Numpty gear compatibility and chain length question

[Psycolist]

Surprised nobody has mentioned the chain line, In my limited experience, a bad chain line can cause these symptons.

 

[srw]

Surprised nobody has mentioned the chain line, In my limited experience, a bad chain line can cause these symptons.

The one thing I've focussed on most is the chainline - because it's the easiest to control. The Revoshift shifters have the barrel adjuster at the handlebars, so I can play around while I'm riding, as well as when I'm stopped.

 

[srw]

For new chains, I found a how-to that said largest ring to largest sprocket, tight length plus two links plus quicklink. So far it seems to work.

"Tight length" as in "Derailleur just about as extended as it will go"?

 

[Cubist]

"Tight length" as in "Derailleur just about as extended as it will go"?

No, wrap the chain around the largest two rings without going through the mech. You're looking for tight at that and then add a couple of links. However, with respect to TMN, the two links will include the quick link. As in one side plate half link, two inner links and the quick link.

A couple of things to check ngiven your symptoms, is that the chain is not too long. If it is, the rear mech folds against itself. Check B tension adjustment.

 

[Cubist]

There are occasions where two additional links can be too long, but I doubt it in this scenario. It will simply be that the chain is a few links too long out of the box, and needs cutting. The rear mech can't function in the smaller chainring because there's no tension in the mech and the chain will be fouling itself as it runs over itself through the jockeys.

 

[srw]

No, wrap the chain around the largest two rings without going through the mech. You're looking for tight at that and then add a couple of links. However, with respect to TMN, the two links will include the quick link. As in one side plate half link, two inner links and the quick link.

A couple of things to check ngiven your symptoms, is that the chain is not too long. If it is, the rear mech folds against itself. Check B tension adjustment.

Ah - thanks. That's helpful. But (you can tell I'm an experimenter not a mechanic, can't you) - what is B tension adjustment?

 

[Dogtrousers]

The B screw is the 3rd adjustment screw on your rear mech (after the hi and lo limit screws). It positions your mech nearer or further from the cassette

 

[srw]

There are occasions where two additional links can be too long, but I doubt it in this scenario. It will simply be that the chain is a few links too long out of the box, and needs cutting. The rear mech can't function in the smaller chainring because there's no tension in the mech and the chain will be fouling itself as it runs over itself through the jockeys.

Whether this was the specific problem, shortening the chain to the length suggested by TMN helped.

Of course it might have helped even more if the bit of the chain I excised to shorten it wasn't the bit that includes the quicklink - but I now have a functional chain and what appears to be a functioning derailleur system.