Chainline

Hi
I saw on the forum a few weeks ago some kind of front derailleur that wasn't a derailleur. It was something that kept the chain on the crankset even if the line wasn't perfect. I have trawled the forum for about an hour, looking everywhere but i haven't been able to find it. Anyone remember it, or just know of something that performs this function?
Thanks
Archie

it's called a seat tube chain guide

One of these?

Deda Dog Fang

£45 for a glorified piece of plastic. Might just get dérailleur and muck about with it...

Euh, £5.95 actually.

Eh, it's £5.95.

Nice edit.

And you sir.

A dog fang is useless for keeping the chain on a single ring, since it only looks after one side, by design. It's made to stop the chain going past the inner ring on a double when you downshift. What you need is a Rohloff chain guide, which is indeed £45-£50. If you don't need the extensive chainline adjustment the Rohloff provides, you can just use a cheap front dérailleur with the limit screws holding it fixed in the desired position.

In the olden days, Campag made their 1029 model and there was at least one other similar product I recall from the 1970s, possibly TA, and now there is a seat tube mounted version of the MRP 1.X