Tuesday, December 30, 2008

4-Speed Again

This is the third time I've converted this bike to an internal gear (Sturmey Archer 4-speed). Maybe I've gotten it right this time.

I've had two problems using internal gear hubs with this bike in the past. The hub slips in the drop outs as if I hadn't tightened the axle nuts enough. This happens no matter how tight I make them.

The second problem is this bike has short horizontal drop outs. I haven't measured them, but they are just short enough to make it difficult to get the chain tension correct with certain cog/chain ring combinations. It seems that the ones I've tried are all difficult ones.

I've tried a few cures, but they didn't work. I mentioned this to Bikesmith and he sold me these beautifully made Sturmey Archer anti-rotation washers shown in the photo below. Previously, I'd only used stamped washers with a single "tooth." The new ones provide more surface area for the hub to bite into the drop outs. The new ones looked like they'd work, but they made the second problem worse by shortening the effective length of the drop outs. I tried this anyway and couldn't get the chain tight enough to stop the chain from jumping off the cog. So I put a rear derailleur back on the bike a month or so ago.




Compare my drop outs shown below with the array of drop outs shown on Sheldon's website (scroll down to the entry for drop outs). If my bike had long drop outs, setting chain tension would be easy.

A few days ago, I decided to try the anti-rotation washers again and add the chain tensioner mentioned in the last post. I installed it all today and gave it a ride. It seems to work. I've learned, however, that it'll take more time on the road to determine if it slips. Last year, I had it working until I installed clipless pedals in the spring. Then it started slipping again. I have hope for this setup though.



It's snowing and there are lots of ice ruts hidden under the snow. This prevented me from really putting the pressure on the pedals. It's time for skiing anyway.

3 comments:

Chris (veggie2u) said...

I'll give you a bucket of bonus points if you are still riding. Damn it's cold. Hope the thing-a-majigs work for you.

Rube Eclair said...

can I get a closeup shot of the handle bars on this bike I think I like the design are the upside down?
I'd like to see a couple body shots of it as well.
I like it.

rigtenzin said...

The bars are Origin8 Garys. Here's a post in my blog showing them:
http://3speedblog.blogspot.com/2008/11/winterized-bike.html

They are supposed to be shallow dirt drops and I have them installed as they intended. Although I've seen some three-speed bars turned upside down that look very similar.

I still love these bars and built another bike around them -- it's really nice too.

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