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A bent crank would be really unusual. Are you sure he didn't say the chainring was bent? Does the chain rub the derailleur constantly or is it only at a certainly place in the pedal stroke?
A bent crank would be really unusual. Are you sure he didn't say the chainring was bent? Does the chain rub the derailleur constantly or is it only at a certainly place in the pedal stroke?
It rubs it constantly when in the two cogs closest to the wheel.
If it's constant it doesn't sound like a bent chainring or crank.
I don't know what to think now. When I was in the store he showed me how my chain wasn't in a straight line from the rear to the front. If it isn't a bent crank, do you know what it might be? A bad BB?
If the chain rubs throughout the entire pedal revolution, then either:
a) The front derailleur needs to be adjusted.
b) The bottom bracket spindle is too wide.
c) Something is seriously wrong with the frame (which would probably be very obvious, though).
It sounds like he was just pointing out the chainline, unless I'm misunderstanding. Just to clarify, are you saying the chain rubs the front derailleur when it's on the small chainring up front, and the large cog in the rear (which would be the bike's lowest gear)?
Edit: It kind of sounds like the guy was pointing out that you're cross-chaining, which is when you have the chain in the big ring up front and one of the larger cogs in the rear (or vice-versa). That could definitely make the chain rub, but it's an easy fix since all you'd have to do is shift to one of the smaller rings in the front.
If the chain rubs throughout the entire pedal revolution, then either:
a) The front derailleur needs to be adjusted.
b) The bottom bracket spindle is too wide.
c) Something is seriously wrong with the frame (which would probably be very obvious, though).
It sounds like he was just pointing out the chainline, unless I'm misunderstanding. Just to clarify, are you saying the chain rubs the front derailleur when it's on the small chainring up front, and the large cog in the rear (which would be the bike's lowest gear)?
Edit: It kind of sounds like the guy was pointing out that you're cross-chaining, which is when you have the chain in the big ring up front and one of the larger cogs in the rear (or vice-versa). That could definitely make the chain rub, but it's an easy fix since all you'd have to do is shift to one of the smaller rings in the front.
At first he was talking to me like I was cross chaining, but I know not to do that after reading about it. I then informed him that it rubs in the lowest gear (small-front large-rear) and then he could see it was rubbing. It then went on to tell me that it was just going to rub in those two gears (which I was thinking was just BS that he was feeding me) then I saw him looking at it like something was wrong and then he said it was crooked or bent and I asked what was and he said my crank. That is when he had me look from behind again and he pointed out how instead of running in a straight line, the chain was on an angle. It was not as severe as it would be if it was cross chaining, but it wasn't straight. He adjusted the limiter and it was still doing it. He then fixed some of the bent sections in my large ring with a hammer (just some small bends). He asked me what kind of riding I will be doing and he then said that it wouldn't be that big of a deal because I wouldn't really need those gears and would be fine just avoiding them. He said that I should probably just avoid the small chain ring all together, probably since it only works in on gear without rubbing(without cross-chaining of course).
Hmm, that is definitely strange. I can't imagine a bent crank would cause it to rub throughout the entire revolution. It's possible the front derailleur design doesn't allow the cage to move far enough inward, but that would be some shoddy component spec work on the part of the bike company. I forgot to ask, which side of the derailleur cage does the chain rub, left or right? I just assumed it was the left.
Hmm, that is definitely strange. I can't imagine a bent crank would cause it to rub throughout the entire revolution. It's possible the front derailleur design doesn't allow the cage to move far enough inward, but that would be some shoddy component spec work on the part of the bike company. I forgot to ask, which side of the derailleur cage does the chain rub, left or right? I just assumed it was the left.
If the guy at the bike shop tried the limit screw, then I'm leaning toward the cable just not having enough slack. On the other hand, any fairly competent bike shop employee should have checked that, too. I'd either check the cable slack the way I mentioned before, or ask the bike shop to do it. Another thing, you might want to check the clearance between the smallest chainring and the chainstay. If there's a pretty wide gap, it's possible a previous owner replaced the bottom bracket with one that has too long a spindle, which would place the cranks farther from the frame that the original. That doesn't seem terribly likely, but it's the only other thing I can think of. That would still be a fairly easy fix (though probably a job best left to the shop), and cheaper than replacing the entire crankset.
I was out riding last week and I was going down a hill and all of a sudden my bars rotated forward. I almost went over the bar. I thought that it was tight enough, but I guess I was wrong. I plan on taking pictures of the crank and posting them on here. For the time being, I have just avoided that chain ring.
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