Does a crank arm Power Meter measure power in both directions? The leg on the upstroke weighs down on the pedal and creates additional work for the leg on the downstroke. A crank/hub power meter ignores that and gives you the effective power combined by both legs.

Lets assume a rider generates 120W on the downstroke and -20W on the backstroke. Total power would be 100W.

Now can the crank arm measure the negative power on the backstroke and substract it?

(If, as I've learned, it can not differenciate between positive and negative power a crank arm power meter would show 140W. If it can only measure one side you get 120W)

Some power meters measure forces or torque on a drivetrain component located downstream of the bottom bracket and hence can only provide data on the net forces (or torque) applied to both crank arms combined. These power meters are unable to distinguish between how those net forces (or torque) are generated by each leg at each point of rotation of the crank arms.

Examples of such power meters include devices taking strain measurements at the crank spider, the chainring, the chain, the cog(s), the hub, or even at the rear tyre when the bicycle is on a power measurement ergometer. SRM, Power2Max, Quarq, Powertap hubs and C1 chainrings all fall into this category of power meter. Ergometers such as the Wattbike also fall into this category as they measure strain at an internal component driven by the chain.

However there are other power meters that measure the forces (or torque) upstream of the bottom bracket, e.g. measure the forces (or torque) on each crank arm or on each pedal independently (there are even meters proposed to measure the forces at the shoe cleat). These meters do the calculations and provide the same net power data that the other type of power meters do. Such meters include Garmin Vector pedals, Powertap P1 pedals, Infocrank and Pioneer. But they have the capability to provide the extra data generated by measuring the forces applied by each leg independently.

To provide the extra data from each crank arm (or pedal) it requires appropriate software and a bicycle computer head unit with the capability to record and provide this additional data.

For the most part, such meters don't readily provide this extra data, but rather provide down-sampled subsets, such as a left/right power balance. This is because the common communication standards in use for many bicycle handlebar computers (i.e. ANT+) as yet don't have this capability. So in order to provide such data it generally requires proprietary data capture hardware and software.

The question still remains as to the utility of this extra data and whether it provides any actionable intelligence.

In terms of the propelling the bicycle forward, all that matters are the net forces and the velocity at which those net forces are applied and so whether a power meter is measuring up or downstream of the bottom bracket matters little.

Where examining the independent crank (or pedal) data may be of some use is in analysing pedalling "techniques". This is not new in terms of the science of bicycling biomechanics, there have been such devices used in labs for many decades with research dating back to the late 1960s (e.g. Hoes et al). Independent crank force measurements were first reported in the literature in the 1890s! Since paper(s) by Hoes et al then there has been research into crank forces by Coyle et al, Korff, Edwards, J. Martin and no doubt many others.

One interesting aspect of the research is that while there is much made of "pedalling technique", the reality is that how we end up pedalling naturally is pretty darn hard to beat. Another is that just because there may be some negative torque on the upswinging crank arm, that does not mean it is a bad thing. Indeed if you look at data by Coyle and Korff, it's pretty normal for many elite professional level road riders.

Here is an image extracted from the Coyle et al study which does indeed show riders often apply some negative torque at some points around the pedal stroke:


Can Tacx Flow head unit work with old (2002) Basic frame/brake? I want to replace a lost head unit/computer on my old Tacx Basic from 2002, does anybody know if modern Flow head unit will work with this old frame/load generator? I think such was an upgrade path, once, but still - the frame is really old (but in good working condition).

As suggested in a comment on the question, the load generator for the Tacx Basic in the early 2000's was the same load generator used across the entire Tacx ergometer line. The Basic, the Grand Excel, the Flow, and the I-Magic all used the same load generator, so the head units are interchangeable. The capabilities of the Basic can thus be "upgraded" by switching to a Grand Excel or I-Magic head unit (the Flow replaced the Basic in the Tacx line in 2004 or 2005 and, except for a larger screen and slightly easier calibration procedure the models are equivalent).


Is there a way to remove the dent/bend? I have a 2005 KHS Flite, which I am fairly sure is a Reynolds 520 frame, that I absolutely love and have morphed through many variations (the original brakeless fixie, then both breaks free-wheel, then upright gentleman's bike that can still whip, and so on).  Someone tried to steel it or just decided to fuck with it, and bent the downtube/put a dent in the downtube.  It's not major enough to keep me from riding it -  at least I don't think it should, I could be wrong. I was wondering if there is anyway to work out the dent.  Maybe from the inside out somehow?  It's thumb print size into the metal, with little to no warping around the indentation.

Since you didn't put a picture, I'm going to guess it is not significantly dented enough to worry about it (in which case, I'd just leave it alone since anything else will be uglier), but you should take it to a bike shop to get a professional opinion (so everything here is obviously all at you're own risk).

One way is the ShelBroCo Dent Removal System (joke). A more serious overview from Sheldon Brown's site is here.

For seat tubes and head tubes, you can try from the inside to press the dent out but I don't see you you could do it on the downtube.

Frame blocks (made by companies like Bicycle Research, though you could make your own if you have access to a machine shop quite easily) are one solution. They're essentially 2 machined pieces of metal which you clamp over the tube and rotate the frame to try to push the tube back into shape. An example is here. Note that this will strip the paint off that area as well.

Bondo is another solution.

The extreme solution is to replace the tube (or part of it).


Threaded bleed port - 105 7020 shifter In attempting to bleed my Shimano 105 hydraulic disc brakes, I seem to have threaded the bleed port so the screw no longer tightens. Screw is fine in the other shifter, and same issue when using screw from other shifter.
I (foolishly) used a metal aftermarket bleed cup adapter and I think over-tightening has caused the issue!
Any ideas how to remedy, without needing to buy a new shifter?
In attached pic, screw is #4 and offending adapter is #12.

Furlough means I don't have one in front of me, but if memory serves the piece with the threads is separate from the main body of the lever, even though Shimano doesn't make it available individually. I believe it's like a reservoir cap and there's a hidden gasket or rubber diaphragm in between it and the lever body, and it's held on by some screws. If that's all true then I think your best shot at a fix is finding another of the same lever that died from other causes and cannibalizing the part. The upshot here is that the 7000 series 105 levers have actually had some QC type issues with the shifter getting jammed early in its life. I'm not saying it's a common issue per se but I've seen 3 of them I handled myself and can remember since these have been out, both the mechanical ST-R7000 and your ST-R7020. Shimano sends warranty units and has shops send the dead ones back. I think there's a fair bit of this going around so there may be some chance for you to find one to swap with. Some might be going in the trash too.

I'm a little torn on whether helicoiling seems like a good idea here because of the risk of it not being able to contain the oil pressure. That o-ring is there for a reason. There are other applications where helical inserts contain all sorts of pressure, like engines, but the bolts are bigger and can be torqued higher there and will presumably form a much tighter seal. So I don't think it's probably a great idea but if you're willing to take on some risk it might work.


Trek 6500 rear derailleur I am rebuilding a Trek Mountain Bike model 6500 built in 2005.  I don't see a model number on the Shimano Deore rear 8 speed derailleur that needs replacing.  Is there a hidden model number somewhere on the unit, or do I just need to replace it with a standard Shimano Deore unit?  How do I know what to order?

If you are looking for an exact replacement the part # will be stamped on the inside (wheel side) of the parallelogram linkage. This is the middle section of the derailleur it is the part between the mounting or "B" knuckle and the jockey wheel cage. The numbers will be small and are read more easily with the derailleur off the bike. It should begin with RD followed by four digits or RD M followed by three digits. You will also want to measure the distance between the jockey wheel mounting bolts to get the correct cage length as this will effect tooth/gear capacity.


Can I put a 700 x 35 tire on a Cannondale Quick 2 that has a 700 x 28 tire? I usually ride roads with my 700 x 28 tire, but want to do a trail that has a multitude of surfaces.  So can I put a 700 x 35 on this bike?

Unfortunately manufacturers tend not to publish max tire sizes, and ties of nominally the same width can vary quite a bit in actual width.

Checking the Cannondale web site shows that the Quick 2 model comes with nominally 30mm tires as standard. You can probably go up to 32mm with no problems but there may not be clearance for 35mm.

The place with the least tire clearance is typically between the chainstays. Measure the installed width of your 28mm tires and see of there is an additional 2.5 or 3.5 mm or clearance between the tires and frame.

You can also consider running a lower tire pressure on poor surfaces for better comfort and traction.


Extend drop bars with additional positions I have my touring bike set up with drop bars, very similar to this:

However, after riding all day for a few days, I tend to miss additional position(s) to avoid minor annoyances such as "numb fingers" and sore back and neck

I tend to never use the drop bar racing position, but stick to the position where you hold top of the brakes and the position where you hold the straight part of the bar.

What I miss is an alternative (and probably more upright) position. Triathlon aero-bars is an obvious suggestion for additional positions, but not really what I'm looking for.

Therefore: what are creative ideas on how to add additional positions to a drop bar?

Sheldon Brown has a page about adding a second set of handlebars above your first set. It looks terrible:

Why not give that a shot? Sounds like it will fulfil your desires.


What's the best way to remove stick-on frame protectors I need to move a couple of frame protectors from the head tube of my bike but don't want to damage the paint in removing them. What's the best way of getting these off?

It depends on the type of adhesive. Sometimes it can be just pulled off. Sometimes the gentle heat of a hairdryer (not a heat gun) can weaken an adhesive and make it easier to remove.

Or you can try the use of GooGone or similar adhesive thinner/solvent (try on an inconspicuous place first to make sure it won't damage the finish).

Heat and solvent cover 90% of cases.

If the protector was epoxied on, then it is very hard to take off without damaging the finish.


Freehub has started slipping, what can I do? I've just gone through the london winter and both my bikes now have a slipping freehub. Admittedly my mountain bikes' freehub is quite old and probably worn out, but I'm wondering if they are seized up inside and I can apply some lubrication to stop it from slipping? Anyone got any good advice?

