Fixing jammed chain and geers

[chrissmit]

Hi I have a Brompton where all of a sudden the gear jammed in a really bad way.

What is the best way to go about this?

I've attached a couple of pics to show you what is going on...

 

[rafiki]

The tensioner is awry. Loosen it off to see if it will reposition correctly. If not the bolt may need replacing.

 

[chrissmit]

Hie,

Thanks for your reply. The "tensioner is that plastic with the two little gears, right?

 

[Chris S]

Hie,

Thanks for your reply. The "tensioner is that plastic with the two little gears, right?

Yes - pulley wheels would be a better description. The chain has come off them.

 

[chrissmit]

So, what do I do best:
Remove that "pulley wheel"/ "Tension awry" or remove the chain first (using a special tool that I have)?
Or take out the whole back/reat wheel and see what happens?

Thanks

 

[Kell]

Was it all working correctly before this - or has someone been fiddling?

Because from what I can see there's no way the chain should be that side of the bolt holding the jockey wheel in place for the chain pusher. If correctly fitted, it shouldn't be able to jump out between the chain pusher and the guard rails on the jockey wheel.

 

[Kell]

If you have a look at this, you'll see how the chain path should be on a 2/6 speed with the chain pusher.

View: https://youtu.be/6PKu0fJ5c0w?t=236

 

[Chris S]

Or you could try just putting the chain back on the pulley wheels first. You should be able to raise the end of the tensioner with your finger to get the chain back on. If you can't then there's a problem with the tensioner.

 

[T4tomo]

the tensioner has somehow flipped 180^ plus from where it should be. The bolt holding it on place may be loose , or it make be photo angle playing tricks, but it looks out of wonk on the 2nd photo, which may be how it was able to flip back?

 

[chrissmit]

Or you could try just putting the chain back on the pulley wheels first. You should be able to raise the end of the tensioner with your finger to get the chain back on. If you can't then there's a problem with the tensioner.

The chain is as tight as a ***; can't move it an inch/mm

 

[chrissmit]

I'll turn this into a project for tomorrow.

Thank you all for the help so far.
I'll keep you posted!

 

[Kell]

The chain is as tight as a ***; can't move it an inch/mm

Ordinarily, I'd say swing the back end down as that releases the tension on the chain (hence the need for the chain tensioner in the first place). Have you already done that? It's hard to see from your pics, but I'm assuming you have as your luggage rack is on the floor.

The chains do have a breaker link in though - but you might need some chain pliers to remove it.

Wiggle | Park Tool Master Link Pliers MLP-1.2 | Chain Tools

I'm still genuinely confused though as to how you managed to get the tensioner underneath the chain that should be going over the top of your rear sprockets.

 

[T4tomo]

I always found when arsing around with the back wheel on a brommie, laid on its side on the floor was its best position, then you could fold its back wheel into the foetal position to relax it / release chain tension.

 

[Ming the Merciless]

Undo the gear cable then undo the hex bolt. That will enable you to take the chain tensioner etc off , and free up the chain. Then put it back together in right position.

 

[chrissmit]

Undo the gear cable then undo the hex bolt. That will enable you to take the chain tensioner etc off , and free up the chain. Then put it back together in right position.

I just undid the chain. I had a look at the chain tensioner and when I align it with the other fixed little gear, they are not. I also think I can visible see that part of that tensioner is damaged.
I'll go to a dealer and ask him and possibly get it replaced.