Chain tension inconsistent
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Chain tension inconsistent
I know that cranks aren't perfectly round and as the crank turns the tension on the chain changes but it seems like on my bike that the change is considerable. When the drive side arm is parallel to the ground and pointing towards the front of the bike, the chain tension is good. When the same arm points to the rear the chain sags almost an inch. Is this much of a difference normal or is something up?
#3
aka mattio
what kind of crank and ring do you have? some are rounder than others.
this phenomenon bothered me a whole lot more riding on the street than on the track.
this phenomenon bothered me a whole lot more riding on the street than on the track.
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Unless it's a biopace ring, that sounds a bit too much/messed up - check out your ring center-ness as Jenkinsal2 said.
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I know that cranks aren't perfectly round and as the crank turns the tension on the chain changes but it seems like on my bike that the change is considerable. When the drive side arm is parallel to the ground and pointing towards the front of the bike, the chain tension is good. When the same arm points to the rear the chain sags almost an inch. Is this much of a difference normal or is something up?
#10
aka mattio
i've never played around with miche advanced but it's a high quality enough ring that this *shouldn't* be a problem. definitely try recentering your chainring via sheldon's method.
#11
Prefers Cicero
For those who don't click the link, Biopace chain rings are slightly oval, to try to even out power distribution around the pedal stroke. If you look down as you ride you will see the front of the chainring seem to move forward and back with each stroke.
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Re clock the chain ring in a different position. How many bolts does it have? That's how many possible positions it has. Maybe one position is more centered then the rest?
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I thought about that but like na975 posted above, the chainring and spider are machined to fit perfectly. There is no wiggle room. If something is off, no matter what position it's at it will be the same.
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cog cross-threaded? stiff link in your chain?
#20
aka mattio
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#22
Prefers Cicero
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I hope my Phil Wood hub wasn't poorly built. I'll check the links to see if there is a stiff one. I also try rotation the chainring to see if that does anything.
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While you have your chainring off, use a compass to go around the half of the chainring with the arm forward (the half that the chain is engaged on). Then do the same with the arm facing back. A lesser number will tell you that the ring is the problem.
I had thought about using a diameter measurement, but it doesn't seem to work right in my head. I think an arc measurement would be better. If you can't measure the arc properly (get a length figure), then do the longer one first (arm forward) and attempt to 'overlay' the same arc with the loose side (arm backward) - if they're not on top of each other, or even close, you know it's the ring.
I had thought about using a diameter measurement, but it doesn't seem to work right in my head. I think an arc measurement would be better. If you can't measure the arc properly (get a length figure), then do the longer one first (arm forward) and attempt to 'overlay' the same arc with the loose side (arm backward) - if they're not on top of each other, or even close, you know it's the ring.
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If it's not too big of a problem, you can simply loosen the tension on the chain to compensate. It doesn't take care of the problem but it makes it unnoticeable.