drewdiller
100 W
- Joined
- Nov 5, 2009
- Messages
- 172
Hey guys, ballpark question here:
If I were to hook up a bicycle crankset to a generator, and connect the generator directly to a hub motor such that human pedaling would (almost) directly power the hub, what kind of efficiency loss am I looking at? I realize that I would be paying an efficiency penalty twice (once at the generator, another at the motor), I'm just unclear on how efficient a typical hub motor actually is.
Basically the idea is to drive the bike with human power only, but with no chain, and no perpendicular drive shafts.
BUT WHY?
Here is the pie-in-the-sky potential application for such a silly idea:
I ride a "fat" bike (a la Surly Pugsley) in the winter, with tires that are almost 4" wide, so you can float on snow better and steering is somewhat sane.
There are two common problems with snow bikes as I see it:
1) The bottom bracket shells are 100mm wide, and the increased Q factor hurts some riders' knees.
2) Sometimes I wish for even more flotation.
I had a silly idea that removing the chainstays (yes, the rest of the rear half of the frame would need to be built to compensate) would allow me to either put the cranks closer to the sides of the rear tire, or increase the overall width of the tire... but the chain would run into the tire. So, use some alternative to a chain drive.
I know it sounds crazy, I'm just looking for numbers. There is also the idea of long chainstays and a transaxle, which has been realized already in the form of a Hanebrink bicycle.
If I were to hook up a bicycle crankset to a generator, and connect the generator directly to a hub motor such that human pedaling would (almost) directly power the hub, what kind of efficiency loss am I looking at? I realize that I would be paying an efficiency penalty twice (once at the generator, another at the motor), I'm just unclear on how efficient a typical hub motor actually is.
Basically the idea is to drive the bike with human power only, but with no chain, and no perpendicular drive shafts.
BUT WHY?
Here is the pie-in-the-sky potential application for such a silly idea:
I ride a "fat" bike (a la Surly Pugsley) in the winter, with tires that are almost 4" wide, so you can float on snow better and steering is somewhat sane.
There are two common problems with snow bikes as I see it:
1) The bottom bracket shells are 100mm wide, and the increased Q factor hurts some riders' knees.
2) Sometimes I wish for even more flotation.
I had a silly idea that removing the chainstays (yes, the rest of the rear half of the frame would need to be built to compensate) would allow me to either put the cranks closer to the sides of the rear tire, or increase the overall width of the tire... but the chain would run into the tire. So, use some alternative to a chain drive.
I know it sounds crazy, I'm just looking for numbers. There is also the idea of long chainstays and a transaxle, which has been realized already in the form of a Hanebrink bicycle.