E-bike brushless motor problem

[Racoon]

Hi guys! So today I finished my fatbike and just put a 3S battery for a test drive, first thing I noticed was that the motor won’t start from zero (starts to make some noise) but only if I give it a little push then it runs fine. If I start to ride the bike with pedals and start to add throttle it runs fine if I add it slowly. Thing is I have the exact same setup on two longboard and they all start from zero without a single problem the only difference is that I didn't try 6S on my bicycle. Please help

Setup:

5065 sensorless 320kV
3S 5000mah 25C (two in series)
Mystery Fire Dragon 80A ESC
34T Sprocket with 10T pinion on a 415 chain.

 

[amberwolf]

Longboards have MUCH smaller diameter wheels, so the effective motor-to-ground gear ratio is much lower for the same reduction ratio between motor and wheel.

So I'd guess that 3s on the LBs didn't have the same issue.

What you need to do is determine the difference in size between the LB wheels and the FB wheels, and then change the drive ratio between motor and FB wheel so it comes out the same effective motor-to-ground ratio as the LB has.

This means either making the motor sprocket smaller, or the wheel sprocket larger, by the ratio between the LB and FB wheel sizes.

The difference may be so great that you can't do it in one stage, and may have to add a jackshaft with a second reduction.

 

[Racoon]

I get it, but I didnt't think of it since the motor can be rotate by hand with ease even with a rider on the bike. What I did notice is that the wheel spins stupid fast on 3S on full throttle.