It can happen that the pawls get sticky and cleaning helps. Here's a couple of guides:

http://www.parktool.com/blog/repair-help/freehub-service
http://www.bikeradar.com/gear/article/workshop-how-to-overhaul-your-freehub-23757/

Cold also makes it worse, but this covers much worse temperatures that the UK:
http://www.icebike.org/Equipment/freehub.htm

(And while it's true that "flushing with solvent has not been a reliable substitute for full disassembly", if the freewheel isn't engaging at all, just drenching it with WD-40 can work as a short term fix until you get round to a proper job.)


Road Tire Performance in Rain and Snow How well do road tires perform in rain and the snow? I've heard narrow tires are better because they actually can put more weight/pressure on the road through the wet/ice.

I just bought Continental Gatorskin tires, live in Boston, and just want to know what I should be thinking about in adverse weather conditions.

Relevant info:

Riding Cyclocross bike ~35-45 mi/week with 10 mi (roundtrip) commute. Occasional 30-40 weekend jaunts, and am coming from much more threaded cyclocross tires (I never rode off-road much).

Slick tires, like your conti's, have no problem in wet conditions. If the streets you ride in Boston in winter are just wet with occasional light slush you're fine with what you got.

You'll want knobby tires if you're regularly riding in something soft like dirt, mud, packed snow or very heavy slush. Slick tires are significantly more squirrely in those conditions. In that case, typical cross tires will be better.


Is it ok to sit on the top tube of my Cannondale CAAD12 (2017 model)? I just picked up my new Cannondale CAAD12 bike the other day. During my first ride I occasionally was sitting on the top tube (waiting for traffic lights etc). After the ride was over I actually realised this might be bad for the frame and I started to worry, especially because the CAAD12 frames are so light considering they are made from aluminium. Any ideas if sitting on the top tube of a lightweight alu bike like the CAAD12 is a no-no? I inspected the frame and it seems ok though, but I am not an expert. My weight is around 170 lbs.

If sitting on your top tube causes damage to your bike, the bike wasn't very safe to begin with. I imagine while sitting you have at least one foot on the ground, so your entire mass is not resting on the tube.

The amount of force that a frame must withstand is much greater than the weight of the rider. If simply placing 170 lbs as a static load was enough to damage your frame, there would be no way to safely ride the bike.

Update: While not the most scientific test, I decided to try a worst case top tube sitting scenario. I went for a 5 mile ride last night on my alloy road bike. While not as high speed, low drag as the OP's rig, it is all I have. I, a rather large 6'2" 210lbs rider, sat on my top tube while riding for as much of my ride as possible. I do not recommend this, as it turned out to be very painful, and I got some looks form other riders for some reason. Most of the ride was on roads that are not in the best condition (holes, cracks, gravel). Again, I do not recommend this. After completing my 5 miles on the top tube, I brought my frame to work for some x-rays. I x-rayed the entire main triangle, as well as the welds to the rear triangle. I can report that there was no signs of any damage (cracking or deformation of the alloy). There was a bit of damage to me however, as apparently it is a bad idea to sit on the top tube while moving.

Update 2: the mechanical engineers I work with and I conducted an experiment. We got some aluminum alloy tubes (approx 1.25mm wall thickness). It as standard 6061, which is not exactly what is used in the OP's bike. We welded up a main triangle as close to the geometry of the OP's bike as we could. We have learned a few things from this:

None of us should quit our day jobs to build bike frames. Man is that hard.
The strength of the main triangle is insane, assuming the forces are perpendicular to any side. We were about to load a static load of over 350lbs on the "top tube" before it buckled.
Bike frames are not designed to handle rotational forces. The frame will twist up with relatively low force (a torque of about 200lbft.) This force was exerted at what would be the head tube.
Science is great.

In conclusion, go ahead and sit on your top tube at lights. Since I read this post I have started doing it and it can be quite comfortable.


How to determine the minimum tire pressure if the manufacturer does not? Some tires only have the maximum pressure written on them, stating nothing about the minimum. For soft and comfortable rides, the recommendation is to inflate them to lower pressures, but then how to avoid under-inflation? Should we just not overthink it and stick to a reasonable value, such as 80% of the maximum pressure? (That's what I would estimate based on a few pressure charts I have seen.)

Smaller tires need to be run at higher pressures to accommodate the same weight. You want to have enough air that the tire's rolling resistance is good but you don't get pinch flats / damage from appropriate road hazards. Too little/much air can affect control to some extent as well. If you have tubeless tires, you can usually run lower pressures (since there is no tube to pinch flat); your rims may or may not be setup for this.
If the tire isn't deflecting, the tire is overinflated. You should see some (but not a huge) amount of deflection when the tire is loaded. Here are some pictures from Schwalbe:

I'd start with some guide like this one from Schwalbe as a guideline (interpolate/extrapolate for your body weight/tire size, and move up / down if it seems over/under inflated)

Tire Width
Body Weight

130 lbs (59 kg)
185 lbs (83 kg)
240 lbs (109 kg)

25 mm
85 psi
100 psi
115 psi

28 mm
80 psi
95 psi
110 psi

32 mm
65 psi
80 psi
95 psi

37 mm
55 psi
70 psi
80 psi

40 mm
50 psi
65 psi
80 psi

47 mm
45 psi
55 psi
70 psi

50 mm
35 psi
55 psi
70 psi

55 mm
30 psi
45 psi
55 psi

60 mm
30 psi
45 psi
55 psi

80% of the sidewall pressure may be too high/low for you; it depends on how heavy you are and what that manufacturer put on the sidewall. However, once you pump up your tires a few times and get a feeling for what tire pressures work for you for your tire sizes, you won't really worry and will have a natural feel for it.


Shimano gear cable adjuster barrel replacement I have a hybrid-style bike with Shimano parts and I'd like to replace the gear cable "adjuster barrel" (?) on the shifter next to my front left brake, as I have mangled it by twisting it with a pair of pliers.

However, I'm not sure exactly what part I need to buy. This looks similar: http://www.halfords.com/cycling/parts/gears-drivetrain-cables/shimano-rd-7700-cable-adjuster-bolt-unit#tab3 ...but it says that it's for the rear derailleur rather than a front shifter, so I'm not sure if it's the right part. If not, could anyone tell me exactly which part I'd need to buy?

Thanks.

They are same. But before spending money in it, it can be wise to check the threads in the shifter. If pliers used to twist it, the threads could deform, and new barrel will act the same.


What's difference between 1/2 and 9/16 inch pedals? I've this bike MTB hardtail Marin Bolinas Ridge 2012.

And it has generic composite pedals which I want to change.

So while choosing pedals I saw two different choices, 1/2 and 9/16 inch pedals.

I didn't understand what does this sizes mean and apply to what.

Please if someone can explain it to me.

For example: Diamondback Sound Pedal 9/16 and 1/2 model

The measurement is for the diameter of the pedal spindles, where they thread into the cranks. You need to find out whether your existing pedals' axle is 9/16" or 1/2". If there is no measurement indication on your existing pedals or the paperwork which came with your bike, ask your LBS if they could test out with some existing pedals to find out what size you need.


What to do about hypothermia on a long ride? Recently, I had a long ride in winter, about 100km (62 miles) and was about 5-8 degree c (41-46F). I was wearing a windstopper jacket and basic cycling pants.

At later stage of the ride I felt legs aren't producing enough pedaling force and muscles feel quite painful and sore. And eventually I am home. Even though it was pretty warm, I still felt myself not producing any heat. I even tried putting myself into a hot shower and I was still shaking... And then I started to eat a lot. And It still didn't stop me from shaking...

And I then went to bed with electrical warming blankets and started to recover.

My question is, what are the symptoms and what should you do to avoid hypothermia in a winter ride. What if you are already suffering from hypothermia?

Hypothermia can sneak up on a person.  Unless you're paying attention, you usually won't notice until you're extremely cold.  Hypothermia can slow your reaction times and cause severe lapses in judgement, so be very careful out there!  It's best to avoid it altogether, but if it happens, don't trust yourself to make good decisions.

As far as what to wear:  I'm kind of a gearhead, so I like to wear fancy softshell clothing.  It's great stuff because it breathes well and lets out moisture but still blocks wind and (mostly) blocks rain.  If you're into that sort of thing, Pearl Izumi and Castelli both make some great gear.  If you're on a bit of a budget, I'd lean toward the tried and true wool.  Avoid cotton like the plague -- when it gets wet, cotton will make you extremely cold.

We lose a lot of heat through our heads, so in the cold months it's important to have a hat on under your helmet.  I have a thin wool hat that keeps my head warm and fits nicely under my helmet.  Be sure to wear a warm layer and a wind blocking layer.  Wearing a wool sweater and a windproof jacket over the top will often be enough.

Gloves can also be very important -- when I'm riding long distances in the winter months, I find gloves help me keep my fingers nimble.  Making sure your fingers are warm enough to work well can be a serious safety concern when it comes to braking.

Most of all, be aware of how you feel.  If you feel cold and then later your hands are stiff but you don't feel cold any more, that's a warning sign.

As far as warming up goes, you did quite well.  I would add a warm beverage to the mix -- hot tea, hot chocolate, or whatever you prefer -- as it helps warm you from within.


What are the main improvements with road bikes in the last 23 years that the rider would notice? Back when I was a younger man I bought a road bike, a 1998 Giant Kronos.  It has a frame made from aluminum tubes, a triple chainring in front, and a 7-sprocket cassette in back.  By US standards, it was an entry-level quality road bike from a bike shop.  I rode the bike solo for about five years, and then moved to a different area and hung the bike up on hooks for nearly a decade.  I started riding it again, got hooked again, and this time I discovered group rides.  I've been having lots of fun, and I met some great friends.  I upgraded the bike's saddle, brakes, and pedals.  IIRC the bike weighs about 26 lbs / 12 kg with the frame pump, saddle bag and tools, and a full water bottle.
My friends have been gently urging me to consider buying a new road bike with an aluminum frame, or a more recent used one.  Maybe I could afford a used bike with a carbon-fiber frame.  My bike did stand out in group rides back in the pre-pandemic days, typically being the only one with a horizontal top tube, a triple front chainring, and a quill stem.  Now that I'm middle-aged I don't mind if my bike looks old-fashioned.  But I am slow, always in the group at the back of the group rides, and my main riding buddy has to wait a few seconds at the top of hills for me, so anything that makes me faster would be welcome.
So what's changed in road bikes in the last 23 years, broadly?  My friends say that bikes have improved tremendously since 1998.  I know they're lighter, but I could weigh any bike I was thinking of buying and see exactly how much lighter it is compared to my existing bike, so please don't focus only on weight.  What improvements would I notice in the saddle of a newer bike, besides just being lighter and faster?

