Re: Nexus cable pull and shifter options.
Bret Wade
> The shifter is not part of the deal, though.
>
> Standard shifter is either a twist-grip or a rapid-fire type. Is
> there any chance that an STI shifter would pull the right amount of
> cable? > How much pull is needed per shift, anyway?
>
> --
>
> David L. Johnson
I'm following up on an old thread, not to continue the discussion but
for the benefit of anyone googling for a solution to the question of
whether it's possible to adapt a Shimano 9sp shifter to a Nexus 7sp
internal gear hub. It is.
I measured the cable pull of the two systems and found that the ratio of
the Nexus/9sp systems was slightly greater than 2:1 (Unfortunately, I've
lost track of the measurements so I can only describe them from memory
in general terms). I had a spare Travel Agent brake cable adapter on
hand and measured the circumference of the two diameters and found that
the ratio was slightly less that 2:1. Doing the math I found that
running a SH 9sp shift cable through a Travel Agent would come very
close to a producing a Nexus cable pull.
I've built a bike with this setup and it works very well. I used a 9sp
barend shifter with a travel agent and an inline barrel adjuster. I was
prepared to modify the Travel Agent ratio with a layer of masking tape
and/or filing, but found it wasn't necessary. Here's a picture of the
resulting bike:
http://www.fischer-wade.homelinux.org/bici/
You can find the Travel Agent here:
http://www.excelsports.com/new.asp?page=8&description=Travel+Agent+%2Dea%2E+with+adjuster&vendorCode=PS&major=6&minor=8
Cheers,
Bret
Bruce Lange
Do any of the Shimano Nexus experts out there see any problem with this?
Would it harm the hub in any way?
I really like this idea and would love to give it a shot.
Thanks for sharing Bret.
-Bruce-
David L. Johnson
> > I just found a Shimano Nexus 7-speed hub at the Trexlertown swap meet.
> > The shifter is not part of the deal, though.
> >
> > Standard shifter is either a twist-grip or a rapid-fire type. Is
> > there any chance that an STI shifter would pull the right amount of
> > cable? > How much pull is needed per shift, anyway?
> I'm following up on an old thread, not to continue the discussion but
> for the benefit of anyone googling for a solution to the question of
> whether it's possible to adapt a Shimano 9sp shifter to a Nexus 7sp
> internal gear hub. It is.
>
> I measured the cable pull of the two systems and found that the ratio of
> the Nexus/9sp systems was slightly greater than 2:1 (Unfortunately, I've
> lost track of the measurements so I can only describe them from memory
> in general terms). I had a spare Travel Agent brake cable adapter on
> hand and measured the circumference of the two diameters and found that
> the ratio was slightly less that 2:1. Doing the math I found that
> running a SH 9sp shift cable through a Travel Agent would come very
> close to a producing a Nexus cable pull.
I was idly wondering whether something like this could be made to work. I
presume that it would also work with STI. Now all I need is the travel
agent, and a 9-speed STI shifter. I don't suppose the 8-speed I have
sitting around would work.
Thanks for the information.
Ah, one note: it does work "backwards" from the way you'd be used to, in
that pulling on the cable puts you in a higher, not lower, gear.
> I've built a bike with this setup and it works very well. I used a 9sp
> barend shifter with a travel agent and an inline barrel adjuster. I was
> prepared to modify the Travel Agent ratio with a layer of masking tape
> and/or filing, but found it wasn't necessary. Here's a picture of the
> resulting bike:
> http://www.fischer-wade.homelinux.org/bici/
>
> You can find the Travel Agent here:
> http://www.excelsports.com/new.asp?page=8&description=Travel+Agent+%2Dea%2E+with+adjuster&vendorCode=PS&major=6&minor=8
--
David L. Johnson
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