I recently stumbled upon a good deal for a Sturmey-Archer 3-speed hub, pre-installed in a 20" wheel, which I thought might make a good upgrade to a single-speed folder (original thread below):
Well, the wheel finally came in today, and I have some mechanical questions I was hoping someone could help me with. The hub is the SRF3 175mm-wide model (127mm OLD), and it's going into a Schwinn folder with 110mm between the rear forks (knew this when ordering).
First, there appear to be three spacers total on the axle. On the right (sprocket) side, a dark 3.2mm spacer. On the left side, one dark 3.2mm spacer, and one silver 4.8mm spacer. If I were to take them all out, that would give me an OLD of about 114-115mm. Now, the Sturmey Archer website lists two other variants, a 148mm-wide version with an OLD of 108mm, and a 163mm-wide version with an OLD of 117mm:
Apparently, the hub itself is completely the same between the various models. So a few mm get shaved off somewhere, since the spacers aren't enough to count for the extra distance. In an older post on bikeforums:
...there's a mention about Sheldon Brown narrowing down a hub by using some Sturmey-Archer "skinny nuts". By this, I believe it means the inner cone locknuts, and that there is a thinner type than what is on my hub. If this is correct, Anyone have the model numbers of these thinner nuts, as sites selling these don't seem to list the thickness of the nuts?
Also, since there is an uneven thickness of spacers on each side being taken out... I asked someone at the local bike shop about the feasibility, and he was concerned that the wheel would be slightly shifted to one side if I did so, and therefore I should only take out an equal amount from the two sides of the axle. How important is it that the wheel be perfectly centered? If I just take out the two black spacers, I will be at about 120mm OLD.
In addition, the axle ends will end up sticking out too far from the frame, and interfere with folding. I could cut it with an Angle Grinder or Dremel (guy at LBS was willing to try). but I wanted to see if anyone had any suggestions about how practical it would be to do so. A problem is that the indicator chain plugs in to one end of the axle, so that not only would I have to be extra careful not to damage something there or get any metal shavings in the works, I might need a new shorter indicator chain. The shortened axle length probably wouldn't line up exactly with one of the official SA sizes, which might mean problems with lining up the indicator chain's adjustment mark too.
Also, I would feel kind of bad destroying a 175mm axle, as if the below thread is correct, they aren't widely available SA hubs, and some people need them:
As an alternative, I e-mailed Sturmey-Archer, who suggested I get the correct 148mm axle and put it in (Part HSA621). Unfortunately, not a whole lot of places carry it in the U.S. Is the replacement process sufficiently simple that my LBS wouldn't mind if I asked them to do it? Is there someone with a short axle would needs the long one and would want to swap?