KonAaron Snake 

I'm trying to make the ideal winter bicycle....

Here's the key question...would a 3speed sturmey archer coaster brake hub work with a mountain bike? What I'd like to end up with is a mountain bike, straight top tube, with three speed internal hub and coaster rear.

I have the hub, off of an 80s Raleigh Colt, laced to a steel rim.

garage sale GT

I did some light trail riding with a Shimano Nexus 3sp c/b and it held up fine. You do want to find a frame with horizontal dropouts in order to avoid having to use a chain tensioner.

I don't know how well the Sturmeys are sealed. It is possible grit would get in there somehow especially if it wouldn't get stuck in grease before doing any harm. It would circulate through the oil on an old Sturmey.

They offered a heavy duty, offroad AW during the early bmx craze in the 80s. I think they would really prefer you didn't put too much hard offroading on the standard ones. Shimano says so too in their tech pages on their site.

KonAaron Snake 

Nah...I'd be using it as a winter commuter, not winter trail riding.

garage sale GT

Nothing seems to stir up the grit like a slushy winter ride. I got back last Tuesday and my shoes and the bottoms of my pant legs were just coated in grit. Maybe because water can't freely flow off the road surface but only serves to carry the stuff onto you and your bike.

I think the bearing between the hub and sprocket carrier is already sealed with a felt washer. You could cut sealing rings out of felt for the cones which would block grit. Or, I guess you could just try it. No one seems to talk about how their s/a got trashed with grit.

anyway, find an old mountain frame which fits you and has horizontal dropouts. I think the mild steel frames hold up fine in the winter whereas some grades of aluminum are very susceptible to salt corrosion.

EjustE

I think that the setup will not be wide enough to fit the 135mm spacing of the mountain bike so you might have to be creative... and fairly creative because I think the spacing for those hubs is 110ish mm... Another option is to use a "silent clutch" hub (those have been temperature rated to below zero F) Not sure whether the internal gears will have problem with the cold, but I guess if you are going to be riding in Philly and not in a place like Minneapolis, it might not be an issue, but the 25mm difference will be an issue

Harris offers a new version that can fit up to 135mm frames, but the price is pretty steep: https://www.sheldonbrown.com/harris/s...cher-hubs.html

garage sale GT

Steel frames can be respaced.

noglider 

Yeah, if you can get the rear spacing problem solved, it would make an excellent winter bike. The Sturmey Archer hub is good at keeping gunk out of the mechanism. Add oil every month for ideal performance. Motor oil, bike oil, or ATF.

EjustE

Yes... from 126mm to 130mm often to accommodate modern hubs and cassettes on 80s bike. But that is a 4mm change, not a close to 20-25mm (that is about an inch) and closing instead of opening the frame, which would be required for something like this... I think that spacers might be the solution here

gomango

Respace the rear and run it. Use ATF, I do on my three speed Racer and it runs super smooth. You'll be fine. Really, what's the worst that can happen? Wreck it? It would get me thru this storm we are having, so I'd let her rip. I just got back from the grocery store on my Miyata SS, and from my experience, I'd worry more about tires than that hub. As for the coaster brake idea, I have not tried that. I just use cantilevers with Kool-Stops year round. I don't go fast enough to create stopping issues, especially in eight inches of new snow.


St. Paul, Minnesota is home of the "historic" 2009 Christmas storm.

Oh, a Surly spacer kit works great as well.

KonAaron Snake 

It seems like the tricky part would be geting a mtb frame with vertical drop outs. I was planning on using a tensioner, but apparently that would ruin the coaster brake.

noglider 

Another concern is rider position. Mountain bikes have the rider leaning forward pretty well, which might make it hard to apply adequate weight to the coaster brake. If so, be sure to have at least a front rim brake, and be sure to use it.

EjustE

not that historic in my last (for good reason) winter up there 1992, there were 3+ feet snowstorms on Halloween, around Thanksgiving and around Xmas. The Halloween one shut down everything. Great XC skiing to work from NE Mpls to DT Mpls down main arteries, though

nlerner

You can get a 6 1/4" replacement axle (rather than the standard 5 3/4"), which with a couple of spacers on both sides fits fine on a 120mm rear triangle. If the MTB is spaced at 130mm, I'd just crank down those axle nuts for a poor man's cold set.

The one caveat is I don't know if the axles in the coaster brake hubs are the same as in the AW. Anyone?

Neal

gomango

The local media and the national weather service would have you believe it is the end of the world as we know it. Inconvenient maybe, end-times, I think not. We are going cross country skiing at the Highland Park Golf Course in twenty minutes. I hope we survive. Happy Holidays to a fellow "former" Minnesotan! Now, back to regular programming.

garage sale GT

It all depends on how you kick. If you had a lowracer recumbent with a coaster brake, you would just have to kick at 12 o'clock.
.
I used to use a cruiser from a big box store as my winter commuter. I fitted it with some nearly straight hybrid style bars. Same with the 3 speed nexus. They braked fine even though much of my weight was over the bars.

garage sale GT

Two other caveats: One, Is it an AWC or an S3C? Consumer Reports found the S3C could go out of adjustment in a way which not only left you without power but also left the sprocket uncoupled from the brakes.

Two, How is the C/B itself lubricated? I am not too sure about old sturmeys. I think I got plenty of extra workout riding around in the winter with a c/b because the ones with steel pads are designed to be grease lubricated. The pads run pretty close to the hub and what with the grease being cold, you will have plenty of drag. This isn't the same as hub bearings because they're not rolling. You have two big, flat brake shoes inside a turning hub, maybe half a millimeter from it, constantly shearing a layer of cold, thick grease.

I relubed my Nexus with oil and it was too thin. The c/b made a horrible scraping noise and I found it was deeply scored when I took it apart to regrease. So you can't depend on oil if it's designed for grease.

garage sale GT

There are lots of old mtbs on craigslist with horizontal dropouts. I have an old Roadmaster frame and fork.

gna

+1. It's Minnesota, for crying out loud.

EjustE, the '91 Halloween Snowstorm is the standard I judge other storms by, primarily because no one was ready for it.