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Tech Help / transmissions
« on: March 31, 2009, 08:11:34 AM »
Hello, all!
I'm proud to say that I just completed my first electric motorcycle conversion two weeks ago! By this point, I've had enough time to give it some good runs, and boy is it lame!
Predictably lame, I mean. It's a six to one gear ratio with a motor who's peak load rpm is 3300. The acceleration is fantastic, but a top speed of 40mph?
Don't get me wrong. The bike's a blast to drive--especially living in downtown baltimore. But all this time designing and building this conversion--and now riding it--there's one question that's been burning in the back of my mind:
Why not a transmission? I know this isn't a revolutionary idea--many have already used it in their conversions--but I'm a little surprised to see that it isn't more popular. I mean, I can understand the beginner wanting to keep it simple, which a direct drive system certainly is, but I'm a bit flabbergasted over how commercial electric motorcycle companies that are pioneering the industry refuse to design anything other than direct drive systems.
Am I missing something? Sure, you can get 70-80mph with these Sepex/AC Motors with their high peak RPM, but it seems that running them that hard is just a waste of juice. It seems to me that except for maybe the smallest of bikes, the trade-off of one battery for a tranny makes for an obvious choice. Think about cruising at 70 while the motor is still in its efficiency "sweet spot." And I'd think that with the torque curve of electric motors, you could get away with a 2 or three speed with still considerable performance enhancement while not adding much in weight and loss of space. Let me know what you think.
If there's one reason it may not be so mainstream, it could be availability of such transmissions. Google has failed me in finding anything relevant to a simple, self-contained 2/3 speed transmission. Can anyone give me some direction or recommendations in this department?
Thanks
I'm proud to say that I just completed my first electric motorcycle conversion two weeks ago! By this point, I've had enough time to give it some good runs, and boy is it lame!
Predictably lame, I mean. It's a six to one gear ratio with a motor who's peak load rpm is 3300. The acceleration is fantastic, but a top speed of 40mph?
Don't get me wrong. The bike's a blast to drive--especially living in downtown baltimore. But all this time designing and building this conversion--and now riding it--there's one question that's been burning in the back of my mind:
Why not a transmission? I know this isn't a revolutionary idea--many have already used it in their conversions--but I'm a little surprised to see that it isn't more popular. I mean, I can understand the beginner wanting to keep it simple, which a direct drive system certainly is, but I'm a bit flabbergasted over how commercial electric motorcycle companies that are pioneering the industry refuse to design anything other than direct drive systems.
Am I missing something? Sure, you can get 70-80mph with these Sepex/AC Motors with their high peak RPM, but it seems that running them that hard is just a waste of juice. It seems to me that except for maybe the smallest of bikes, the trade-off of one battery for a tranny makes for an obvious choice. Think about cruising at 70 while the motor is still in its efficiency "sweet spot." And I'd think that with the torque curve of electric motors, you could get away with a 2 or three speed with still considerable performance enhancement while not adding much in weight and loss of space. Let me know what you think.
If there's one reason it may not be so mainstream, it could be availability of such transmissions. Google has failed me in finding anything relevant to a simple, self-contained 2/3 speed transmission. Can anyone give me some direction or recommendations in this department?
Thanks