I coincidentally bought an aluminum road bike (Cannondale) about the same time as you got your Giant and with very similar specs. Mine was 3x8 rather than 3x7, but same size chainrings and similar gear range. I rode it until the frame was cracked in an unfortunate incident and replaced it with a relatively modern Felt aluminum bike with 2x10 gearing with a compact double chainring. I actually still use the 3x8 drivetrain components on a commuter bike.
On the plus side, by 1998, many of the really substantive changes in road bike technology had already happened. Combined brake lever/shifters were standard, as well as dual pivot brake calipers, which have a lot better stopping power than some of the earlier single-pivot side pull calipers.
So what's changed?
Brakes
Although disc brakes are not yet standard technology for road bikes, the trend is certainly in that direction. Disc brakes are not something that can be retrofit on an old frame, so if you want those, you do need to get a newer bike.
The primary advantage of discs in better stopping power in rain and overall slightly more consistent performance. That said, the dual pivot caliper rim brakes that you have now have great stopping power as long as the pads are kept in good condition. The only reason I can imagine switching to discs is if you ride a lot in a group with other riders who have discs and you ride in the rain. In wet conditions, those other riders might stop more quickly than you can with your rim brakes and cause a crash. Or if you ride a lot on dirt roads, disc brakes have the advantage of not being affected if your rim gets muddy going through a puddle.
Wheels/tires
Another major trend in the last 20 years is a shift towards wider tires with lower air pressures, even among pro racers. Whereas most road bikes were equipped with 23mm wide tires or even narrower in 1999, now 25 and 28 mm are very common and many bikes have even wider tires. The high quality wide tires have no greater rolling resistance than the narrow ones, and the lower pressure makes the ride much smoother.
Because narrow tires were standard in the 90's, many frames did not have clearance for anything larger than 25, so if you wanted to try wider tires, you might be limited. You'd have to measure your frame to check. And if you're happy with the narrow tires you're on now, it doesn't matter.
Frame design
As you noted, a big change since 1999 is the ubiquity of sloping top tubes. Frame construction has also changed a bit, so a comparable aluminum frame today would likely be a bit lighter than your current one and feel a bit less stiff, though road feel is generally much more dependent on tire construction and pressure than on frame materials. But unless there's something you don't like about your current frame, I doubt it's worth the investment to replace it just because the newer ones look different.
Drive Train
Better chainring design (ramps and pins) has enabled double chainrings with large differences in size, and the number of cogs in the rear continues to increase (now 11 is standard on expensive bikes). As a result triple chainrings have largely disappeared from even the lower tiers of expensive road bikes. The main benefit of the doubles over triples is weight, though. There isn't a big difference in performance. And counterintuitively, you may find yourself shifting between chainrings more frequently on the double than you did on the triple because the switch point is in the middle range where you ride most. On the triple, I find that I ride a lot on the middle ring and mainly only use the big when descending and the small when climbing.
If you find your current gearing is a bit high for you, you can easily switch to smaller chainrings on the current setup. I've run 26/39/50 on those same Shimano triple cranks that you have that came with 30/42/52 originally. You should still be able to buy 39 and 50t chainrings with ramps and pins to work together properly, since Shimano sold Tiagra and Sora groupsets with 28/39/50 triples using the same BCD as the 30/42/52.
A downside to the new drivetrains is that the narrow cogs and chains wear much more quickly than the thicker ones in a 7-speed set up (and are more expensive to replace).
New cranks are also lighter due to the switch from square taper spindles to hollow spindles and external bearings. If weight isn't a concern for you, there's really no advantage.
And of course, if you want to switch to a 2x11 drive train, all of the components can be put on your existing frame, so you can upgrade without changing the frame.
Conclusion
If weight is not a concern, the primary benefit to a new bike would be the ability to have disc brakes, which aren't even standard on road bikes now.
You might find that wider lower pressure tires and lower gears make your riding more enjoyable, especially now that you're 20 years older than when you bought the Giant. But if you're comfortable on long rides the way it is, there's no need to change just to follow the trends.
If you want to cut a bit of weight, you can do it by upgrading parts. Perhaps look at nicer wheels or switch to a hollow spindle crank and external bearing BB such as the Tiagra triple from the 3x9 speed era, which would be compatible with all your existing equipment. Just swap on your current chainrings and you're good to go.


Correct position of hands on flat handlebars I have had a numbing sensation in my thumbs. I take it it is caused by the pressure of holding the handlebars while riding. The bike is a Schwinn Signature M3030 - SR SUNTOUR mountain bike.

Could be the position of yours hands, which you can adjust yourself, but is more likely a combination of the over all bike fit. Things such as seat position, handlebar height and a variety of other things all play a part in how much pressure your hands exert onto the handlebars. Riding a bike that is too large can have your body leaning to much on the bars and exerting too much force on your hands and wrists.

Depending on what grip you currently use you might try changing them to something a bit softer such as some of the silicone variety, ESI or similar for example. Sometime gel padded gloves can help but I would venture to guess that it is a bit more complex and probably related to the over all fit of the bike.

If you ride often numbness is definitely something you should take seriously and if it is worth the money and you do ride often, you may think about having a proper fit done at a shop or at very least take your bike in and explain the problem and get their opinion.

Also, make sure you are not gripping the bike too hard, sounds silly but it is possible, your grip should be firm but semi relaxed, not holding on for dear life sort of grip.

Lastly, the angle of your wrists can also be a factor, depending on what type of shifters/brake lever you have you might try adjusting them downward or upward to try and find a more comfortable and natural position.


Get a tougher gear on Shimano GRX, 11-34T, 2x11 I have a new 2021 Cube Nuroad Race gravel bike with Shimano GRX, 11-34T, 2x11.
I am used to riding a road bike, and find on the new one I don't need the easiest gears on the hills, but could use a tougher gear on the downhill as I can't get any power down when descending. (I have switched the 40mm tyres for 32mm tyres while the weather is still not half bad in the UK).
I have never messed about with the cassette on a bike, switching gears etc, and was wondering how to go about it. Do I need to buy a whole new cassette? What cassettes are suitable and compatible?
Thanks
Edit:
Some useful suggestions. For more information, it is not just pedalling down serious slopes that I run out of gears, but on not very steep descents and occasionally on the flat if my speed is up. Though it seems what I need is to switch out the chain rings.

You cannot get a higher gear ratio by replacing the cassette. The 11 tooth sprocket is the smallest you can get on a compatible cassette. (Systems with 10 tooth sprockets exist but use a different freehub design).
The issue is that you have 46/30 tooth sub-compact chainrings (I looked up specs here). Which are giving you the low ratios. This is common on gravel bikes as they have larger diameter tires run at lower pressures and are designed to negotiate rougher surfaces. A road bike typically has 50/34 or 52/36 tooth chainrings.
If you want higher gear ratios you have to get larger chainrings. GRX 2x11 cranks only come in the 46/30 size. You may be able to find larger rings made by another manufacturer that fit the GRX crank, or you get a whole replacement crank with larger rings.
If you still want to know how cassettes fit on hubs see this Park Tool video. There are a few standards for the freehub that the cassette fits on. Shimano's HyperGlide II is dominant and also used by SRAM. Campagnolo has their own standard. Systems that permit 10 tooth sprockets like SRAM XD and XDR are becoming more popular. In addition to the freehub attachment the cassette sprocket tooth range has to fit inside what the rear derailleur can handle. This includes the max sprocket size and 'total capacity' (difference between chainring tooth counts plus difference between largest and smallest sprocket tooth counts).


What's the best way for a beginner cyclist to carry children? My sister has two children, aged 4 and 2. The 4 year old is starting to get confident on his bike and my sister is finding she can't keep up with him on foot any more. She hasn't ridden since she was a kid and so isn't very confident on a bike. She will only be riding on sealed bike trails (not on road) for the foreseeable future.

I'm not convinced any of the "on bike seat" style of child carriers will work very well for her, because of the reduction in stability and her lack of practice/confidence.

I suggested a trailer but she was wary of the extra weight and the effort required going up hills. I still think this is the best option though.

The other alternatives, the bigger trikes with seating built in are possibly a bit too expensive.

So my question is what's the best compromise of safety, cost, stability, weight and convenience for transporting kids?

The best option is a trailer. The pull weight is fairly low, and the safety factor is far greater than on a child seat.

To summarize what is a very long discussion, the child in a seat can't protect themselves, should you crash, and there is no way for you to protect them by guaranteeing you don't crash.

A trailer has a lower center of gravity, a more stable structure, protection from sun and rain, and a more comfortable ride. It will be heavier to pull uphill, but on sealed bike paths, that is not typically a major issue.

See this question for more information.


How can I fit Schwalbe Marathon Plus 28-622 tires on a 622-16 rim? I am having difficulties installing Schwalbe Marathon Plus tires (ETRTO 622-28 700x28C) on Jalco DRX-20 rims (16-622). If I am reading the Sheldon Browns tire sizing guide correctly, this is not a problem with tire width. I've tried this technique but the tire is too stiff to install it without levers. Last time I did it I broke two composite levers, this time I pinched two tubes. Previously I had a slightly wider rim (perhaps 18-622, but don't remember exactly) and while it was a little tricky to get them on, it was still do-able even without levers, whereas now I am thinking it's not possible. Is there any other tricks for how to get the tire on the rim? Could width be a factor in how difficult it is to fit?
I'd be grateful for any advice.

Marathons are a known-pig of a tyre to fit to any rim.  You're not alone.

The first fit is always hardest.  After that they go a little easier.

Use three tyre levers, ideally ones with thinner blades/scoops/shovel ends.

Leave the tyre lying flat somewhere warm for a while before you start.  This brings the rubber to a slightly more elastic state.  Hanging up on a hook tends to slightly deform the tyre.  I suggest you wash your rims while the tyres are laying out in the sunlight.

