Horrible evil tandem chain..

I need some help folks.
I just nearly hurled my tandem into a ditch, and then had to push the stupid thing home again. Why?

Because the chain came off. :ohmy: Am so angry because chains are a piece of p*ss to sort normally..not something that bothers me. But this one..:angry:

It came off in the middle chainring - the double one which connects front and back chains. So should have been a case of just whipping it back on. But the inner ring is so close to the frame that there is no room for the chain to pass unless its on the ring, which of course it's not. Everytime I tried to wind it round it just got jammed between chainring and frame.
I tried it every which way and I cannot get it on.

What am I missing folks? Is this a common thing with tandem chainrings, or just with mine? :wacko:
At the moment the only way I can see to fix it is to split the chain and thread it through that way, but I've never done that in my life so am a bit scared. Do have a chain thingy tool though..

Hopefully, I'm just being thick and someone can point out the obvious to me.

Thanks people..
 

NickM

Veteran
I am struggling to understand "It came off in the middle chainring - the double one which connects front and back chains". Does the chain which connects front and rear chainsets run down the right hand side of the bike? Does the connecting chain use the innermost (small) chainring at the back? How many chainrings are available for gear changes at the back?

One thing very well worth having on the drive side of tandem chainsets is this:

http://www.sjscycles.co.uk/product-Sugino-Sugino-Autex-One-Key-release-crank-bolts-265.htm

They get you out of the kind of jam you have described with just a 6mm Allen key.

Another useful device, which may be applicable to your problem:

http://www.gvtc.com/~ngear/whatis.html

Necessary on aluminium tandem frames, I would say.
 
OP
badkitty

badkitty

A Fiddler of ill repute
NickM said:
I am struggling to understand "It came off in the middle chainring - the double one which connects front and back chains".Sorry..was still cross..:angry::blush: Does the chain which connects front and rear chainsets run down the right hand side of the bike? YesDoes the connecting chain use the innermost (small) chainring at the back?Yes - the one powered by me at the front is on the smaller part (inner) of the double ring that we share, so sprogs chain is on the bigger (outside) ring and then runs to the internal gear sprocket behind her. How many chainrings are available for gear changes at the back?Internal gears, so just the one.

Does that make it any clearer? I think I might go and take a picture of it, because I'm not doing a great job of describing it, am I? :wacko:

One thing very well worth having on the drive side of tandem chainsets is this:

http://www.sjscycles.co.uk/product-Sugino-Sugino-Autex-One-Key-release-crank-bolts-265.htm

They get you out of the kind of jam you have described with just a 6mm Allen key. Erm..still in thick mode...so would that allow me to just slaken off the cranks, and wiggle the chain ring out a bit to get the chain past?

Another useful device, which may be applicable to your problem:

http://www.gvtc.com/~ngear/whatis.html

Necessary on aluminium tandem frames, I would say.And i would agree!:ohmy:


Thanks for your help nick - is most appreciated.
 

NickM

Veteran
"...would that allow me to just slaken off the cranks, and wiggle the chain ring out a bit to get the chain past?"

Yes! It does nothing to explain why the chain is coming off, though... I think pictures might be needed to solve that. I suspect, though, that whatever device you have to maintain tension in the connecting chain is not maintaining enough tension.

Do you Does your tandem have an eccentric bottom bracket (oooer, missus!) ?

If you are using a hub gear, the Jump Stop may be superfluous.

PS Ah, I think a visualisation is taking shape :angry:

The connecting chain comes off at the stoker's chainset and gets jammed somwhere down around the stoker's bottom bracket, yes? This does sound like insufficient tension in the connecting chain. If that is something you are not equipped to sort out, a front derailleur (any old cheap one) fitted on the stoker's seat tube, with no cable connected to it but with the travel limit stops adjusted to position its cage over the chainring, may solve the problem for the time being.
 
OP
badkitty

badkitty

A Fiddler of ill repute
NickM said:
"...would that allow me to just slaken off the cranks, and wiggle the chain ring out a bit to get the chain past?"

Yes! It does nothing to explain why the chain is coming off, though..Ah...I can help with that particular mystery...Twas a stick..a big one. .bit of an occupational hazard riding through woods all the time. Never been this much of a nuisance before though. Even twiggy birch sticks have failed to stop me, even when wrapped twice around rings. Took a while though. :becool: I think pictures might be needed to solve that. I suspect, though, that whatever device you have to maintain tension in the connecting chain is not maintaining enough tension.

Do you Does your tandem have an eccentric bottom bracket (oooer, missus!) ? :angry::rofl::wacko: tbh, i'd be surprised if it didn't!:biggrin:

If you are using a hub gear, the Jump Stop may be superfluous.

