3-speed fixed (bike) hub

Hey guys, just stumbled across this and thought you would be intrested. From www.cyclingnews.com

We are that much closer to a multi-geared uni hub :slight_smile:

Sturmey-Archer’s fixed-wheel three-speed hub will ship in early 2009
Photo ©: John Stevenson/BikeRadar.com

They have been making internally geared hubs for many years. Is this a special super cool one?

YES this is huge theres no free wheel so it would work in unicycle unlike the other hubs that that would just free wheel

I am almost absolutely certain that it would not be strong enough for any sort of unicycle use. Unicycling puts a huge amount of torque on the hub. Bicycles have a gear ratio that lessens the torque and the physics of bicycle riding doesn’t put as much torque on the hub.

I am excited about this development for my fixie bike. Seattle has some hills that can make fixie riding a challenge. Even just having a two speed shifting fixie would be nice. Just something to have a lower gear when you get to a steep hill. The three speed fixie hub is just extra.

It will be interesting to see what the specs are and what they specify as allowable chainring size sproket size ratios.

Did a bit of quick searching cause I couldn’t sleep and found that it has two underdrive gears and a 1:1 mode.

I was hoping that the design could be possibly built as a unicycle hub (with stronger parts) but we really arn’t looking for an underdrive hub.

You could set up a sort of jack shaft design with this hub sitting above your wheel to give you a 3-speed unicycle that you shift by hand instead of kicking the hub. The long chains would not be so elegant as having a true geared hub but it would definitely be doable.

I think I will file this away in the things to build when I have time and money to spare pile along with the GUWI I designed. I can picture it now, I could even do it without modifying the hub at all.

As far as bikes go I don’t have a fixie yet but I know one is in my future. Probably with a flip-flop though. maybe with some dingle gearing, don’t know what is all possible yet.

3 speed? Fixie? This makes no sense!

If it’s 3 speeds, I don’t think I’d call it a fixie, coasting or not.

sure it’s a fixie, just not a single speed.

Edit: Not as new of an idea as I thought.

I wonder if this hub can handle the stresses of skidding.

Somebody built an ASC into a giraffe and took it to unicon in Guilford. IIRC it had lot of play when you changed gear.

Sturmey ASC hubs, or 3- or 4-speeds modified to be fixed 2- or 3-speeds have quite a bit of slop/backlash in the gears - enough that a lot of fixed wheel bike enthusiasts say it takes away the feel of riding fixed. It would be a lot baggier than a Schlumpf uni hub.

@John: You could build a two-speed fixed wheel bike using a normal fixed hub and a Schlumpf Speed Drive/Mountain Drive bottom bracket. Probably quite heavy, but possibly no heavier than a Sturmey hub, and better weight distribution. (Or modify a normal Sturmey 3- or 4-speed hub (quite fiddly apparently) - or pay silly money for an original ASC!)


dang i complicity forgot about that

Don’t worry about it. Most people forget that, too. They also forget that internally geared hubs for bicycles are (1.) driven by a chain cog, not the axle which is fixed to the frame, and (2.) have a shifting cable that comes out of the axle which would quite handily wrap around your leg. There are three or four big issues working against internally geared bicycle hubs realistically being used on unicycles. Most people get pumped up even when they see the multi-geared freewheel versions which are completely unworkable for unicycles.

Fixie only implies that it doesn’t freewheel. The term is primarily associated with single-speeds since there aren’t any multi-speed fixed hubs currently on the market, and the one’s that exist are very rare.

Combine this with a symmetrical schlumpf bottom bracket (when they come out) and you have a 6-speed fixie!

Sombody’s got to penguin this thing up on a 29er with a big chainring!

It may not be a new idea, but just try and find one of those ASC hubs!

Why do you say that? It seems that for a given wheel size, at the same speed, there would be the exact same amount of torque for a unicycle as a bicycle. With a bike, the chainring amplifies the torque so that the rear cog sees the same amount as it would with a unicyclist powering it directly.

I have a free wheeling hub like that, I battered it out of a bike with a hammer and a brick :smiley:
I was going to take it apart and play around with it too see how it worked and design my own hub.

There is a lot of rapidly changing, high-magnitude torque applied in unicycling to maintain balance in the direction of travel.

In addition, the usual bike set-up with a bigger chainring at the front and a smaller sprocket at the rear, decreases the amount of torque that a rider can exert on the thing, as compared to a direct drive when the cranks are directly on the hub as we have on most unicycles. John Childs hit the hammer on the nail (or so) when he wrote “It will be interesting to see (what the specs are and) what they specify as allowable chainring size sproket size ratios.”

Our colloquial expression is, “hit the nail on the head.”

I thought it was “Nail, baby, Nail”…