3-speed mtb conversion

I recently rescued a Sturmey Archer AW 3-speed hub and all the gubbins that go with it (trigger shifter, indicator rod, cable & frame clips etc) from an old (but virtually unused) shopping bike, and I would like to build it into a 3-speed mtb for commuting and occasional offroad use. Just wondering if anyone else has done this?

The hub has an axle of approx. 145mm in length and the bike it came from had a rear triangle of 114mm OLN. I've been looking around for an old steel MTB frame with horizontal dropouts, with a view to cold-setting the rear triangle to 120mm or thereabouts to make it fit my hub axle.

Obviously it's quite hard to find old MTB frames with horizontal dropouts as that type of dropout was on the way out by the time MTBs became popular, so I've been wondering if it's possible to do the same with vertical dropouts - will the SA axle washer fit a vertical dropout?

(Yes I know I should buy a Shimano Alfine hub but that would be too easy - and too expensive)

can't advise I'm afraid but would be interested to see how you get on as I was thinking of doing something similar. Saw a few sturmey archer hubs go through ebay last weekend cheap... use a deore/xt thumbie to shift

ive got a spare hub on a shelf , thing weighs a ton , not sure if i would want to drag it around on the dirt

would have to be confident in its adjustment , wouldnt be nice having it freewheel both ways while wanting to put the power down

these ones I saw had a hub brake built into them so on balance the weight excess might not be too much?

Could you run a single chainring and use the hub gears as a sort of front mech? I'm sure my uncle said he used to use a 5 speed Sturmey hub.

Iwasgoodonce":320m2a86 said:

Could you run a single chainring and use the hub gears as a sort of front mech?

Click to expand...

That's what Sachs (now owned by SRAM) did with the 3x7 hub. It was a three speed hub gear with a freehub fitting for a 7 speed cassette. Theoretically you could have a 63 speed ATB! :shock: I think that the bars would be a bit crowded with all those shifters though.

SRAM have a more modern version available now called the dual drive. Now you can have 81 gears on your ATB.

http://www.sram-imotion.com/us/html/navigation_us.html

Click on products and then select dual drive II in the links at the top in red.

You'd need the longer, 6 1/4" axle and spacers to fit between your dropouts, and you will find the anti-rotation washers hard to get into the dropouts. But it's doable.
They aren't meant to be used offroad, Sturmey hubs aren't as well sealed as modern MTB hubs. Mind you, they're so cheap it's probably OK to go through one every year.
I have an AW complete and resplendent with long axle I might be tempted to sell if one of you was interested in such a project.
Use the fulcrum clip to route the cable along the top tube like on my Raleigh (click my for sale link below and scroll down to see what I mean), if it was routed along the downtube it will shift whenever you pedal too hard.

Alternative idea I've been tinking of, gearbox bike.

Bolt a chainring to the hubs flanges, I've seen it done and now SA have one as an option for trikes. Mount it in frame by some homebodged manner near B/B. Run chain to drive sprocket from chainset and run another chain from bolted on hub chainring to rear wheel sprocket.

Reason for this idea is SA hubs may not be strong enough for riguers of mtb life as long axle could bend etc. But a dedicated mtb rear wheel would be strong enough. Also puts heavey hub gear forward and central to help weight distribution.

One day I'll do this with an old nail of a frame and old 3spd hub I'm not bothered about drilling holes in.

there's a couple of these going through ebay at the moment

http://cgi.ebay.co.uk/NEW-STYLE-STURMEY ... 1|240:1318

I think you may run into trouble with the reaction arm trying to fit that into a frame with wider dropouts. Could run it without the brake though.
I love your gearbox idea. Hasn't there been a bike that does a similar thing with a Rolhoff?