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So I don't have lots of money and just recently the bb on my vintage tube shifter 2x6 road bike broke and I have to make do with a slightly too long bb and mtb cranks because it's what I have. Anyway before I can replace the bb and cranks, I'll have to make do with the big chain ring in the front (48) and the 4 heaviest gears at the back to prevent cross chaining. I find myself going usually on the two middle gears. When stopping at a red light, I don't change gears, but just crank it up slowly while standing until I got to my desired cadence and then sit, though sometimes I got a little excited and sprinted away. I've heard that climbing in too heavy gears can damage your legs, so is this practically the same? will I damage my legs doing it this way? I don't feel pain or anything, but just in case.

  • How long does it take you to spin up to a normal cadence? How often do you stop? You're likely to be spending much less time in that gear than grinding up hill in it. Also what's the lowest gear ratio of those you currently have (including wheel size)? It might not be that different to many fixed gear bikes (which wouldn't do my knees much good but others are fine on them) – Chris H Jan 28 '18 at 16:03
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    If you are standing then there is no significant hazard to your knees. If you pedal in a high gear while seated (especially if the seat is too low) is a hazard. But doing so for only a few seconds in probably not going to cause trouble. – Daniel R Hicks Jan 28 '18 at 19:13
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    It's interesting that people fear cross-chaining so much that, when given the choice of cross-chaining or something they think might damage their knees, they choose the knee damage. – David Richerby Feb 2 '18 at 20:44
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    @DavidRicherby - Don't you understand that cross-chaining is a terrible social faux pas? It's akin to drinking tea without raising your pinky! – Daniel R Hicks Feb 2 '18 at 20:59
  • I've had friends suffering knee injury from riding a fixie with too high gear ratio, sprinting against cars on every red light. So, the possibility of injury is real. However, It will depend on many factors, such as how hard you sprint, how frequently and whether you have a correct pedalling technique. – Jahaziel Feb 5 '18 at 22:07
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No, there is no inmediate danger to your knees. Most dangerous thing can happen is the chain snaps and you ram your knees on your tee, or frontflip over the bars while still.

Most Bmx riders use a equivalent cadence(I think this is the word) wheel to gear ratio, and almost every one rides standing up. Because part of the effort is made by gravity and your weight.

Just adjust the derailer in the front with the stop nuts and ditch the cable, so you can use your bike with a smaller sprocket. This is the poors man downhill chain guide.

byebye

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Depending on your body size, leg power, and hills in your area, you can snap chains and wrench axles out of the dropout with too much torque.

As for your legs, BIG gear ratios are a good way to get BIG leg muscles. There's a reason all those fixie punks favor cutoff jean shorts. But, as with any repetitive exercise, you can strain your knees if you're not careful.

I did this to myself, but the solution was to fiddle with the ratio a bit and listen to my body. Recently, I've been learning about the ratio of hamstring to quadriceps strength being a major factor in knee injuries- having comparatively weak quads will leave your knee unsupported.

So get some clips or powerstraps and you'll be rocking it.

  • If your bike breaks from too much power then your bike needs fixing. Putting down the hammer should not make you worry about whether the bike can take it. Good first answer, and welcome to SE. – Criggie Feb 19 '18 at 10:42
  • In general, high force on the chain and at the rear drop out mostly occurs with small chain rings, not high gear ratios. In general, extreme chain tension occurs when the chain is moving slowly while a lot of power is being put through the drive train. That combination does occur when you're first starting out from a stop, but even more so when you're starting out from a stop in the small ring. – R. Chung Feb 19 '18 at 15:52
  • A small chainring applies less force per degree rotation... As for the bike breaking, I learned quickly that you shouldn't ride SS with a quick release. – Patrick Zissou Feb 20 '18 at 1:26
  • Suppose you had a 54 tooth chainring and an 18 cog for a gear ratio of 3:1. Suppose you also had a 36 tooth chainring and a 12 cog for the same gear ratio. Suppose you were pedaling at the same cadence and with the same pedal force; then you are pedaling with the same power and moving at the same speed. Compare the chain tension in both cases. Chain tension will be higher for the smaller chainring. – R. Chung Feb 20 '18 at 6:24
  • forgive my ignorance but why would that be? if i apply force to crankarms of the same length, with different chainrings but the same ratio the wheel will still rotate the same number or degrees/apply the same force to the ground. what am i missing? – Patrick Zissou Feb 20 '18 at 6:42

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