chain slipping off while towing

[alecstilleyedye]

i've had my chain slip off onto the bb twice today while towing my 5 year old son in the burley trailer. i went to pick him up from my parents' with the trailer empty and no problems, but once the weight of a 5 year old was added, i twice had the chain off. it's not the limit screws or the position of the mech, as i've fiddled with both to get it running fine tow-free.

it's a 531 steel frame (winter bike in sig line); could it be flexing under load to affect the chain line? or is it a problem that could be cured with a new chain and cassette?

cheers in advance

 

[steve52]

sounds like worn casset and chaine to me, it can be checked by someone who is in the know lbs or another cyclist near you

 

[RecordAceFromNew]

i've had my chain slip off onto the bb twice today while towing my 5 year old son in the burley trailer. i went to pick him up from my parents' with the trailer empty and no problems, but once the weight of a 5 year old was added, i twice had the chain off. it's not the limit screws or the position of the mech, as i've fiddled with both to get it running fine tow-free.

it's a 531 steel frame (winter bike in sig line); could it be flexing under load to affect the chain line? or is it a problem that could be cured with a new chain and cassette?

cheers in advance

Assuming in all instances the chain slipped off the inner front ring onto the bb while changing gear, and assuming that the L limit screw on the front mech is set so that there is only a 1mm clearance between the mech and the chain when it is on small front large rear, then it could be just due to changing under load - which can happen even with a brand new drivetrain, and is because changing under load is at best agricultural for any front derailleur system. As you know, ideally the front change should be executed when there is little pressure on the pedals, but of course that is easier said than done all the time.

A simple cure for that could be just get a Dog Fang or copy. They come in different size to match the seat tube diameter.