Singlespeed & Fixed Gear - Multi-speed fixed gear?

OK so since SA looks like they'll be releasing the second coming of the ASC sometime after never, it got me wondering about other multi-speed fixed gear solutions. Teaming up with a machine shop to do limited batches of any of the 3/2 or 5/4 conversions online is one way to go. But the other day I was looking at internal gear hubs and noticed that the SRAM IMotion 9sp hub takes a standard freewheel that spins onto threads outside the hub instead of having the freewheel mechanism inside the hub like Shimano. How hard would it be to machine the threading down and add a new thread for a lockring? Would the hub work the same backpedalling as it does in forward motion? It might be interesting for anyone who has one of them (maybe one of those spiffy new Swobo bikes?) to thread a track cog on for some experimenting... Could be a sweet, simple solution... and you'd be the first on your block with a 9sp fixie...

Or...

The IMotion is disk compatible, as is the Shimano Alfine. Use rim brakes and add one of those bolt-on cogs to the disk side and you'd (theoretically) get a fix/8(9)sp flip flop hub. Or would the counter-rotation do something funky to the hub gear internals?

This post was much better than i was expecting it to be.

But you should have mentioned the nuvinci hub as well.

I don't think the disc cog idea would work. The disc doesn't shift gears as a brake disc.

This post was much better than i was expecting it to be.

But you should have mentioned the nuvinci hub as well.

The NuVinci takes a freewheel or a disk/fixed cog? Sweet, so that might work as well...

Don't forget about the Schlumpf two-speed planetary bottom bracket. They've adapted it to work on unicycles, so a 6 speed fixed Schlumpf/ACS bike should be doable with existing (if expensive) parts.

I don't think the disc cog idea would work. The disc doesn't shift gears as a brake disc.

No it wouldn't work for as a geared fixie, but I'm wondering if it would work as a flip-flop hub--you got your 8, 9, or infinite speed on one side, flip the wheel over and you're riding a 1sp fixed gear. Wouldn't work if you got the roller brake on the shimano hub, but if you're using rim brakes it might.

Just brainstorming, throwing this stuff out there. I don't have a disk compatible IG hub or an IMotion to actually try these out with; wondering if someone around here does and is curious enough to try...

Don't forget about the Schlumpf two-speed planetary bottom bracket. They've adapted it to work on unicycles, so a 6 speed fixed Schlumpf/ACS bike should be doable with existing (if expensive) parts.

I thought Schlumpf was specifically no-fixie application?

The NuVinci takes a freewheel or a disk/fixed cog? Sweet, so that might work as well...

just a freewheel, but he was talking about machining things, so I figured I would throw it out there. But screwing it up would be very expensive.

As far as I know, it is the second most expensive hub, not counting those from tune/ax lightness/ other stupid parts companies.

I thought Schlumpf was specifically no-fixie application?

They say not to use it, but like I said, its been adapted into a unicycle hub, so fixed gear operation can't be that bad for it. It might not be up for heavy brakeless use, but it'd work.

I knew a guy who had a multispeed fixed-gear, but he couldn't backpedal it on the reduction gear. Actually, he may have not been able to backpedal on it at all, which kind of defeats the purpose.

They say not to use it, but like I said, its been adapted into a unicycle hub, so fixed gear operation can't be that bad for it. It might not be up for heavy brakeless use, but it'd work.


The method of changing gears would scare the heck out of me at anything other than the lowest of cadences.

For those who aren't aware you'd have to press the crankarm toward the bottom bracket with your ankle/calf (normally you'd use your heel but on fixed you'd cop a pedal-whackin' trying that). You mistime flicking it with your ankle or calf on a fixed gear and I reckon it could mean lots of pain.

The method of changing gears would scare the heck out of me at anything other than the lowest of cadences.

From reading about the uni application of the schlumpf, there's a button that sticks out where you'd normally expect the crank arm bolt to be, and all you have to do is angle your heel in a bit and tap it on the way past. Once you get the hang of it, its pretty easy. Or so they say.

for some unknown reason the Nuvinci has a built in freewheel so no fixed gear joy there.....