Wash your rims - it doesn't help get the tyre on, but you'll be less dirty and you'll have a better grip.  Take the chance to renew your rim tape if needed - and if you do, use a thin tape not layers.

Now the hard bit.  You want to get one bead into the rim all the way around.  Make sure your tyre rotation is right at this time (guess how I know this...)

Then fit your tube's valve through the hole, and then lay the tube in the tyre. Leave the tube fully deflated.

Starting at the valve, get the second bead into the rim.  Work around and at some point it will just stop popping over the rim's flange.

The trick now is to use velcro ties, tape, cable/zip ties, or even string.  Go back to the valve, and make sure both tyre beads are sitting in the deepest valley of the rim.

Here's the profile of this rim so its not a lot different in the middle.

Many bike rims have a cross section profile like this:
  where you can see a lot more space to be gained.

(semi-related - car tyres are extremely hard to manipulate.  So they often have a massive valley in the rim for helping get tyres on and off and for strength.)

Use your straps around tyre and rim (ie pass between two spokes) and cinch it down firmly to hold the bead in the valley.  Work away from the valve in both directions.  At least 3 ties, maybe a 6 will be needed. I like velcro ones cos they're reusable.  My little 12" tyre went on with just 2 ties.

   LOOSE
Notice the line around the tyre sidewall just above the rim?

Also while doing this you want to "pull" the tyre to gather up all the slack possible and draw that extra around to your last working area.

  Imagine you're trying to get into some really tight cycling bibs/tights/knicks and you get the idea.

Back to the working face,  use your tyre levers to slowly work both ends of the overlap.   Do be careful to avoid pinching the tube  cos it would suck to do this again.

  Notice the amount of "slack" tyre at the top of the image.  There's roughly 8mm of tyre exposed, and at the bottom that same line is below the edge of the rim.

If its just not working, you can use a spray bottle with clean warm water and some dish soap to lubricate the rim area.  Never use oils or grease.  The dishwash liquid will wash off easily and if trapped in the bead will do no harm.

Some people find this process easier with a helper - a third and fourth hand are quite convenient too as are a second pair of eyes.

Don't worry about the future - once the tyre has been on there for a while it will be slightly easier to remove and refit.

Some people swear by the Quick Stick / Stik

And some people prefer the X tool

I've never used the former, but I own the latter and while its interesting is only slightly different to normal, quality tyre levers.


How to choose between a race bike like a Madone and a classics bike like a Domane I ride regularly for exercise in New York City but do not race. I currently ride on a steel frame that handles the rough roads easily. I want to buy a carbon bike and am torn between a "classics" bike like a Domane or a Roubaix and a race bike. My rides are usually around 2-3 hours so comfort is nice but not essential. I appreciate quickness in traffic and am comfortable with a race bike geometry but am worried about durability. Any advice on how to think about these trade offs?

I think you answered your own question when you stated "I don't race."  I know many in our club who enjoy the Roubaix.  I personally prefer riding my steel Soma ES over my carbon race bike for most things, including fast club rides.  Don't get me wrong, a twitchy race bike is great in a crit, but the other non-race bikes have had their design optimized for non-race road riding.  It is too easy to get up caught up in all the bike porn the industry pushes.  A solid, well sorted, well maintained, properly fitted road bike of any class and age can be a great riding tool.

In the end this is just all opinion, but I would be careful not to get caught up in the industry's push for "race" performance, which only serves a small minority of road riders.


What is this thing called that holds the gear shift cable (not the wire)? There is a small metal part that keeps the gear shift cable in place, so the inside cable can move without the cable hose moving as well. I think I damaged it slightly when making repairs so I need a new one, but I have no idea how that part is called or if it is something specific to my bike. I have a Shimano Nexus 8 internal shifter.

I attached a photo of the part standalone and installed.

In Shimano-ese, it is part of the "Outer Receiving Unit."

You can pull up the exploded view diagram for you specific hub model on techdocs.shimano.com to corroborate what you need. Then you can google around for "shimano outer receiving unit" and get the right part number for your hub on the off chance that it's different for the different Shimano internal hubs.


Converting 80s bike to indexed shifters I've just bought an early 80s steel framed bike with unindexed stem mounted shifters. As I plan to use the bike for commuting, I'd like to change the rear mech to use trigger shifters.

I'm not so bothered about converting the front mech at the moment, although I assume it's a similar (if not easier?) process.

The rear dérailleur is a Shimano Tourney (couldn't see a date - it's not new though) and there are 5x2 gears. The gear spacing is definitely less than 10mm although I've only tried to measure it with a ruler.

I've read lots of guides about doing this conversion, but I'm a little confused about what I actually need to do in my case.

I think the rear dérailleur is fine and doesn't need replacing. And I think that all I need is some trigger shifters, but I'm worried about the indexing and spacing. I've read that faster triggers are less likely to suit the spacing, but I don't know why?

Am I on the right lines? Thanks!

Stick with the friction shifters. Changing a non indexed bike to index is expensive and unnecessary.

You will need a new dérailleur to index correctly along with a rear wheel that can mount a cassette (assuming your running a freewheel). You will also need new shifters which if your running a road bike are very expensive.

If you must have index shifting I would recommend a late 90's bike with index shifting already installed. They are generally very cheap second hand and don't require a complete overhaul.

I have an old 80s Apollo road bike that I use for wet weather commuting. I was thinking of doing the same thing and upgrading to indexed shifting. I installed new wheels (Mavic Aksiums) and added a seven speed cassette to the rear hub. I stopped there because the bike ran brilliantly. The new wheels are much lighter than vintage wheels and the hubs are much smoother. A worth while upgrade.

You will get used to using friction shifters very quickly. I actually quite like them now even for commuting.


Is there any reason I can't convert a 36/46 to a 36/52 chainring? My commuter bike is a converted cross bike (really just a cross bike with a rack on it).  It works great, but I occasionally wish I had a higher top end gear.  The crankset that came on it is a 36/46 cross gearing.  Is there any reason I can't just swap out the 46t chainring with a 52t?  It's all Ultegra 6800 stuff, and the cassette is an 11-32 cassette. I guess my biggest concern is that the chain might not be long enough if I ever cross-chain the 52t chainring and the 32t cog.

My guess is: since 50/34 and 11/32 works well, because it is commonly used, so should 52/36 and 11/32. Same tooth difference (16) between the front chainrings. Same total capacity (read further).

Take a look at this technical document
For Item 11 (inner chainring), it says Chainring 36T-MB for 46-36T/52-36T
For Item 12 (outer chainring), it says Chainring 52T-MB for 52-36T
I think you can conclude from that: 52-36 is supported by Shimano.

Now for the rear derailleur:
Ultegra RD-6800 comes in two cage lengths: short (RD-6800 SS) and long (RD-6800 GS)
Use this post as a guide to choose between the two.
Your total capacity becomes 32 - 11 + 52 - 36 = 37.
That's the maximum for the long cage.

Now about the chain:
This video illustrates perfectly how to determine the correct chain length. It shows that you need to use the inner chain ring and the smallest cog on the cassette (36-11). If you follow this rule, your chain length should be OK. Indeed the rear derailleur will be stretched even further than it already was in the other extreme (52-32).

Also an interesting read: Sheldon Brown's take on derailleurs


What is a recovery ride? I often heard this from other bikers where they do recovery rides the day after a long ride (greater than 100kms). What is it for and is it really needed?

A recovery ride is a ride where you go at a very easy pace for 90-120 minutes.

The idea of it is to give all those over-worked muscles some gentle exercise so that they don't tighten up, while flooding them with nutrients to help them repair.

For people in training, it's a day off to just enjoy riding.

I ride with a friend on his recovery ride because I'm the only rider he knows who won't half-wheel him. We go for a nice easy (for him) 50km, and talk about anything except his training.

See recovery ride.


Bicycle clicking awfully, with video I'm getting tired of debugging this noise, which seems to come from the back. I have sent it to the bike shop, for the second time, and they couldn't fix it. This sound came around 2 weeks after I bought it.It's not just sound; you can feel it in with every pedals revolution.

They guy said the bottom bracket was loose, and that he greased, lubed and tightened everything. For a while it was smooth, but 2 hours later it returned. It seems to come from the back (I always believed it was the pedals because you felt it there), but once I went down and got a friend to ride it it most definitely comes from the gears in the back. It can't be replicated but under tension and the most use the worse it get. I only use the bike to go to work, I honestly don't know how it got that bad.

============

Update: they replaced the casette and I haven't heard the sound so far.

I guess you need to be methodical about discounting possibilities.

It sounds like bearings slipping around but a lot of rattles and clicks sound similar on a bike.

Have you got any spare pedals you can put on to see if it's them? Even just borrow a mate's set for 10 minutes.

Given that it always seems to be at the same parts of the pedal rotation I would discount the rear of the bike since the alignment of everything there varies with gearing.

Check for play down at the bottom bracket.

Make sure the axle doesn't shift side to side and that the crank arm on the non-drive side is sitting snugly enough to the bottom bracket.

Take the crank shaft out and check the bearings yourself. Are you short of some balls in there. Did the bike shop do as they said?

Get a new bottom bracket. They're often cheaper than you'd expect and fitting them isn't too bad. Even fitting press-fit bearings is easy with some threaded bar and some big washers. Of course your LBS can do this too.

I've had some creaks on my bike which happens to be carbon but because of this, the seat post noise seams to travel and sounds like a bottom bracket creak. It turned out to be fixable with a wipe down and some carbon paste in the end. Do something similar just in case. It certainly can't harm.


Find or fabricate a metal bracket for bicycle trailer My family and I just recently jumped into cycling. We bought two bikes for my wife and myself and a pull behind trailer for our 1.5 year old little girl. Problem is, my bike has a very small point where the hitch adapter can be mounted.

The stock adapter is shown here, the smaller part attaches to the rear axle:

Where it should, but can't, be mounted on my bike (don't mind the tape measure starting at 2, that's a habit from contracting work, basing off the first visible inch as an offset):

I went to Home Depot hoping for a bracket that would allow me to offset the stock adapter, and found a gate hinge that actually worked, but the metal was too soft and bent. I drew up a representation of what I think I need to make this work, but I don't know what to call it in order to see if a part like this even exists anywhere.

