Fallbrook Technology will manufacture (and has already licensed to Ellsworth Cycles) this new Constant Velocity Transmission hub, named NuVinci. It has continuous ratios from 1:1 to 3.5:1, but is made as a normal freewheeling bike hub. Maybe they could be persuaded to make a fixie version?
http://www.fallbrooktech.com/NuVinci.asp
3.5:1!!! Holy cow…That would make a 29er into a 90" wheel…Thats nuts in my opinion…But hey what do i kno about such things as this.
i saw that in Moution Bike Action and was thinking the same thing
does that design gradually increase the ratio as you pedal faster? Not sure that I am exactly a fan of that.
if anyone’s interested I have a Nuvinci hub sitting on my desk currently. It will never make it as a unicycle hub in anything like its current guise. The ratchet is easily removed but the hub won’t sustain large reverse torques, so will slip when you try and slow down. Also this thing is heavy like you wouldn’t believe
the last part looks strange to me because i have tried a bike with the nuvinci hub and i could stand on the pedals and it dit not slip
although when i put force on the pedals you can not shift
and indeed this hub is to heavy
kington99 specified reverse torque. The CV hub is probably designed so that the frictional force is increased with forward torque (like a rotating lock down) and decreased with reverse torque. Hence, you can stand on the pedals and it won’t slip and you can reverse the direction and get it to slip by hand.
Sturmey Archer and some other free-wheeling geared hubs have a directional design, also. Their gear teeth are more like ratchets and will easily lock in the forward direction but slip in the reverse direction.
indeedy, as far as i understand the hub works by the properties of a non-newtonian fluid, it effectively goes solid when trapped between the ball and the cone. Presumable when running in reverse the fluid isn’t subjected to suitable pressures to cause this effect, allowing it to slip. Haven’t tried this myself but it is the accepted wisdom of other car racers who use them, it;s significant as it throws out the possibility of regen braking
oke i did not read that part good i think englich is alsow not my first
i can see how it would slip because of the no torgue at the point you are starting to push backwards.
i know how the other geared hubs work (working on the saterday;s at my lbs)
I am keen on the potential of the duvinci hub for unicycle use,however it would require a bit of re-engineering in order to be suitable.The standard hub is listed as having a gear range of 0.5 to 1 ratio through to 1.75 to 1 ratio,this range of gearing would be very suitable for a unicycle.An example with a 26" wheel would be an effective range of 13" through to 45.5" I think that would cover almost all gearing requirements.
I emailed about 6 months ago and they said they have no intention at this stage to make a unicycle hub.
The reply
John,
We appreciate your enthusiasm for the NuVinci CVP. At this time, we don’t have plans to adapt the hub for use in a unicycle. Maybe someday…
Regards,
R. Scott Harris
Director - Customer Services
ATC
9901 West Reno
Oklahoma City, OK 73127
Ph: 405-577-9925
Fax: 405-577-9922
Cell: 405-229-2507
sharris@autocraft.com
www.atcnuvinci.com
That actually doesnt look so complicated (in theory anyway) If that was to be made into a unicycle hub, it would be possible to get so many different gears out of it. They should make a unicycle compatible one!
The list of things that other people should do that don’t look so complicated is practically endless.
I noticed that… quite a few of my ideas have ended up on that list. I’ll try again one day.
harper stop bitching and get it done lol.
I know! CVTs are the essence of simplicity. (Especially if you are under 16).
corbin
Sorry. My bad. What’s with the punctuation at the end of your sentence? You already ended it with “lol.” Isn’t the period redundant?
There’s virtually no reason to gear a unicycle hub down below 1:1, and given the number of people now riding 54" effective wheels, 45.5" is pretty wimpy.
I think the ideal range for a unicycle gearing system would be from 1:1 to about 3:1. If we ever get 3:1 gearing, I expect high-end unicycling to move towards 700c wheels and 170mm cranks.