RC e-bike STALL TORQUE

[phantom]

Hi all. I have recently discovered this forum and am left stunned by some of what I see! Needless to say the RC motor concept is increadibly intriguing.

I have a question for all those that have built a functional ebike or other vehicle with RC motors and the various gearing arrangements. Am I correct in assuming these things tend to be sort of all or nothing in performance? If some of these vehicles were given the fish scale test, i.e. using a fish scale to restrain the bike from moving under full throttle (breifly!), what sort of pull would we be registering at zero RPM? Are the typically available motor controllers able to perform well enough in these stall/low RPM conditions without further sophistication?

I have a weirdo application in mind and would love to use one of these arrangements, but its hard to make any engineering determinations with the typically spartan availability of actual and comprehensive full range motor performance specs. I would like to see some actual data, not theoretically calculated performance data....pretty please!

 

[gunthn]

We could have a contest.

Who's bike can break the fish scale first or tow the largest fish.

I am getting one at wmart in the morning.

 

[swbluto]

Torque is multiplied by the use of gears. Therefore, you could really get any torque you want (Upto to the point of breaking things) just by getting the correct gear ratio at 0 rpm. However, the higher the torque you gear it for, the lower the top speed, and there just becomes a point / range where the top speed becomes unacceptable to many.

 

[Doctorbass]

I would preffer a contest with (stall torque) x (max speed)

better performances indication!.. otherwise you could easy get a fool with a stall torque of 200lbs and a max speed of 15kmh...

see my very first setup:
5305 at 70V 50A

84pounds of trust and 64kmh max speed.. not bad! :wink:

[youtube]JQmddJT1e6c[/youtube]

Doc

 

[liveforphysics]

My bike does abrupt wheelies that will flip the bike right over on it's back if you don't let off. It will do that right from a stop with the flick of your wrist. That's with 220lbs of Luke hanging over the front handle bars. I've not quantified the stall torque, but it's adequate. If I had to make a wild guess, I would say maybe 5 times higher stall torque than I could personally generate with the pedals in a reasonable gear.

 

[fechter]

A sensorless motor is going to be unhappy at zero RPM. With a good senorless controller, the minimum RPM for proper operation is fairly low, but not zero. If the motor has hall sensors, then you can get full torque at stall.