Uphill, no pedal, 20" 1000W 48V possible?

[Watt]

Hey! I'm new to this forum and last week I managed to get my 1000W 48V 26" rear hub motor from China to work with a 48V20ah battery and i love it!

I goes much faster than I expected also uphill if i help with the pedals.


My next project will be to build a trike with no pedals. I understand (by trying) that the motor I have now won't work as it doesn't have enough torque (right word..?) to drive me uphill unless I pedal. So my question is: If i buy exactly the same motor I have now, only in a 20" wheel, will that give me more than enough torque to go uphill without pedaling?

And what will happen to the top speed when its a flat road? The top speed with the bike I have now is maybe 50 km/h.

 

[wesnewell]

Mod your controller to put out 40A and it should take you up the hills fine.

 

[biohazardman]

A smaller wheel will definitely help on the hills and cut your top speed down. How much it will help depends on what your motor, controller and battery are capable of. Many systems are limited by a bms to help save the batteries, many have low amp controllers so they don't overtax the batteries and then there is the motor who knows what it can handle when connected to these limiting devices. Looks like you are adding some weight as well so another thing to factor in. I find the simulator here http://www.ebikes.ca/simulator/ to be helpful in estimating speed, wheel size and power needed to attain it.

 

[dogman dan]

The precise recomendation depends on the hill.

But one approach known to work is the 20" wheel. But nothing wrong with the go to 40 amps AND the 20 inch wheel. That really works. But only if your battery is up to the task.

20 inch wheel, 40 amps, then more volts till you have your speed back, now yer talking. Oh, just add money though.

 

[leffex]

So my question is: If i buy exactly the same motor I have now, only in a 20" wheel, will that give me more than enough torque to go uphill without pedaling?

And what will happen to the top speed when its a flat road? The top speed with the bike I have now is maybe 50 km/h.

Yes you will go uphill and you dont need to pedal anymore. I have the same wheel however 42km/h max in the 26" wheel, if i peddle uphill i get 35-38 and no pedal is 20-25 or step hills 15-20.

You will lose top speed with the 20" tire. New max is 20% lower so you guess your speed is 50, then you go almost 40 in 20". BUT you keep that speed uphill. i.e more torque in 20" tire than the 26".

tip... Have you got a 20" bike yet? what about a folding bike, 20" tires 14kg? 110quids? search on ebay for it -folding bike.

 

[Watt]

Thanks for great answers!

I think I'll try the 20" inch wheel without modding the controller first, and if it won't work I'll do that.
@ Leffex, I'm building a trike for a project at my university

 

[agniusm]

I have my scooter on 20" wheel and 48V 1kw motor running 36v with 30a controller. no problem going up steep hils. Max speed on flat 32kmh, going a steep hill, 20kmh.