Motorized Shimano Hub Gear

[carbon.nanotube.capacitor]

Theoretically, if I were to run an electric motor through a Shimano 7 or 8 speed hub, how much torque could the hub handle? I can't find torque limits online and I'd love to run a motor through one to see how close to an electric scooter or motorcycle i can get with a small frame. Tee Hee!

 

[MitchJi]

Hi,

Gary posted this:
http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=5297&p=79741&hilit=rusty+spokes#p79741

I'm sure the Nexus hubs can handle the power. There's a guy with a bike shop down in San Diego (Rusty Spokes, in Pacific Beach...) who custom builds chopper-style motor bikes, using Etek and Mars motors. He uses these same Nexus 3-speed hubs with these beasts, and they have worked flawlessly, even pumping 15 hp through them. Instead of chain, hoever, his bikes are belt driven, using regular toothless v-belts. There's a little bit of "slippage" when starting out, which is like a clutch. Works great, he says, and these things can hit close to 60 in just 2nd gear. Anyway, he's never had a single problem with any of the Nexus hubs.

I emailed him, quoting Gary above. The following are my questions with his replies. He didn't actually answer the question but it sounds like he has used 7 speeds without problems and believes the 8 speeds are just as strong:

Do you know if the Nexus 8 speeds are strong enough to handle 2kw or 4kw peak?

more like 68.8 mph in 1st gear.

Thanks for taking the time to answer but I'm not sure I understand your reply. Does
"more like 68.8 mph in 1st gear" mean the 8 speed is strong enough?


i have only tried 3s and 7s , but im sure it is the same...

I just figured out the first reply didn't address my question at all but corrected the speed in Gary's post (I guess he considered "close to 60 mph in first gear" an insult :lol: ).

First thing next week I plan to start investigating the new Nuvinci LEV Kit. Before it was released they sent me an email claiming it shifts smoothly under power. Manual smooth shifting under power using custom shift maps would be nice. If the automatic works well it would be really sweet
http://www.fallbrooktech.com/09_Lev_Kit.asp

Manual or automatic control

Electronic Shift Actuator with integrated Position Encoder

Create custom shift maps and download to your vehicle through the NuVinci PC application software

I was tempted by the strength (rated to 5kw) and gear range but decided against it due to the weight (about 10 lbs). But shifting under power, custom shift maps and the possibility of automatic shifting have caught my attention.