Concept:

If I need to fabricate one, any tips? I don't have any metal working tools besides a drill.

UPDATE: The simplest solution was what worked. Performance Bike didn't have skewers that were any longer than my rear (120mm I think), and I even tried to rig something up on the rear eyelet (M5 0.8mm) but just couldn't get it to fit. Even if I had, I wouldn't have been very confident in it. This morning I was hooking the adapter up to my wife's hybrid, I pulled her QR skewer off and it looked longer than my 120mm - and it was. In fact, it fit perfectly on mine with the washers, and mine fit just fine on hers. I took it for 12 miles and it worked very well. I agree with @Móż that a solid spacer would be better than the washers, something I'll order soon. If I can find clamps like @Criggie suggested I think that will make the best long-term solution, but they were pretty difficult to track down.

I'm curious about why you bought a trailer without checking that it would attach to your bike. It would be better to return it, taking your bike(s) into the shop, and get them to find something that works. You're already suffering from the sunk cost fallacy (you bought something that doesn't work and your proposed solution is to spend more time and effort on it). Will a half-arse bodge job really be better than just buying the right tool for the job? You want a bike and trailer to tow your baby daughter. Try to work towards that, rather than getting caught up in "I have a banana, a bicycle and a trailer"... this isn't a logic puzzle.

If you can find a longer QR skewer you could put a spacer between the frame and trailer hitch. Longer skewers are made, the people who make BoB Trailers sell a setup to attach their trailers to QR bikes for example. At the very crudest level, a stack of 10mm or 12mm nuts will work, but a bike shop should have axle spacers that will work slightly less badly. You should keep the trailer hitch as close to the bike as possible, preferring more spacer on the outside of the hitch.

Since you don't own any relevant tools, I think designing or fabricating an adaptor would be a bad idea. You don't have the necessary skills. If nothing else, when it fails you will be left with two objects, each of which is easy to move, but moving both of them at the same time will be very difficult. How will you wheel the bike at the same time as dragging the trailer once the hitch breaks?

Too many comments, time to edit them in:

Expecting a racing bike to fit a child trailer is a bit like asking the same of your Ferrari. Don't buy a sports car then take it to the boat dealer and ask that a tow bar be fitted for the boat you want to buy. They have completely different purposes. At least with bikes you can buy a cheap second hand mountain bike to tow the kiddy trailer and you only have to spend $100-$200 (obviously you can spend more - but again, don't buy a $5000 racing MTB)

In chat someone pointed out that if you are new to cycling, towing a trailer is not ideal, and if you care about the contents it's a bad idea. Kids move round, even babies, and add to the number of things to need to concentrate on while riding... if you're not a confident rider you may be better off with a proper load/child carrying bike.

You'd be better off with a single part spacer than washers. They will work, just badly, they will slide on each other so there will be more slop. You're increasing the leverage, making it more likely you'll break the skewer. If you have the budget a proper cargo bike will work much better than any trailer, a "long john" style design is more likely to be available and they work really well for kids. Slightly more like a "normal bike" are the long-tail designs, but they're not great for babies (we have a pile of longtail "mummy bikes" locally, as you can carry two primary school children on one).

Also, buy at least two long skewers. They're fairly cheap, and very likely to break. Carry the spare, so when it breaks you can slot the replacement in and ride home. Assuming your bike hasn't been damaged, anyway.

A search like "carry baby" here will help you get ideas of what's possible. Several of the regulars in chat (link bottom left of every page) have kids of various ages and I expect they'd be willing to help. See also "touring with little kids" and search for "baby seat" (which mostly talks about 1 year olds and over, since that's when you can start to expect them to actually sit up in a seat and not break their necks)


Are all forks the same size i.e 1 1/8th inch? Are all forks the same size i.e 1 1/8th inch?

Looking to replace fork on my road bike and need some guidance

No there are a variety of standards. Off the top of my head;

1" threaded (not common on new bikes)
1 1/8th" threaded (not common on new bikes)
1 1/8th" threadless
1.5" threadless
1.5" - 1 1/8th" tapered
Cannondale headshock size (I think this is interchangeable with 1.5" though)

Typically you can only replace like for like. There are a few exceptions, e.g.

1 1/8th threaded/threadless designs can be used as replacements if the headset and stem are changed as well.
1 1/8th threadless can be used in tapered headtubes by fitting a step-up spacer to the fork crown.

The threaded designs tend to be limited to older bikes or really cheap new bikes.

What bike (make/model/year) do you have, it should be easy enough to work out from that what standard it is fitted with. However if you are unsure any good shop should be able to advise.


Singlespeed Hub - Rear Axle Swap I have two sets of wheels, both laced to surly singlespeed hubs (the older "new" hubs, not the "ultra new" hubs which seem to make this process much easier).

Anyway the wheelset I like better has a quick release rear, and the other has a nutted axle.  After riding the QR for a year, I've found I don't really like it.  I wanted to go QR for easier on-trail flat changing, but since switching to the new (tubeless) wheels I haven't had a single flat.  So I'm wishing I had the nutted axle on my newer wheels, as it felt a lot stronger.

What I'm wondering is if there's a way I can disassemble the hubs and get the nutted axle onto my new wheels.  I haven't taken apart a hub before but as I understand it these hubs use cartridge bearings, which I suspect makes the process a bit easier.

http://surlybikes.com/parts/hubs_v1 says "This is a common size so it’s easy to find replacements should the need arise or to swap axles if, for instance, you have a QR axle and want to go solid", so it should be easy enough.
Based on the photos, you might want some cone wrenches even though with cartridge bearings there aren't actually cones as such. As the Surly page says, you still need to adjust the load on the bearings when you do it up.
http://sheldonbrown.com/tooltips/conewrenches.html


Wipperman connex master link on a shimano chain? Is it possible to use a wipperman connex master link on a shimano dura ace chain? I read a comment on a site elswhere that said this was possible, but is it safe? Or safe-ish?

It should be safe as long as the widths of the chain and the master link are the same. That is, if the chain is 10-speed, the master link must be 10-speed, and so on.
From the legal perspective, I do not think that either vendor (Shimano/Wipperman) will accept warranty claims in a case when something would break. Unless they specifically claim such compatibility, of course.
From the practical perspective, as long as the pieces are geometrically compatible (the aforementioned link width and the pin/rivet diameter), they should work fine together.
From my experience, I've used various SRAM/KMC/Wipperman master links on various non-matching Shimano/KMC chains without issues. Things did break occasionally, but so is the name of the game for me.


Tips for getting sponsored as an individual racer? I'm currently racing a state XC MTB series and will be moving up to Cat. 2 next year. As part of my goals, I'd like to get some sponsorship for the 2014 season. I have a few questions about this though, and I'd love to hear from racers or industry employees who may deal with this.

Form letters: Do you write a form letter/email and essentially send the same thing to every company and hope they bite? Or would it be better to personalize each?
Sponsorship level: How do you figure out who gets to be the primary sponsor and who gets a tiny logo on your bike? Is this done before contacting places, or after amounts/materials have been decided?
Influence of on/off the bike: Obviously you are a brand ambassador of the sponsor, but how much should you emphasize your contribution when on or off the bike. Everyone will see your kit when racing, but will another helmet for dirt jumping help sell the brand too, for example.

I'm not trying to hit WC status in a year or anything, but I feel like being proactive is better than the "look how good I am, now sponsor me" approach.

How To Reach Out
As an individual, you must reach out in person.  I would show up at their place of business, or at the very least call them.  I wouldn't expect anything from a letter - personalized or not.
What You Offer
Now that you're actually talking to someone... what comes next?  What are you going to provide them?
If you're active in the racing community, by promoting races, doing trail work, teaching skills clinics, etc. - then that is what you sell to the companies.
If you blog/write/podcast/tweet and have an active following, then that is what you sell them.
You're Just a Racer
If all you are doing is racing, then you'd better expect to put the time in and get good enough to regularly place on the podium in Cat 1 (not Cat 2).  While racing Cat 2 would be a good start, there are literally hundreds of people just like you also racing Cat 2.  (side note: as soon as you start placing on the podium in Cat 2, you'll likely be bumped up to Cat 1 the following year (or even mid-year, depending on the rules)).
You have to figure out what makes you different than the other 100 guys racing Cat 2, what makes you stand out, what your story is.  If it is compelling, then that is what you sell them.  If you don't have a compelling story, you'd better be winning all the time.
Who Will Sponsor You
I'd start local - ask businesses in your community for sponsorship.
Chances are, if they're willing to provide sponsorship, they'll want to sponsor with what they deal in.  A brewpub might offer you discounted pints, a salon might give you free haircuts, a bike shop might give you discounted prices on parts and labor.  Our team was sponsored by a sign making shop - they give us any sign/banner we want for free - that's an amazing deal (literally 100's of dollars of value if we make use of it) - but probably not that useful for an individual.
If you want sponsorship of a company that isn't small or local... you've got to win.  For example, Kona sponsors up-and-coming racers.  Their 2013 team could be found here: http://2013.konaworld.com/grassroots.cfm  The gal I know on that team won every local (state-wide) XC race she entered, and placed top 5 in the XTerra world championships.  That's the level at which you need to be racing to get that level of sponsorship.  So start local.
Levels Of Sponsorship
If you're a racer, about all you have to offer (in terms of marketing space) is a spot on the jersey.  The bike is just too small a platform to be of any use.  If a part of your agreement is to wear your jersey at bike parks, then get a free-ride jersey dolled up the same way as your XC jersey and wear it at the bike park.
As far as deciding the different tiers of sponsors... when starting out, I'd treat every sponsor as a major sponsor.  If you get two sponsors your first year (Kate's Knitting and Joe's Tire Shop) - give them both big spots on your jersey.  Once you have enough sponsors to need to prioritize, then you'll have an idea of where to draw the line.
Good luck!
Edited to add: Looks like Pinkbike agrees, check out their article "So You Wanna Be Sponsored?"
Note: I'm just a dude who started racing a few years back with a local club team.  I have no experience getting sponsors, but I do know what our team gets in exchange for sponsorship.  Your best bet at getting sponsored is to join a local club team and get the benefits from that.


