runs down the outside of the thigh and connects the hip and knee. When it tightens, it pulls at your knee-joint and rubs painfully against the bone, becoming inflamed.

For this problem, stretching has been surprisingly effective. I stretch the IT band itself, my hamstrings, and my lower back and glutes. The stretches I do are:

IT band - Standing stretch. Stand upright and cross one foot behind the other. Then lean towards the foot that is behind the other. Hold this stretch for about 15 to 20 seconds, and then repeat it 3 to 4 times on each leg.

Hamstring - Standing stretch. Basically, try and touch your toes, although I do this with legs crossed one behind the other. With this one, if you let your upper body just hang loose, you will feel the stretch increase naturally after a few seconds.

Glutes/lower back - Seated twist. This is an effective stretch for the big muscles in your buttocks.

Glutes/lower back - Supine spinal twist. Great for the lower back, and your hips.

Obviously, these exercises may or may not be helpful for you, depending on the exact cause of your problem. Only a doctor will be able to correctly diagnose your issue. But they're easy to do, safe, free, and may be helpful.


Why so few mountain bikers with spandex? I've never had clothing that was specialized for cycling, so I'm kinda n00b in that area.

I am confused about the use of spandex.

It's very common among roadies, for obvious reasons. It's more comfortable, has less friction on the seat, and is more aerodynamic.

Why doesn't it make sense for mountain bikers? You do see plenty of XC riders with spandex, but not in "120-160mm travel" areas like trail/enduro. Those guys seem to use basic shorts of one type or another, that catch air and might catch on branches.

Why isn't spandex just as common in the mtb circles? Is it a cultural thing?

As already said, aerodynamics are less important to MTB's, but otherwise its largely convention and fashion that dictate what people wear.

A vast majority of MTB'r are not wearing basic shorts - they are usually wearing shorts made for riding, including padding just like Lycra road shorts, flat seams and materials designed to withstand the rigour of riding. Many MTB shorts consist of removable lycra under shorts with the baggy outer designed for cycling.

For me personally, I wear baggies MTBing because we often spend time "in public" - around cafes or pubs after the ride, socialising and I feel like a fashion mistake (and I am not fashion concious) walking into a cafe in lycra. I will wear lycra if doing long distances, or I know I won't be more than 10 feet from the bike for the whole time I am out, but feel more comfortable wearing shorts.


Is it safe to leave my carbon bike in my stationary trainer for extended periods of time? This time of year, I leave my race (carbon) bike on the trainer and when nice enough, just ride my rain/wet/commuter/cx bike.

I do replace the 'race' skewer with a steel skewer for trainer use.

Will it damage the carbon if I leave the bicycle clamped and ready to train on the trainer? Should I release the clamp every time I'm done training?

If this is the kind you have, then leaving the bike in there should make no difference whatsoever. This trainer clamps onto the rear axle, it doesn't even touch the frame. When you're off the bike, the frame doesn't have to do anything except support its own weight - there's no possible way it could get damaged.

You're probably less likely to damage the bike, since you won't be knocking it over.


can i use a 700c tire (Gatorskin 700c x23) on a 650 wheel I am thinking of getting some Velocity Rims that are 650c but I am wondering if I will be able to use my 700x23c Gatorskin tires on them? Also what do you think about 650c wheels pros and cons.

Also, lets say I just buy the 650 rims do I need to change anything else in the bike? I have a Fuji Newest 3.0, I think the 2008 version, if that helps.

No you will not be able to use your 700x23c tire on a 650c rim. The bead seat diameter of 700c rims is 622mm, this will also be the bead diameter of the your 700x23c tire.  The bead seat diameter of a 650c rim is 571mm (see Velocity's Spec section). Your 700x23c tire will be 51mm too wide.


Compact crankset, how to use and criticality of cross chaining I have a road bike with 50/34 compact crankset and 12/27 10sp cassette.

While I don't think I could run a 53/39 one given the hills I happen to climb, but sometimes I get the feeling the right gears are precisely close to the cross chaining limit.

I get the feeling when riding on the 34 that it is always too easy unless I ride on the 12/13/14t cogs, or when on the 50, that it is too hard unless I get on the 21t cog...

I mean, when on the flat, I feel better on the 50 as I could get faster spots when smaller cogs will definitely be better, but when riding at ~25kph, it just feels like I am all the time "in between"...

Any tips?

Also, given that the crankset only has two rings, is the cross-chaining less of an issue than on a triple?

A 53 x 39 won't really make things better for you as you'll be even more cross geared in your 53. That said, riding a 50 x 21 on your 12-27 cassette can't really be considered cross gearing.

If you'd like less of a jump in ratios when shifting the front chain ring, might I suggest a cyclocross crankset? Shimano's cx50 and cx70 offer a 46x36 up front. They'll let you ride more in the middle of your cassette on the 46 and still give you a decent low ratio. You do lose a little top end but few people are exceeding 50kph for any length of time.

I have a cyclocross bike with a 46x36 and a 12x27 and find it fully useable for the speeds I pedal at and shifting the front doesn't result in 3 gear changes in the rear.

Here's a link to the Shimano cross cranksets: http://www.shimano.com/publish/content/global_cycle/en/us/index/products/cyclocross/cx70.html