Chain drop during Sprint

Discuss light weight issues concerning road bikes & parts.
vanillaflyweight
Posts: 31
Joined: Thu Aug 10, 2017 5:54 am

by vanillaflyweight

I had something similar happen to me recently and the only thing I could put it down to was a change in chain lube to rock n roll gold.....which you are using...

I experienced chain suck while sprinting which stopped me pedaling very abruptly and threw me off the bike at speed.

Never had chain suck before trying RnR and haven't had it since. Probably have tried 20 other lubes.

by Weenie


TobinHatesYou
Posts: 3337
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Definitely check the Ring Drive mechanism for chipped teeth. If even one of them broke and the broken piece got stuck in the mechanism it could have prevented meshing. One reason I’m still a fan of redundant spring loaded pawls and ratchet rings.
Last edited by TobinHatesYou on Mon Nov 12, 2018 10:23 am, edited 1 time in total.

Kumppa
Posts: 274
Joined: Mon Oct 13, 2014 10:05 am

by Kumppa

This sounds like same as my case and I doupt faulty C-bear BB. Iam not mechanic but could your BB cause chain drop if it move little bit and its not totally straight assembled becouse of tolerances?

My case:
Everything was working fine with Red bb30 crankset, Sram BB (some creaking noise) and Praxis rings. Changed to gxp Dzero, C-bear BB30-GXP BB and almost new Rotor noQ chainrings and problems started.

1. first chainsuck without any reason on slow speed. Mechanic checked derailleurs and chainrings -> everything fine and probably bad luck.
2. started to hear creaking and there was resistance on cranks. Wave washer came off with 2 pieces -> probably faulty wave washer and thats why I got chain suck earlier becouse of lateral movement. Tested derailleurs if they could couse any fail even chainging both derailleurs same time, nothing.
3. Second chainsuck like first one. Another good mechanic checked BB, crank, chainrings, cassette, derailleurs and did test ride to try find any problem. Didn't find nothing. I took crank off every ~100km and checked wave washer for any marks of stress.
4. Started hear creaking while indoor riding and stopped instantly. Second broken wave washes and this time driveside BB cup have came off and rotated.

Bike still waiting to be fixed but mechanic told me there could be option to try that same C-bear BB without wave washer as he got BB386 C-bear set without washer in box and for threaded BB it's not required. Or I'll just get another BB. Newer C-bears don't even spin so good as old ones so maybe they are not so good anymore. Also switching back to Praxis rings even I think Rotor noQ works better.

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Alexandrumarian
Posts: 342
Joined: Mon Mar 28, 2016 6:34 pm
Location: Romania

by Alexandrumarian

Smth remotely similar happened to me recently. I was coasting a straight steep downhill. I noticed speed was 65-67 so I decided to push it a bit to hit 70. I did not jump on it just started to spin very fast (50-11) at which point the chain went out right side. Nothing bad happened because I felt it immmediately and stopped spinning, lost some speed, rotated some more and chain returned home. Didn't find any damage to the shifter (carbon cage) even if outer limit is tight, I imagine it could have seen some serious bending for the chain to go out. I actualy splayed permanently two cages in other situations - so better check yours too. The only thing I can think of is the worn chain (3500Km), swapped it soon after. Evrything is Campy, nasty 405 stay.

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