"Tosspot" <
[email protected]> wrote in message
news:
[email protected]...
> Much as a twist grip lends itself to a Rohloff hub, I'd like to try some
> sort of under bar lever system.
>
> Ideally something like the rapid fire system, but since the indexer is in
> the hub this is obviously not on, however, there must be a way using
> friction shifters.
>
> Anyone got any ideas?
In a derailleur system, the shift cable pulls the shifter parallelogram
one direction. When the cable is slackened a spring in the
derailleur pulls the parallelogram back the other way.
Rohloff shift cables work entirely differently. There are two cables.
One cable pulls one direction and the other pulls the other direction.
Think of a cable wrapped around a pulley - you pull on one end of
the cable and simultaneously let out the other end of the cable
to move the pulley one direction and reverse the process to move
the pulley the other direction.
Shifters for derailleurs only need to pull or slacken one cable.
A Rohloff shifter must simultaneously pull on one cable while
letting out slack in the other cable. You won't be able to do this
with any shifter designed for a derailleur. You will have to use
the one supplied by Rohloff or design and machine one entirely
on your own.
BobT