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Special bike (old trial) converted but weak

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Triad:
Well, due to the weight of the bike (I think 60kg or so) and the weight of the rider (approx 80kg) and the specs of the motor (should be 5kw 48v) what should I get to make it able to ride uphill on steep climbs?

Bikemad:

--- Quote from: Triad on January 29, 2025, 10:22:08 PM ---What should I get to make it able to ride uphill on steep climbs?
--- End quote ---

With the original 16:42 primary belt reduction and 12:64 secondary chain reduction it should give a combined overall gear reduction ratio of 14:1 (or 15.27:1 with a 11T sprocket).
This is even lower geared than the Electro-Motion trials bike which only has an overall reduction of ~12.9:1 and that bike also uses the same 5kW motor.

Therefore, I still maintain that a 72V battery and BMS that can deliver 110 Amps continuously and 180 Amps peak should be all that you require to be able to ride uphill on steep climbs.

According to my calculations, if your motor is able to draw 110 Amps from the controller using a suitable battery, it should produce ~18Nm of torque @ 3,500rpm.
When this torque is multiplied by your 14:1 gear ratio (12T front sprocket) the resultant 252Nm of wheel torque should theoretically be sufficient to propel your 60kg bike and 80kg rider up a 35° incline (70% gradient) at a maximum speed of ~17.58mph (28.29km/h).  ;)

If the same torque were multiplied by a 15.27:1 gear ratio (11T front sprocket) the resultant 274.86Nm of wheel torque should theoretically be sufficient to propel your 60kg bike and 80kg rider up a 40° incline (84% gradient) at a maximum speed of ~16.1mph (25.91km/h).

Alan
 

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