Jammed Chain

borderraider

Hello all

I wonder if anybody can help. Whilst out riding last night my chain has become jammed between the bottom bracket and the smallest chainring (it's a triple). I have spent a fair while trying to release it but to no avail. Does anybody have any ideas / tips as to how I may get it out and if not is my best option to:

A) Break the chain, remove it and refit (the chain is not a quick release type.)

Remove the crank (the bike is a Trek Alpha 1.2, with FSA cranks, I think it is a square type spindle but I am not sure.)

Any help greatly appreciated.

Shaun

Dmak

Brute force got it in there, brute force can get it out. This happened to me when I stacked it into a roundabout.

If you've got the tools to remove the crank, that's probably the wiser option.

borderraider

To be fair I think I've given 'brute force a fair old go!!

Does anybody know what type of crank (i.e square, splined etc) this bike is most likely to have, I have had a fair google round the subject by cannot be certain.

Shaun

Dmak

Fair enough, looks to be square taper. Should be able to pick up the right tool from your LBS, just be very careful using it because if you don't get the tool into the crank enough you strip the internal thread and then you're completely buggered.

I would probably work out cheaper to just get your LBS to sort it, unless you want the tool for future maintenance.

borderraider

Thanks Dmak

I usually like to have a crack at things myself, but don't like the idea of stripping the internal thread, plus I want it back on the road ASAP, so might just drop it into the LBS at lunch.

If anybody else has any ideas of how to release the train without removing the crank, I'd be grateful to hear.

Thanks

Shaun

pdstsp

This happened on my old bike and it was actually the end of the chain ring bolts which stopped the chain from coming out of the gap. By removing one or two of the bolts (the ones attaching the inner chainring to the rest of the crankset) it was possible to remove the chain from the gap - pain in the arse but easier than removing a crank on the side of the road

keef66

Removing the crank is the simplest solution, but you need to be sure what type of BB you have. If it's square taper and the cranks are secured by simple bolts, make sure you remove the washer along with the bolt, and screw the crank extractor all the way in to the crank before trying to tighten the inner bolt to pull the crank off.

If it's a self extracting type crank bolt, it's even easier.

Look on Park tools or Sheldon Brown's websites for pictorial guidance

rolf_f

Surely the simplest solution is just to split the chain! You'll have to do it sometime or you'll prematurely wear the chainrings out.

keef66

Splitting the chain won't help to free it if it's securely jammed twixt chainring and BB. I once spent half an hour with a lump hammer and a cold chisel trying to dislodge a very jammed chain on a mountain bike. Destroyed the chain and didn't do the frame any favours.

Popping the crank off will be a lot easier.

(Wasn't an option for me due to an earlier bodged attempt at crank removal; - removed the bolt but left the washer in so the crank extractor stripped the internal threads from the crank)

rolf_f

keef66 wrote:

Splitting the chain won't help to free it if it's securely jammed twixt chainring and BB. I once spent half an hour with a lump hammer and a cold chisel trying to dislodge a very jammed chain on a mountain bike. Destroyed the chain and didn't do the frame any favours.

Popping the crank off will be a lot easier.

(Wasn't an option for me due to an earlier bodged attempt at crank removal; - removed the bolt but left the washer in so the crank extractor stripped the internal threads from the crank)

OP suggested splitting the chain as an option so I assume it isn't jammed - rather just trapped.

keef66

The second post of "To be fair I think I've given 'brute force a fair old go!!" suggested to me that it was securely jammed in there.

rolf_f

Well, he's got some suggestions!

borderraider

Thanks for the help guys.

Didn't want to split the chain as I was afraid of weakening it.

Popped into my friendly LBS, 'The Bike Shop' in Pinner to buy the relevant tool and they offered to do it for me for free.

Top marks to them!!

keef66

Top marks to them indeed!