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Discussion Starter · #1 ·
I have recently noticed that my chainrings seem to be wavy, especially the large ring. When the chain is on the large chainring, I look down and see the chain travel from the outer-side of the mech cage to the inner-side of the cage. It doesnt always rub, and I can usually trim it out if it does. There is no side-to-side play in the crankset.

I have recently started to ride a 1.5 mile crit-like loop for about 20 miles a day. It has two small rises and two area where I "sprint." I didn't notice the wave was this bad before, but maybe i am more nitpicky now. It is a cheaper Nashbar compact crankset. Is the outer chainring warped or do all chainrings wave like this? Should I just go ahead and replace the crankset with a standard crankset if I am goin to continue this loop? I have noticed a small "wave" on other cranksets, but not this much.

Anyone know anything about the Race Face Cadence crank?

Thanks in advance.
 

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I would spin the cranks and see if it still happens when you're off the bike. When you're under full pedaling load, the bottom bracket is going to flex a little from side to side, and the BB axle and chainrings can flex as well, giving the illusion of a warped chainring without it necessarily being permanently bent. You can also take the chainring off and lay it on a flat surface to be really sure (that would take a fair amount of disassembly and possibly a couple of specialized tools though)

As to why you didn't notice it before, it could be that you're getting stronger, and/or have developed a flaw in your pedaling technique so that you aren't balancing the forces as evenly between the two sides of the BB, causing more flexing.
 

· naranjito
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Even the flexiest of frames will not move enough to make the chainrings touch both the inner and outer plates of the front mech. The rings or bent, and the only thing to do is either bend them back, depending on how bad they are, or replace them.
 

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Discussion Starter · #5 ·
There is a warp to the rings. When I am in the small ring the front mech is directly over the outer teeth. As a rotate the crank, the teeth go outside the outer plate.

i may try the race face crankset...
 

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The test and the fix

weltyed said:
I have recently noticed that my chainrings seem to be wavy, especially the large ring. When the chain is on the large chainring, I look down and see the chain travel from the outer-side of the mech cage to the inner-side of the cage. It doesnt always rub, and I can usually trim it out if it does. There is no side-to-side play in the crankset.

I have recently started to ride a 1.5 mile crit-like loop for about 20 miles a day. It has two small rises and two area where I "sprint." I didn't notice the wave was this bad before, but maybe i am more nitpicky now. It is a cheaper Nashbar compact crankset. Is the outer chainring warped or do all chainrings wave like this? Should I just go ahead and replace the crankset with a standard crankset if I am goin to continue this loop? I have noticed a small "wave" on other cranksets, but not this much.

Anyone know anything about the Race Face Cadence crank?

Thanks in advance.
Assuming that your BB is OK (i.e. not loose - it's extremely unlikely that it's bent), you have to straighten your spiders and/or chain rings. If it's a CF crank, then only your chain rings can be straightened. Hold a small screwdriver or other short, pointed object against the seat tube so that the tip just grazes the crank spiders as they pass. If the spiders are bent, you can even them out as follows:

Place the bike on its side with the crank supported on a block of wood at the axle. With another block of wood or a stout dowel placed at the end of the offending spider(s) give it a whack with a hammer. Check for change in alignment. If you got no change, hit it harder next time. Repeat until all the spiders are even. You may need to bend them away from the frame (brace the right crank on the block of wood) or toward the frame (brace the left crank).

Once the spiders are even, check the chain rings with the same technique except put the point of your screwdriver at the teeth of the rings (most likely the big ring only if the spiders are even). Straighten the chain ring by placing a large adjustable wrench over the ring with the jaws adjusted for a slip fit over the ring. Bend gently, and check alignment. Repeat until you've got it right.

Even with the chain rings dead straight, you still will get some deflection due to pedaling forces, but that should greatly improve your situation.
 

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RaceFace Cadence

weltyed said:
Anyone know anything about the Race Face Cadence crank?
Can't really add to your initial question about 'wavy' chains that hasn't already been said. However, I have a pair of the Cadence cranks on my bike that I've enjoyed very much so far. I've got a Marinoni Delta Xtra that I've got them on and they feel as stiff as any other crankset I've had. They're integrated with the bottom bracket and have an external bearing setup. I've never really checked, but I believe they compare favorably with other aluminum crank setups and seem to be plenty durable after 2500 miles so far. Each time i clean them off, they look just as good as new with very few dings or nicks that I can see. If you've got a set or have a good deal pending, I don't think you'll be disappointed.

have fun,
aaron
 

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Possibilities

BikeGeek said:
If the cranks are the square taper style it is possible the taper is not perfecly concentric and the crankarm is not perfectly paralell to the bike creating a chainring wobble.
Actually, this is a possibility with any BB design. However, it is an EXTREMELY unlikely possibility, regardless of BB type.
 
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