Problem setting up Shimano 5800 levers for the first time This is my second attempt to setup a Shimano 5800 groupset from scratch.  The problem on both bikes has been that downshifting worked to a point, but upshifting never works. The process isn't detailed very well in the docs, but the following is what I've done.

Tapped the B lever (upshift) 10+ times.
Thread the cable through the lever. Use the correct Shimano provided housing end with extra sheath for the cable. Close the flap. Make sure end is pulled into place for no lever side cable slack. I don't have a third hand tool so maybe my mistake is here.
Attach cable to rear derailleur. Again slack with no third hand tool. Tighten by compressing the derailleur and pulling the cable by hand.
Downshift as far as it'll go. I had planned to set the derailleur adjustment screws once I has in the largest gear.
Now the B lever feels like it's not engaging the cable at all. Unable to upshift at all. B lever does move freely.

I've been through this three or four times and the outcome has been the same. Any ideas what I might be missing?

I managed to fix this, but I'm not completely certain why it started working. I believe the fix was a combination of three things.

Repulling the cable and being firm about pulling it horizontally
through the lever. I don't believe I got it deep enough into the lever before
putting the hood back into place for extra pressure on the cable helped it engage
making sure to start with a fair amount of cable tension before working the levers


What happens if a tire goes flat while I am in a fast turn? So, the other day, I was riding along and got a flat tire.  I was at the bottom of a large hill where I often find myself travelling 30 or more miles per hour (as per my speedometer) about it's many curves.  The tire came off very easily when I was trying to repair it.

Has anyone had this happen to them? How likely am I to die?  Surrounding terrain is quite hostile.

It depends on which tire, but the essential thing is a flat tire has almost no grip.

Two examples:

Two days ago I was descending a little hill at 60 kph (about 35 mph) when the rear tire suddenly went flat. Moving my weight forward as much as possible, I was able to maintain control while stopping using only the front brake. Turns were perilous, because the rear tire, had almost no grip, and kept trying to slide out.
A few years ago I set out on a ride, and foolishly had not checked the tire pressures. The front tire had a slow leak and was at half it's normal pressure, which I discovered when attempting a high speed downhill off-camber turn. With barely any front grip, the bike went almost straight on. If there had been oncoming traffic then I would have hit it.

As for the front tire coming off the rim, several years ago I was in a bunch and some of the bunch were swerving around in the buildup to a sprint. To avoid crossing wheels with the guy coming across me (who happened to be my brother) I had to turn sharply. We were doing about 35 kph at the time, and the cornering force rolled the tub off the rim. If you think it through, losing grip on the road is nothing compared to what happens when the tire that is now not on the rim gets to the top of the forks. The wheel stops rotating. So I was suddenly flying through the air, sans bike.

To answer your question how likely are you to die? Yes it's possible you'll die, if you hit a rock, tree, or oncoming traffic. That possibility depends somewhat on your bike control skills, and also on luck. But it also depends on where you choose to ride and in what manner. Hairy descents are not for busy roads.


Knowing what bicycle frame material I have I have a bicycle frame that's really heavy. It's a mountain bike frame with shocks, so I decided to replace the entire frame with a city bike aluminum frame(I only use the bike if I have to pick up/buy some stuff near home). How do I know if the frame that I replaced is a titanium/steel?

I got the bike as a present from my uncle almost 6 years back, I don't have an idea about the brand, it's just the entire frame is not your average frame, it's somewhat heavier than other bikes( I compared it with the aluminum frame I bought/ plus a couple of my friends bike)

What methods/techniques should I use to know what type of frame do I have?

To identify a frame firstly see if a magnet sticks, if it does it's steel, if not it's carbon, aluminium alloy or titanium alloy.

If not steel look down the seat tube if it's metallic inside it could be aliminium or titanium if black and plastic looking, carbon. Tap the frame with a screw driver, aluminium and titanium will have a definite metallic 'tink' and carbon a hollow 'thunk'.

To tell the difference between alloys put a small scratch in the seat tube (both have good anti-corrosion properties) if the exposed metal is dark and dull silver it's possibly titanium, if light silver it's aluminium. Titanium frames are expensive and rare so not likely to come across one you don't know the pedigree of.

For steel there is a significant difference between the two main types of steel, Chromoly and Hi-Ten steel. Chromoly is a stronger and lighter (high carbon) steel and is generally found on mid to high end bikes. If a bike is reasonably modern and chromoly it is likely to have smaller diameter tubes and possibly seat post (although this isn't a good indicator as new steel frames are being produced to fit dropper posts). A chromoly bike may have a sticker on the seat tube from the tube manufacturer be it Reynolds, Tange or Columbus. Tube shape may also vary on higher end frames (my chromoly HT has a triangle top tube and oval down tube). A Hi-Ten frame will mirror the fashion of when the bike was made.

Few Chromoly frames come as built up bikes so generally if you don't know your riding Chromoly, a magnet sticks to the bike and it's heavy you're riding a Hi-Ten steel bike. The scrap value of the frame is probably worth more than the frame.


How do bicycle power meters work? What exactly are they measuring? How do they measure it? What are the implications of the different approaches on accuracy / speed of getting a good measure?

It would be helpful if someone could give an answer that explains how hub-based meters like the PowerTap differ from the crank-based meters like the Quarq which differ from the other ones.

There are several different types of power meter on the market and each measures something slightly different in order to make their estimates. In addition, the way that they measure what they measure has implications for their accuracy. Below I discuss what the major models measure, how they measure it, and the implications for accuracy.

Power is the rate of work (so you need to know the amount of work and the span of time over which that work is done), and work is a force exerted over a distance, so each power meter has a different way to measure those forces and, because of patents, each has chosen to measure them in a different "location."

With the exception of the iBike, most power meters measure the forces somewhere along the drivetrain: working from the back to the front, the PowerTap (and the old Look MaxOne) measures at the rear hub, the older Polar systems measured along the chain, the Quarq, SRM, Rotor, and Power2Max measure at the spider of the front chain ring, the new Look/Polar and Garmin Metrigear (thus far, announced but unreleased) measure at the pedal spindle, the (announced but unreleased) Brim Brothers measures at the shoe cleat, the Ergomo measured at the bottom bracket, and the Stages measures at the left crank. The iBike measures in a completely different way, discussed below. One consequence of measuring at various points along the drivetrain is that drivetrain losses will (or won't) be accounted for to a different degree; for example, a PowerTap will usually read lower than a SRM since one is "upstream" of most drivetrain losses while the other is "downstream." This difference is more of a definitional issue than a strict "accuracy" issue (in the sense of, "is gross income or net income a more 'accurate' measure of income?" Unless you have a specific use in mind, it's hard to say which is more "accurate").

Most of the power meters on the market use strain gages, which are small thin foil strips whose electrical conductance and resistance varies as they are deformed. Strain gages are used in lots of applications (like, bridges) and their properties are well-understood. In general, strain gages are combined in a "rosette" or "Wheatstone bridge" in order to produce more accuracy and precision (more strain gages usually produce better results), and, when operating properly the Power Tap, Quarq, and SRM are usually accurate to within a couple percent (and, just as importantly, with high precision); this has been verified both statically (using known weights hung from the crank) and also dynamically (using a large powered rolling drum in a lab). The forces are then combined with a measurement of angular velocity or speed to get power. A virtue of strain gages is that the change in resistance can be measured even when the device is stationary so the cyclist can measure the accuracy of the strain-gage-based power meters at home by hanging weights of a known mass from the crank. A common problem with the strain gage approach, however, is that they can be sensitive to changes in temperature and so need to be "re-zeroed" prior to (and sometimes, during) rides. The old Look MaxOne's achilles heel was waterproofness, not the strain gages or method of measurement. For example, the original Power2Max (and the old discontinued SRM "Amateur" model) uses fewer strain gages than the current PowerTap, Quarq, or SRM models and reports from users (subsequently admitted to by the manufacturer) showed that it was more sensitive to temperature drift during a ride than those others. The Power2Max was redesigned and updated in late 2012 and reports are that the temperature problem has been largely addressed. A claimed feature of the Stages is that it is designed around automatic temperature compensation — as of early 2013 this claim is still being evaluated by users and it is too early to know if their approach does what it claims.

The old Polar power meter measured the force transmitted along the chain by chain tension, and included a chain speed sensor to get total work. In a chain higher force transmitted along the chain results in higher tension, and tension can be measured by the resonant frequency of the object (for example, plucking a highly-tensioned spoke with your fingernail produces a high frequency tone while plucking a loose spoke produces a low tone). As an historical aside, the proof-of-concept prototype for the Polar chain tension sensor was the pickup from an electric guitar. The chain speed sensor fit on one of the derailleur jockey wheels and could count the "pulses" in the magnetic field as the chain rivets passed; since chain rivets are a known distance apart, chain speed was easily calculated. As for accuracy, when the Polar was operating well, it was very good; however, when it wasn't it was very naughty indeed. Worse, it was often hard to tell when it was being naughty. The downfall of the old Polar power meter was three-fold: 1) the chain tension sensor needed to be close to the chain, which was hard to achieve since the chain sometimes had to be in the large or small chain ring or the large or small rear cog; 2) the chainspeed sensor sometimes got overwhelmed and gave false speed readings; and 3) incomplete weatherproofness in part due to exposed wires and a poorly sealed "pod."

The Ergomo bottom-bracket based power meter used an optical sensor and a series of "peek holes" to measure torsion in the bottom bracket. An odd characteristic of this design is that it could only measure the (torsional) force traveling through the bottom bracket; thus, it only measured the power contributed by the left leg: to get total power it doubled the left-leg contribution. In conjunction with the difficulty in installing and calibrating the Ergomo (it had to be installed just exactly so), this dependence on bilateral symmetry between the legs was the death knell for the Ergomo. The Stages power meter similarly measures force by deformation in the left crank, and doubles the "left" to arrive at an estimate of total power. Research with instrumented force pedals shows that bilateral asymmetry in power production between the right and left legs is the norm — worse, the research shows that the asymmetry can change with the level of effort. However, some riders are willing to accept this inherent inaccuracy and imprecision.

Because neither the old Polar nor Ergomo power meters used strain gages, their accuracy and precision could not be statically checked in the field by the cyclist; they could only be checked dynamically (or against anotheher known-calibrated power meter).

