I recently had a JCOB 150mm carbon one crankset put on at my LBS. Bottom Bracket and everything was matched up correctly. After riding I noticed chainring wobble and is particularly noticeable in when I am in the big ring. I took it back to the LBS and they recommended to contact JCOB before the option of trying to hammer the chainring back in alignment. I am waiting to hear back from JCOB. I am wandering what my options are to fix this should it happen again? Is this a common issue with low production non Shimano cranksets and parts. I never had an issue with my shimano cranksets but am 5’5" and 150’s or 155s are much better on my hips and aero position. I beleive Shimano makes 160 or 165 at the smallest.
“Chainring” wobble can come from a bunch of different places. The chainrings can be bent. The thickness of the chainring can be off/inconsistent at the mounting point. The mounting tabs on the spider can be bent, off, or of inconsistent thickness. The spindle (if it’s a crank with a permanent spindle attached) can be off. If it’s a crank without a permanent spindle attached or attached on the non-drive side, the spindle interface can be badly broached. All of these things will basically look like a wobbly chainring.
In none of these cases is the solution to hammer the chainring back into alignment. Especially with a new crankset.
How bad is the wobble? There is an “acceptable” margin of runout in the spec for every manufacturer, and with a new crank if it’s far enough out JCOB should take care of you on this.
The wobble is significant and changing gears in the big ring is worse than small ring.
Crankset was over 600 dollars. I hope this can be resolved. Seems like Shimano might not want to make smaller cranks because of these issues.
The (Cobb)chain rings suck , they flex.
Smaller cranks from shimano is not the chain rings it’s re- tooling to go shorter.
Shimano is not interested in short cranks for the tri fits , their money is oem .
I recently had a JCOB 150mm carbon one crankset put on at my LBS. Bottom Bracket and everything was matched up correctly. After riding I noticed chainring wobble and is particularly noticeable in when I am in the big ring. I took it back to the LBS and they recommended to contact JCOB before the option of trying to hammer the chainring back in alignment. I am waiting to hear back from JCOB. I am wandering what my options are to fix this should it happen again? Is this a common issue with low production non Shimano cranksets and parts. I never had an issue with my shimano cranksets but am 5’5" and 150’s or 155s are much better on my hips and aero position. I beleive Shimano makes 160 or 165 at the smallest.
BB / Crankset Installation error?
(if the installer recommends to ‘hammer it back’ into alignment).
If both wobble, and the larger one more, I’d first exclude that.
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Does Praxis Chainrings work with the Cobb Carbon One Crankset? Since they are aluminum rings vs Carbon. I also noticed the flex on the chainring and didnt know if this was normal. Feel like I am being ghosted by JCobb since it has been 2 days of no response since I told them my problem and my LBS mechanic explanation. And the rep said they would review the issue with the team after I emailed them with photos.
Sorry for the novice question I am mechanically challenged
Yes exactly they are. Any ideas on how to remedy. The bike shop doesnt want to work on it because they want to avoid liability and JCobb hasnt got back to me.
I’d give the manufacturer a bit more time to get back to you before attempting anything yourself. 2 days probably seems like a long time to you, but given the state of the bike industry right now It’s really not in the “ghosting you” category, not by a long shot.
There simply won’t be an easy do it yourself fix for this. By far your best bet is going to be a solution from the manufacturer.
FWIW, I’m with your bike shop. If I was your mechanic, I wouldn’t work on this either. As you have described it, this is a warranty situation, not a repair situation.