Crankset Wobble
12-12-10 | 03:55 PM
#1
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Crankset Wobble
Over the last year I have been getting into cycling, and I recently upgraded to a used 08 Scott CR1 Pro with a SRAM force groupo. The bike shifts fine but I recently noticed that the crankset wobbles from side to side slightly (see video). What would be the fix for this (hopefully not a new crank)?
Thanks!
Thanks!
12-12-10 | 04:47 PM
#2
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Joined: Sep 2004
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From: boston, ma
grab the drive side crank and push it in/out axially, do you feel play? if yes then the crank will need to be removed, splines greased and retorqued. if their is no play then the spider is bent because i saw both chainrings moving in sync.
12-12-10 | 06:10 PM
#3
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Joined: Jun 2010
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From: NW,Oregon Coast
Bikes: 8
If there are no BB problems , then its just chain ring run-out, not perfectly flat.
I'd say ride the bike and see if it matters functionally, moving down the road,
rather than spinning the cranks and looking at them.
It may not, the run-out seems rather slight.
if it does, you may wish bend the chainring, but as you have a critical eye
to know it's right , you need machinist's dial indicators
to check your accuracy with precision feedback measurements..
I'd say ride the bike and see if it matters functionally, moving down the road,
rather than spinning the cranks and looking at them.
It may not, the run-out seems rather slight.
if it does, you may wish bend the chainring, but as you have a critical eye
to know it's right , you need machinist's dial indicators
to check your accuracy with precision feedback measurements..
Last edited by fietsbob; 12-12-10 at 06:13 PM.
12-12-10 | 06:21 PM
#4
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From: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Someone please correct me if I'm wrong here, but I believe Force cranks are carbon fibre with the right crank integrated onto the spindle. As such there's very little that can be done to straighten them.
I suggest you have a dealer familiar with force cranks give it a look, rather risk making things worse with a brute force attempt at a fix.
I suggest you have a dealer familiar with force cranks give it a look, rather risk making things worse with a brute force attempt at a fix.
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FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
12-12-10 | 07:36 PM
#5
17yrold in 64yrold body
Joined: May 2010
Posts: 922
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From: Northern CA
A close look at the video shows that it is not just the ring, but the crank itself (blue in video) that is wobbling. I would think that if FBinNY is right about it being carbon, the only fix may be replacement.
12-15-10 | 08:02 PM
#6
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Bummer. I will bring the bike to the local shop, but most likely I will need a new crank? I rode the bike a couple times and haven't had any issues with shifting, but I am worried that overtime this wobble will cause me to change the change and other components more often.
Thanks
Thanks
12-16-10 | 12:01 PM
#8
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From: A Coffin Called Earth. or Toronto, ON
Bikes: Bianchi, Miyata, Dahon, Rossin
you can tell the entire crank is wobbling by putting on a mini level onto the pedal while securely holding the bike upright.
if the level gives center at the 3' and 9' positions, but not 12' and 6' positions, then it's the entire crank.
if the level gives center at the 3' and 9' positions, but not 12' and 6' positions, then it's the entire crank.
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