PS Ah, I think a visualisation is taking shape :smile:

The connecting chain comes off at the stoker's chainset and gets jammed somwhere down around the stoker's bottom bracket, yes? This does sound like insufficient tension in the connecting chain. If that is something you are not equipped to sort out, a front derailleur (any old cheap one) fitted on the stoker's seat tube, with no cable connected to it but with the travel limit stops adjusted to position its cage over the chainring, may solve the problem for the time being.
I could also pay more attention to what I'm riding over too, couldn't I? :ohmy:


So am I right in thinking that there are only two ways to sort this - one being to split the chain, the other being to loosen off the chainring?
And that jumping up and down and swearing at it some more really won't fix it?


I'm just sorting the pics, but I'm not sure how helpful they're going to be.


Ta!
 

summerdays

Cycling in the sun
Location
Bristol
badkitty said:
And that jumping up and down and swearing at it some more really won't fix it?
I have tried that method before and so far scientifically I would have to say my results would seem to indicate your conclusion was correct:biggrin:.
 
OP
badkitty

badkitty

A Fiddler of ill repute
Ok, so this is the problem viewed from above.The chain is one the teeth nearest the camera, but then gets snarled up on the frame as the pedal's turned.



GEDC0368.jpg








And here is the ring from the front..


GEDC0367.jpg


so erm. do i need to prise off the plastic bit in the middle in order to loosen it? :angry::blush:
And how easy is it to get it back on afterwards? :wacko:

 
OP
badkitty

badkitty

A Fiddler of ill repute
summerdays said:
I have tried that method before and so far scientifically I would have to say my results would seem to indicate your conclusion was correct:biggrin:.
Bah! maybe our sample thus far hasn't been big enough though? I'm willing to give it one more try. Care to join me, Summerdays? :wacko:

Another thought - maybe we just didn't shout loud enough, or use the right swearwords? These factors are important, you know...:angry:
 
OP
badkitty

badkitty

A Fiddler of ill repute
ASC1951 said:
Not sure about unjamming it, but you may have a chainsuck problem even if tension is correct. Is your chainring worn?

It doesn't look worn. Erm..forgive me, but what exactly is "chainsuck"? I probably need to know that. :thumbsup:

Anyway have decided that the real problem here was that I was being a wuss and trying to avoid the obvious solution - splitting the chain.
So I summoned all my courage and took it off.The chain is now soaking in degreaser. :smile:
I know that's apparently the easy bit, but I'm hopeful. The metal bit's still in the chain, so it might go back on. :biggrin:
 

summerdays

Cycling in the sun
Location
Bristol
badkitty said:
Bah! maybe our sample thus far hasn't been big enough though? I'm willing to give it one more try. Care to join me, Summerdays? :biggrin:

Another thought - maybe we just didn't shout loud enough, or use the right swearwords? These factors are important, you know...:smile:
I'm sure there will be more occasions when I try the talking/shouting at the bike in order to persuade it to work.... I'm just not convinced of a high sucess rate... still you could be right - I might not be using the correct words:biggrin:.

badkitty said:
It doesn't look worn. Erm..forgive me, but what exactly is "chainsuck"? I probably need to know that. :thumbsup:

Anyway have decided that the real problem here was that I was being a wuss and trying to avoid the obvious solution - splitting the chain.
So I summoned all my courage and took it off.The chain is now soaking in degreaser. :biggrin:
I know that's apparently the easy bit, but I'm hopeful. The metal bit's still in the chain, so it might go back on. :biggrin:
OK chain suck I know a little about ... my first bike suffered very badly with it from about 4 weeks after purchase until strangely a new chain seems to have sorted most of the problem out. It's where the chain doesn't leave the front rings and going to the back and instead gets pulled up and quite often trapped between the bottom stay and the rings - jammed tight. It got to the point that I could recognise the sensation and stop pedalling immediately before it jammed solid.

I'm not going to go into the causes of chain suck... I never managed to fully understand it.

And if this is going to be a regular occurrence (hopefully not) can I recommend the Sram chains that have that joining link on them.. makes it really easy to undo the chain.
 
OP
badkitty

badkitty

A Fiddler of ill repute
Crackle said:
You might want to soak the rest of the poor beast in soapy water while you're at it, judging by the BB :thumbsup:
You think?

That is clean! I'll have you know that when I chipped apart a big brown bike shaped boulder last week, that was what I found inside! Which is a vast improvement.
So don't come here with yer scary one-eyed cleanliness fascism..:biggrin:::smile:

But in case it matters, that chain is beautiful now.:biggrin:
 
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