At 08:51 AM 9/19/2008, Pete Geurds wrote:
>From: "Mark Stonich" <mark@bikesmithdesign.com>
>>For perfect shifting or to get larger cogs I use a modified 7 speed
>>Shimano Cassette cog (pre-Hyperglide when possible) for the inner
>>cog, then a 1mm freewheel/fixed cup spacer then a dished small cog.
>>http://bikesmithdesign.com/SA/2Cogs2.jpg
>>http://bikesmithdesign.com/SA/2Cogs.jpg
>>http://bikesmithdesign.com/SA/CogMod.jpg shows how the cassette cog
>>splines are altered.
>>
>>When Jane was recovering from a knee injury I put a 22-34 pair on her
>>SA 5 speed hub. Her Huret Duopar shifted them as smooth as butter.
>>http://bikesmithdesign.com/SA/22-34.jpg <
>---------------------------------------------------------------------------------------------------------------------------
>Mark and list:
>Pretty interesting info in this thread.
>I thought I remembered reading about a maximum rear cog size on a
>S-A hub due to overloading the hub and stripping something.
>Maybe it was a newer/different brand of hub.
>That shot of the 22-34 is still impressive though.
Sturmey Archer recommended never using larger than a 22t and I'm sure this was to be in conjunction with a 46t chainwheel.
I ignore such prohibitions. My thinking is that this must have been based on a large, strong rider. If someone needs a 24 or even a 34t cog, it's because they aren't capable of pushing very hard on the pedals.
OTOH If a strong rider needs lower gears, on a cargo bike or such, then perhaps the hub could be overloaded.
BTW Jane's chainring is also 34t. With the S5, she had a low gear of 18 inches during her recovery. I believe Sheldon Brown's SA based 63 speed tandem was geared below 1:1
Mark Stonich;
BikeSmith Design & Fabrication
5349 Elliot Ave S. - Minneapolis. MN 55417
Ph. (612) 824-2372 http://bikesmithdesign.com
http://mnhpva.org