John in CR
100 TW
Toolman2,
You're talking about using the same motor for two totally different uses, so sure a difference in gearing can be worthwhile. The tranny better be light though, because a bigger motor can do both your mountain climb and road run as a single speed. What top speed did you need on the road? I ask because I'm building a trail bike to take big ole me up the mountain trails, and gearing it down to a top speed of 60-70kph will make the 10kg motor more than capable as a single speed, and that's with a 170-180kg all up load on 74V nominal. If it seems lacking, I'll just up the voltage and number of teeth on the driven sprocket. Since it already handles 20% grades with ease on the road, I'm pretty sure the planned 40% reduction will be enough. Then I can go up in voltage for an 80kph or higher top speed and still excel on the trails, or with a controller swap go to 30s instead of 20s, and split it with an additional 25% gear reduction and 25% increase in no load for an on and off road single speed beast.
The lack of an appropriate motor or gearing them too high or sending the stator too far into saturation account for most problems, not a lack of a gearbox.
John
BTW- The extra 3 teeth definitely won't make it more efficient, and often won't even give it more top speed. Instead simply use the 3 teeth lower gearing, use a higher voltage, and forget the tranny.
You're talking about using the same motor for two totally different uses, so sure a difference in gearing can be worthwhile. The tranny better be light though, because a bigger motor can do both your mountain climb and road run as a single speed. What top speed did you need on the road? I ask because I'm building a trail bike to take big ole me up the mountain trails, and gearing it down to a top speed of 60-70kph will make the 10kg motor more than capable as a single speed, and that's with a 170-180kg all up load on 74V nominal. If it seems lacking, I'll just up the voltage and number of teeth on the driven sprocket. Since it already handles 20% grades with ease on the road, I'm pretty sure the planned 40% reduction will be enough. Then I can go up in voltage for an 80kph or higher top speed and still excel on the trails, or with a controller swap go to 30s instead of 20s, and split it with an additional 25% gear reduction and 25% increase in no load for an on and off road single speed beast.
The lack of an appropriate motor or gearing them too high or sending the stator too far into saturation account for most problems, not a lack of a gearbox.
John
BTW- The extra 3 teeth definitely won't make it more efficient, and often won't even give it more top speed. Instead simply use the 3 teeth lower gearing, use a higher voltage, and forget the tranny.