At 9/21/2005 08:53 PM -0400, Sheldon Brown wrote:
>At 7:30 PM -0400 9/21/05, Phil Sieg wrote:
>>SA seems to be a popular topic of late. This may be a dumb
>>question, but is it possible to use another shifter with an AW or
>>FW rear hub? Specifically, I have a Cyclo 3sp DT shifter (that
>>mates with the appropriate RD). I would like to use it with a SA rear hub.
>>The frame for which it is intended has a DT boss for the Cyclo and
>>I think aesthetically it has it all over the SA trigger jobs. But
>>is this just asking for trouble or can it be rigged? TIA.
>
>I ran my Sturmey-Archer ASC hub with a Cyclo down-tube shifter for
>quite a few years, no problems with it.
Sheldon,
Is this shifter indexed or did you shift by feel? Or? If it's
indexed, ASCs used a different amount of cable travel between gears
than an AW or FW
>For an FW you would need to crank down the friction pretty hard
>onacountta the extra spring. I don't think I'd recommend that,
>though I haven't actually tried it.
>
>If you really want to use an FM this way, best to locate an S-5
>bellcrank and convert it to 5-speed/dual cable operation.
I wasn't aware FMs could be converted, or was this a typo? I've converted a few FWs to S5s and the bellcrank is the easy part compared to finding an S5 primary sun pinion. Unless the FW is a very early one, the sun pinions have dogs that are tapered on one side for better shifting. Unfortunately, they will transmit force in only one direction.
BTW you can improve shifting between ranges on the bellcrank type 5
speeds, by putting a tension spring between the lever and the
threaded rod bit. Without it, if the square ended dogs on the
primary sun pinion butt up against the square sided dogs on the axle,
the cable stops moving and you can end up between ranges. With the
spring, the cable keeps moving. Then when the dogs are no longer
aligned, the spring finishes the shift.
See http://bikesmithdesign.com/
Once you add the spring, the S5 is preferable to the dual indicator chain models, which were designed to eliminate the same shifting problem. This is because the sun pinion springs are only under compression when in ultra wide ratio mode, which in my experience is only about 5% of the time.
BTW2 the home made tap will cut a bit undersized if you use the worn ends of the axle. Better to make it from the fresh threads near the center. I used a cutoff wheel in a Dremel, took all of about 5 minutes.
>Sheldon "Epicyclic" Brown
Mark Stonich;
Minneapolis Minnesota
http://mnhpva.org
http://bikesmithdesign.com