What are the more common reasons for a chain throw-off ? What happened to me today was thus. Approaching lights. Slowed and stopped pedalling. At the same time geared down one level. Chain was on large ring. Did not gear down to the smaller ring. Chain popped off to the inside and wedged summat awful between BB and inner ring. This is only the second time in just over a year of riding this new ( carbon ) bike. Both times however have resulted in the same really tight wedging bewteen BB and inner ring and surface scraping to the BB area. Sure this not a good thing to happen with a carbon frame ! I believe derailleur set-up is good ( as I say, this certainly not a frequent occurence ). How do I virtually eliminate this event ? Is not continuing to pedal while down shifting the culprit here ?
Thrown Chain
- Thread starter jimbut
- Start date
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lazyfatgit
Guest
- Location
- Lawrence, NSW
is it possible you back pedalled?
its possible to jam the rear mech when moving to a lower gear, create a loose loop in the top of the chain, then it skips off when you pedal again?
never change gear without pedalling forward, unless your using hub gears.
its possible to jam the rear mech when moving to a lower gear, create a loose loop in the top of the chain, then it skips off when you pedal again?
never change gear without pedalling forward, unless your using hub gears.
Smokin Joe
Legendary Member
- Location
- Bare headed cyclist, Smoker
Fit a Dog Fang. No matter how accurate your mech is set up it is still possible to bounce your chain over the inner ring as it drops, this is why many of the pro teams use them.
Globalti
Legendary Member
I have exactly the same problem but can't fit a Dog Fang because the carbon seat tube flares out towards the BB. I have shortened the chain by one link and this has improved matters but it still drops off about 1 in every 6 or 8 changes to the small ring.
My only solution is to fit a bolt-on derailleur with separate band then there's an expensive little device that can be bolted onto one of the mounting bolts.
My only solution is to fit a bolt-on derailleur with separate band then there's an expensive little device that can be bolted onto one of the mounting bolts.
Gerry Attrick
Lincolnshire Mountain Rescue Consultant
jimbut said:
Are you absolutely certain your limit screw is adjusted correctly?
Yeah, am sure the set-up is good cos as I say, only the second occurence and my stupidity caused the first when I horlicksed fitting a new chain. Interested in this dog fang. Never heard of it. Is it some sort of catcher ? Any of the usual online places stock them ?
Gerry Attrick
Lincolnshire Mountain Rescue Consultant
That's all it takes!
Smokin Joe
Legendary Member
- Location
- Bare headed cyclist, Smoker
Check that your rear set up is as good as you think it is, check that there are no stiff links in the chain, then check that the derailler hanger is straight - if the set up is perfect the chain should always run free - never known the chain to come off at the front if the rear is right when not shifting between the front rings and certainly not when back pedalling
Smokin Joe
Legendary Member
- Location
- Bare headed cyclist, Smoker
Gerry Attrick
Lincolnshire Mountain Rescue Consultant
Tend to agree with psmiffy. I have ridden a Synapse SL for two years now and have never had a chain thrown. I recommend you set up both mechs from scratch before paying out money for accessories you probably don't need.
Gerry Attrick - r u the same guy who in essence said that a back pedalling action ( albeit probably a very slight one, amounting to a backward movement of the crank in this case ) would be a very likely cause of a chain throw. If forking out £10 or so protects against the sort of jam I experienced today, I am very happy to do so.
Gerry Attrick
Lincolnshire Mountain Rescue Consultant
Yep.....same person. It is true a reverse pedal can throw a chain, but that is down to rider error which hopefully will be eradicated by experience. Let your experience educate.
