Multispeed internal bicycle gear hubs

[jtr1962]

I was browsing a few bike sites recently looking for info on airless tires and came across this. Since we have quite a few cyclists here I thought I would share it. I was totally in awe since I've long thought that internal gear hubs were something limited to stodgy three speeds with upright handlebars. I was unaware that several seven speed models existed. And this one really had the gears going in my mind (no pun intended). 14 speeds and a total ratio span of 5.26:1 makes it virtually a CVT for bicycles! At nearly $1000 I won't be throwing away my derailleur any time soon but something like this would solve the gearing problem for wide speed range human powered vehicles. Thinking that I would never have any need for a gear less than about 40 inches (in fact my current sprocket spans 12 to 23, giving a low of 49 inches with my 42 tooth inner front chainring) I could use this 14 speed hub with the 15 tooth option and an 80 tooth front chainring on a highly aerodynamic human-powered vehicle. This would give me a low gear more than adequate for anything I'll encounter on pavement, and the highest gear (211 inches) would still allow 63 mph cruising at my usual cadence of about 100 RPM. Best of all, no front or rear derailleurs to complicate the drivetrain, and no worries about the chain coming off the sprockets either. Now if only the price was less I'd actually consider a 7-speed hub for my regular bike.

 

[twentysixtwo]

Yes, the Rohloff is just freaking amazing. I wouldn't call it a CVT though - the true advantage of a CVT is that it is "Stepless."

We have a Bike Friday Tandem, and it's a 24 speed bike - it has a 8 ring cogset with a 3 speed Shimano Nexus internal gear. Many folding bikes use this type of configuration since you can't get a front derailleur to work normally.

Internal gearing has come quite a ways, but a traditional derailleur is still better in many regards. It's much cheaper, has less frictional losses, closer gearing, and easier maintenance. Using it with a closely geared cogset eliminates the issue with close gearing. One of the guys here has his own HPV company, and he uses a combination of 2 internal hubs for a really ridiculous range....but that's another story....

 

[BentHeadTX]

Ahhhhh, the Rohloff hub!
Yep, it has been around for several years and is a very proven design. Sturmey-Archer (Sunrace), SRAM and Shimano have some interesting hubs out also. Sunrace and Shimano both have 8-speed internally geared hubs that are a less costly alternative (but probably not as durable)
Another interesting thing is the Schlumpf Mountain Drive or a internally geared two-speed crank. Tap the button on the crank and it will shift to the other gear so things can get interesting. It has a 1:1.65 and 1:1 ratios for smaller wheeled bikes or the 0.40:1 and 1:1 for the "mountain drive".
SRAM is rumored to have a 14 or 16 speed hub in the works, basically the 7 or 8-speed with another gear to boost the range.