The unreleased Garmin Metrigear and Brim Brothers pedal or pedal cleat power meters are rumored to use piezoelectric sensors and solid state accelerometers rather than foil strain gages but until they reach the market all claims about accuracy or precision should be taken with grains of salt. An interesting problem in the design of a pedal- or cleat-based power meter is that the direction of force and the position of the pedal spindle must be known: for example, if you add downward force at the bottom of the pedal stroke, that is wasted force since it does not aid in moving the crank in the correct direction; likewise, if you press down (however slightly) on the upstroke, that will cancel out some of the force exerted by the other leg on its downstroke. Keeping track of the various force vectors is therefore key to getting reliable accuracy and precision. To some extent, the Stage power meter can also occasionally be susceptible to a related problem: the Stages uses a solid-state accelerometer in the pedal (similar to the solid-state accelerometers one can find in smart phones) to determine its position. Early production models of the Stages were plagued by imprecise measurements of pedal position, so pedal speed was also imprecise — and this had repercussions for the precision of the final power estimates.

The recently released (as of January 2012) Look/Polar power meter uses strain gages arrayed along the pedal spindle, and each pedal must be carefully installed so the pedals know which direction the forces are being applied -- a special tool is supplied with the pedals to help with the orientation. To simplify the conversion of measured forces to torque values, the Look/Polar pedal allows the use of only four different crank lengths: 170mm, 172.5mm, 175mm, and 177.5mm. Cranks shorter than 170mm are currently not supported. One pedal is the "master" and the other is the "slave"; the slave pedal transmits information to the master which then bundles data from both pedals and forwards it to the head unit. At the moment, the Look/Polar pedal uses its own transmission protocol and no other manufacturer has yet signed on to provide compatible head units. Early reports on the new Look pedals confirm that the orientation of the pedals is critical: because the spindle of a pedal is small, a small absolute error in alignment can be a large relative error in its angular orientation.

The iBike takes a completely different approach: it calculates power indirectly. That is, you need a certain amount of power to overcome changes in potential energy (climbing or descending), for changes in kinetic energy (accelerating or decelerating), to overcome aerodynamic drag (including the wind) and drag from rolling resistance so if you know ground speed, gradient, wind speed, your total mass (you plus bike and all equipment) then combined with estimates of the coefficients of rolling resistance (Crr) and of aero drag and front surface area (CdA or drag area) you can calculate the overall power (see, for example, here). In essence, the other power meters on the market focus on the "supply side equation" by measuring power supplied by the rider somewhere along the drivetrain; the iBike focuses on the "demand side" by measuring power demanded to move the bike against wind, gradient, and other drag forces. Under normal conditions, this can be quite (perhaps even surprisingly) accurate, though the precision of the power estimated in this way is not as good -- the iBike assumes that the aerodynamic drag area (aka CdA) is constant, so if the rider changes position (say, moving from the drops to the bar tops) or if the wind speed differs because the yaw angle changes, the power estimate will be off. In general, the iBike has been shown to be quite accurate for hill climbs; less so for rolling courses or riding in a pack, so the overall accuracy will depend on the exact mix of riding done and the variability in the direction of the wind. As with the non-strain gage based old Polar and Ergomo, the iBike cannot be statically checked for accuracy or precision; worse, nor can it be checked on a dynamic rig in a lab since it depends on gradient and wind speed. Checks of the iBike have been performed in the field when riders have mounted another power meter on the same bike and compared the two data streams.

There have been a few "simultaneous" comparisons of power meter accuracy where one rider mounted two or more power meters on the bike and went on structured or unstructured rides. You can see one such "Rosetta Stone" comparison here and here.

In general, all of the commercially released power meters have been accurate (and sometimes precise) when newly-adjusted and performing under ideal conditions. However, conditions are not always ideal and parts get damaged, dirty, and deteriorate. If accuracy and precision are important then the "design" accuracy (whether based on strain gages, optical sensors, magnetic sensors, or wind speed sensors) is only half the battle: equally important is the ability to verify a power meter at home so you can tell when they're off.


Single bolt seat clamp slipping I've got a Kindshock Dropzone seatpost with a single bolt clamp.

Even if I screw the bolt in hard the saddle will always slide to the back.

Any way to prevent it? It's pretty annoying.

I have never had a problem getting single bolt tight enough to hold.

Most likely is seat rail diameter - 7mm is common road, 9mm common MTB but there are others. (refer Wikipedia).

Is there something assembled wrong, a piece upside down?

Although seat post bolts need to be tight, what ever you do, don't be 'that' "gorilla with a spanner" - it is never the correct approach when assembling bicycles.


I need help identifying used MTB tire sealant I have a new-used MTB and I don't know what kind of sealant is in its tires. Does anyone know what this may be, or have a good resource for figuring it out?

The liquid sealant in the tire is a light brown, like coffee with milk. The dried sealant is a slightly darker brown.

The final result was "don't do that" (where "that" was to try to identify and match the existing sealant). Per advice in the comments I cleaned out the remaining liquid sealant (and the crud where the sealant had pooled and hardened during non-use), cleaned the inside with isopropyl alcohol and a lint-free towel, and then set the tires up with the sealant I have on hand (Stans). They have been holding pressure and riding great.


Polite way to ride in the dark Sometimes I ride in the park which has no light. There always are dog walkers, runners and other cyclists.
So, when I ride towards someone I have two options:

dim my light and slow down (since I can't go fast anymore)
speed up to to minimize time that I light on those people

My front light is:

So, the question is: how to be less irritating?

Consider how you feel when a fellow cyclist approaches you will full beam straight ahead. It's pretty blinding, even for a moment, and especially off-road when your eyes aren't used to it.

So in a park:

Dim your light to its lowest setting (within reason).
Put it on steady beam. Flashing is more visible but also more annoying and
disorientating.
Physically push it forwards/downwards so it's pointing towards the ground, not into anyone's face.

If you do this then it doesn't matter whether you illuminate pedestrians or for how long.


Replacement fork has forked up my bike A little while ago, a year or so, I changed the cheapish steel fork on my commuter for a cheapish carbon bladed fork I had hanging around. The headset on the bike is a little non-standard but the shop that did the work for me (moved the crown race over) assured me that it would be fine.

Since then the handling of the bike has been atrocious. The new fork has a greater rake and a longer steerer but the handling of the bike is now really unsteady and twitchy. The other issue is that it's suddenly really difficult to get the loading right on the headset, a sixteenth of a turn in either direction and it's far too loose or far too tight.

The new fork has a greater rake ... but the handling of the bike is now really unsteady and twitchy.

The greater rake reduced the trail.  The trail the distance between where the pivot axis of the fork meets the ground and where the tire meets the ground.  The greater rake moved the front wheel forward, towards the pivot axis of the fork.

It's like the front wheels on a shopping cart.  The wheel points in the right direction because of the force from having the contact point behind the pivot axis.  A smaller trail reduces the forces that keep the bike going straight.

See the Wikipedia article on bicycle and motorcycle geometry:  https://en.wikipedia.org/wiki/Bicycle_and_motorcycle_geometry#Trail

  The other issue is that it's suddenly really difficult to get the loading right on the headset, a sixteenth of a turn in either direction and it's far too loose or far too tight.

That sounds like the bearings might not have been properly installed - an incorrect crown race (wrong angle?) or something like that.  How do you know they moved the old crown race over?  They're not hard to get off with the right tools, but a little impatience during removal can result in a bent crown race. Maybe they cleaned off all the old grease and didn't re-lube it when installing the new fork?

Without details, it's almost impossible to do anything other than guess at the cause of this problem.


What is the men's version of Trek Lexa SLX Trek used to make only "WSD" versions of the same model names sold "for men."  But things aren't that simple anymore!  What's the men's version of the Lexa SLX?

Looking around their site, the Madone 2.1 seems to have similar components, yet is only $1,319.99 compared to the Lexa which is $1,649.99.  Looking over the specs,  I can't see why there is such a discrepancy in the price.  The Domane 2.3 is also quite similar and has the IsoSpeed decoupler on the frame and appears to hace rack mounts based on the picture. It is priced at $1,869.99.

There also seems to be a substantial price difference between the Silque and the very similar Emonda S4, which are priced at $2,089.99 and $1,649.99 respectively.  It's interesting that the women's specific models seem to be so much more expensive.  Maybe there's something I'm missing out on with the pricing.


Hydraulic Vs. Mechanical disc brakes What is the difference between hydraulic and mechanical disc brakes? Are hydraulics more reliable? Or more powerful? I'm curious since, hydraulics seem to get more attention and seem to be on professional bikes.

Hydraulics are used on higher end systems, cables are often a sign of a cheap brake set, so your observations are correct regarding "professional" bikes. However there are very good cable disc brakes (e.g. Avid BB7's) that are the exception that proves the rule. .

Cables have the disadvantage of friction that hydraulics virtually eliminate. It is significantly easier to modulate hydraulic brakes, you get more force delivered to the pads, hence more stopping power for the same input, and faster/more reliable and predictable pad retraction when releasing the brakes.
As the Hydraulic system is sealed, grit and grime cannot get in to jam up the moving bits, making them virtually maintenance free (replace worn pads is about all need doing)
Hydraulic systems are also easier to set up and adjust (with the right tools - next to impossible without them). Cables have to the exact length, and need "tweaking" as they stretch from new.

That said - a good quality and well maintained cable system will out perform a poor quality, cheap hydraulic brake set, so you cannot state "Its hydraulic therefore it's better".

Disadvantages of hydraulics occur when you get a leak such as hole in a hose or blown seal. They are less "field serviceable" than cables, essentially the brake is rendered useless and unrepairable (in the field) by a minor fault - which fortunately happens very rarely, and usually caused by poor transport rather than while out riding.

Another reported problem with hydraulics is boiling of fluid. This is more of a problem on road bikes where mountain descents of 100's of vertical meters in a very short time are more common. With overheated fluid initially the pressure in the system stops the fluid boiling. When the brake is released (even for a moment), the pressure comes off and fluid boils, and the brakes no longer work - at all - the lever just goes all the way in. Another thing that can happen is the rider stops with no problems, but the heat in the calliper (no longer being cooled by airflow) migrates to the fluid over the next few minutes, so when the rider rides off there are no brakes.  (This is different to disc fade where the pads and disc overheat and brakes loss effectiveness slowly - both types suffer this equally.)

