At 11:13 PM -0500 9/21/05, Mark Stonich wrote:
>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
No, friction shifter originally intended for use with a Benelux Mark VII.
>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?
That was a typo, but I believe FMs can be converted the same way FWs are.
>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.
One of the keys to using the dual-cable setups is to realize that, contrary go folklore, they shift best (at least the left cable shifts best) whilst you are pedaling _forward_ gently. If you develop this habit, the spring becomes superfluous.
Also, a derailer-type friction shifter works MUCH better than anything from Sturmey-Archer for the left cable shifter.
Sheldon "Planetary" Brown
> See http://bikesmithdesign.com/
>rear is a Shimano tapped out to 13/32" x 26tpi. Thanks for the
>suggestion on your website about making a tap from an old axle. The
>threaded rod bit is from a Sturmey indicator chain.
>
>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
>
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>_______________________________________________
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