High power ebike frame

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John1deere   100 mW

100 mW
Posts: 42
Joined: Jul 09 2018 2:54pm

Re: High power ebike frame

Post by John1deere » Aug 27 2018 3:09pm

brumbrum wrote:
Aug 27 2018 1:57pm
QS273 is the completely wrong motor for your purposes. You do not need 20kw for off-roading. 20kw peak power is just over the top and a waste of battery fuel. The weight of a 273 in a motorbike rim and a mx tyre is going to be like having the Titanics anchor attached to the rear end of a trail bike. what kind of trails are there where you need 70+mph? 50mph is plenty and can be done with a cromotor or qs205. I have a cromotor laced into a 17" moto rim with a 3" mx tyre and it weighs 20kg, which is more than enough to have at the rear end.
You also dont need 200 hp sport bikes on the road but their damn fun to ride. My background is motocross and i would regularly run 60-80 mph in trails.
I just want to ride something that will feel similarish to a motocross. Something that will give me adrenaline and have great acceleration even at higher speed. But all i tryed so far is my 3kw conversion and its far from what im looking for and i have no idea where that point is so i would rather overshoot than undershoot and have to do it again.
I can always turn down the power if its too strong but the other way doesnt work unless i buy more parts. Qs205 is probly what im going to get tho since 273 seems ridiculously heavy. Or cromotor ill have to do some research on whats available in that size.

So yeah my 3kw is great for riding around but i want a 2nd ebike for the fun factor only. If its 10 kw then great ill save some battery life. If its 20 kw then ill have all i need to do that.

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brumbrum   100 kW

100 kW
Posts: 1280
Joined: Oct 30 2010 3:29pm
Location: Wales U.K

Re: High power ebike frame

Post by brumbrum » Aug 28 2018 7:00am

Cromotor or qs205 will take up to 12kw as long as you put some statorade inside the hub to allow a pathway for heat to get out. If you don't know what it is, it is just about 8ml of ferrofluid oil that sticks to the magnets in the motor and closes the tiny gap between electomagnets on the stator and the permanent magnets on the outer spinning part of the hub.
Remember that most if not all largish motors tend to use only about 60amps when up to speed. Larger power is just for initial acceleration and peak amps only last a few seconds at most and then slowly lower to the continuous amps needed by the motor to cruise.
The qs205 can be bought straight from QSmotors and you can ask for differing turn counts which effect top speed. The lower the turn count the faster the motor, but generally this will make it less efficient off-roading and will create heat. 9kv (probably 4 turn) will get you up to 50mph. 11kv (probably 3 turn) will take you faster. Kv is basically how many rpm the motor is designed to do per volt. Also remember that the smaller the diameter of the motor wheel the faster acceleration will be and the motor will be more efficient as it will find it esier to reach its designed rpm. Though a smaller diameter wheel will effect top speed a bit.
My NYX and cromotor build
viewtopic.php?f=6&t=74615
My LMX 161 dirt bike build
viewtopic.php?f=6&t=94074

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