Watch out in the future for Hydraulic shifters.... Available now if you have the big $$$$, lighter weight than XT and XX level components, almost certainly more reliable and easier to setup.... (Update 2015- Electric shifters mean these will not become main stream.)


Reason behind the Tour Down Under "People's Choice Classic" The Tour Down Under (TDU) is technically a 6-stage race, but the day before is the "People's Choice Classic",

  The People's Choice Classic, also known as the Down Under Classic, is a single day road cycling race held in Adelaide, South Australia, Australia. The race is the official warm-up for the Tour Down Under. Founded in 2006, the race exists as a men's only competition

The race is the day before Stage 1, but it doesn't have any bearing on the Tour Down Under, and riders don't earn UCI points.

Is there any specific reason this is not part of the TDU?

My first thought was it's good for attendance/marketing/etc for "the race" to both start and finish on a weekend (and both take place very near the city-centre), but there might be some UCI rule preventing a 7-stage.. but this theory is completely unfounded (I couldn't find anything to this effect in the UCI rules/race-guidelines)

It's complicated, and this may not be all there is to it.

From my reading of part 2 of the UCI WorldTour regulations (p43-44) is

The duration of new "Continental" events is 5 days, unless the event has an exemption from the committee. Existing events have the same duration they had in 2004. The Tour Down Under went for 6 days in 2004.
A prologue can be included if

It does not exceed 8km.
It is time trial.
It counts as a race day.

This all confirms your suspicion that it's due to the rules. The Peoples Classic was 50km, and was not a time trial, so it couldn't be part of the TDU. As you say, it was good for attendance and marketing (and publicity).


Is my front brake installed correctly? I bought and installed Shimano MT200 brakes to my bike and now I'm wondering are they installed correctly. Seems like only small area of pad is touching the rotor. 160 mm rotor in the front. I had some bad Tektro mechanical brakes but replaced them with these Shimano MT200 hydraulic ones.
Pictures of different angles: https://imgur.com/gallery/WAiZkjc

Your brake is certainly not properly set up. Do not ride the bike in this state!
The rotor's brake track must run fully between the brake pads. The radial dimension of both match.
You rotor may be too small for the brake it its present set up, your wheel not properly inserted, or the brake caliper not mounted correctly.
Check your brake's manual for adjusting it to different rotor sizes with adapter plates. Often an adapter can be flipped to accommodate 140 mm and 160 mm rotors.
As general advise: do not fix it yourself.
Ask someone who knows what they are doing, for example, a certified mechanic. That you have to ask this question indicates you are not ready to tinker with brakes that are relevant to rider's safety.


inferior/weaker rims vs superior/stronger rims with an underweight cyclist I want to ask a physics-related question, I'm a male, 162cm, height 50kg/110lbs (I'm healthy, but too light!).

Right now I'm building a Surly Cross Check and I'm confused what wheels I should purchase. So I have two options: Alex DM18 (cheap) and Alex DH19(more expensive). They have similar inner rim width (17.9mm an 18mm). I really want DH19 but I'm little bit overbudget on other parts. I plan to use my bike for commuting and a little bit offroad. If I use the bike for offroad, do DH19 rims will stay true longer? Or because I'm thin, would using DM18 have insignificant difference?

Edit: the plan is to build an ss cx bike, no consideration of cassette/drivertrain

You get what you pay for. The DM18 is a cheap rim with good enough reviews rating it good value for money. The DH19 is a better rim - only you know if you can or want to stretch your budget, however "Quality is remembered long after price forgotten" comes to mind. Are you prepared to regret not spending that extra money every time you go for a ride?

Provided the wheel is built well and maintained, the cheaper rim will stay true (its the spokes that keep the rim true, not the rim). The DH19 has eyelets for the spokes - meaning the rim will handle more abuse and last longer (without eyelets the spoke holes tend to fatigue and crack). However, as you are only 50kg, I expect the cheaper rim will easily handle the riding you are suggesting. If you were 150kg, I would steer you to the DH19.


How does the frame split on the 2016 Novara Gotham belt-drive bike work? I am considering purchasing a Novara Gotham with the Gates carbon drive (2016 model), and before I purchase I am trying to determine how the frame split works on it. The pictures in REI's online store indicate that it may be a welded gap in the seat stay, which I find somewhat difficult to believe - that would require rewelding the frame to replace the belt.

How does the Gotham's frame split work? Where is it located, and how does it come apart/together?

I edited a photo of the relevant part of the bike into the question, but then decided to answer it. I can't find a photo showing any more detail than that, sorry.

The two weld bumps on the right hand seatstay will be where the the frame joiner has been put in, and resumably there's a bolt or two in there, but I can't find out, sorry. OTOH, it will almost certainly be easier to open that up than to find a replacement belt, so I wouldn't worry about it. It will definitely not require welding to do that, though.

This search for "belt drive frame joiner" produces a lot of hits, including an image that looks as though it could be the device used in that bike.

Image from road bike forums where there is a thread discussing how that device was installed in a frame. If it was turned so the bolt heads were on the inside of the frame, it could look like the Novara Gotham. Or they could have an equivalent design.

I'm looking at the gap between the welds above and I think there's a faint stripe in a slightly different colour, suggesting a centimetre wide chunk gets unbolted from the seat tube. But it's very, very faint.


Does anyone make a spacer for SPD cleats? I have a pair of cycling shoes that accept a two-bolt cleat, but require a spacer between cleat and sole to be compatible with Shimano SPD pedals. My pedal and cleat package did not come with spacers.

Does anyone make spacers of varying heights for such a situation?

As Kibbee said, making your own out of a milk jug or soda/beer can is probably the easiest way to go.  The spacer doesn't need to have the exact same footprint as the cleat to work, so you don't need to be too concerned with the sizing/shape.


Removing bottom bracket from 79 peugeot frame I would like to remove the bottom bracket from an old french peugeot race frame. I believe the frame was built in 79 judging by the decals and stamp on the bb.

The bottom bracket and spindle at the moment will spin, but feel very dirty and sounds gritting so I want to take it apart to clean/regrease.

I'm almost certain its a french bb and not swiss based on the info on from cyclespeugeot.com.

I'm about ready to start this but have a few questions.

From what I have read, I only need to remove the left adjustable cup to service the BB?
The left adjustable cup will be left threaded so will need to turn clockwise to undo?
Is the lock ring also left threaded? It has an outer diameter of 47mm and i'm currently struggling to find a locking ring tool to fit.

I'm trying todo this properly as it seems getting a new or used french bb is not going to be worth it and I might as well get another frame.

If it helps, here are a couple of pictures:

Usually one only needs to remove the left cup to service the bottom bracket. With Fench/Italian BBs the right cup is usually so tight it's not worth even trying (I personally attempted two times but never succeded EDIT. I also managed to damage a Park Tool BB remover, worth 15 quids...)

The left cup is always right threaded, in any case the lockring must have the same thread orientation of the cup.

As for the oversized lockring, I have had a good rate of success using adjustable pliers, just hold them tight enough so to avoid losing grip.

Finally, it's always worth repairing, or at least trying to!


Full suspension or hardtail for offroad in South Wales I mountain bike in the hills of South Wales. I am due a new bike and have been riding a 17kg full sus for a few years now. I mostly ride 15-20 miles every week (hopefully more when the summer arrives) of moderatley technical terrain and the occasional trail center and big ride. I'm of average skill and a fairly hefty guy at 14.5 stone and often give the bike a good few knocks and abuse.

I cannot decide whether to buy a full suspension or hardtail bike. My budget is £1000. There are a few half decent full sus' bike around for under this with the current sales. Also a load of really good hardtails. Can anyone point me towards something suitable?

Yes there are a few full suspensions in that range, they will be heavy, and mid to low level parts. Saving a bit longer and waiting (hard i know) Maybe £1200 - 1500 would get you much further.

Your current bike is 17kg. a £1000 bike may only save you 1 - 2 kg. A nice hard tail within your budget would be very light (12 - 13kg)

Another option would be a 29er. the bigger wheels, and high volume tires will really help with overall comfort and capabilities on rocky technical trails, while still being fast and lighter than the full suspension in that range (but likely still 14 - 15kg)


Run without a derailleur hanger? I'm building a bike on an old aluminium frame that is missing the rear derailleur hanger. I'm putting an IGH on it, so I don't need to use the hanger, but the dropout seems too thin without it. Can I do without, or is it necessary to avoid bending the dropout somehow?

Most aluminum frames have a replaceable derailleur hanger, which typically is part of the dropout itself as you can kind of see in this image:

Without it, the dropout is indeed too thin and your spacing is messed up, not to mention that the strength of the dropout is decreased. You need to identify the correct replacement hanger and get it fixed.

Also, I don't know what IGH you're using, but it will most likely require some sort of chain tensioner as well, and without sliding dropouts or an Eccentric Bottom Bracket, you're probably going to need a spring-based chain tensioner that will bolt on to the derailleur hanger:


Can anyone help me to identify my TREK mountain bike model from the serial number? I bought my TREK mountain bike in 1999 when I was living in Germany.
After a few years of use I moved & it kind of got mothballed for the past 15 years for one reason or another.
I am now back on the road and its pretty much like new after some basic maintenance.
My query is what model is it (receipt is long gone).  Info that may help:

Serial number is: S99050362 (nothing on the http://www.vintage-trek.com/ looks relevant)
27 Shimano gears with Deore LX M570 STi shifters;
( Silver with black decals colour; fairly light weight metal (aluminium??) frame.

It may be a model manufactured from about 1996 onwards but I bought it in late 1999.
Any insight would be appreciated.
I have trawled the web but the serial number on the frame has no hits.

Pretty much all the yearly Trek catalogs and technical manuals for the 90s and 00s are found here:
http://www.vintage-trek.com/trek-fisher-klein-lemond.htm
There's also bikepedia.com and bicyclebluebook.com if you've got some idea of the model year and/or model number/name