170mm / 175mm Powerful (3kw+) Direct Drive Motor Options

[chuyskywalker]

From what I've been reading/searching, once you want to start getting into some big direct drive motors, people lean towards a few manufactures: QS, MXUS, NBPower, and a few others.

However, outside of NBPower, the major motor makers seem to only offer chonky direct drive motors in 150mm dropout sizes. There are occasionally one-off runs of something else, but finding a QS205 170/175mm dropout axle (at all, let alone laced into a 20x4) seems just about damn near impossible. Same for any mxus 3/5k. NBPower seems to do this, but there's a lot of contention around the quality of those motors when held up to the QS related variants.

(I'm shopping around because, sadly, my Grin Fat All Axle is turning out to be a lemon.)

Where are the fatbikes getting DD motors from these days, if they want to go big power, little (20") wheel?

 

[-Jöö]

Like you said finding a QS205 with a longer axle is difficult, wich is why you order it directly from QS motor If you need one, like i just did, i will lace it to a 100mm wide 20" rim (wich fits a 20X4" tire) with some Sapim spokes once i get it.

 

[thebes]

but there's a lot of contention around the quality of those motors when held up to the QS related variants.

Can anyone comment on the relationship between qs and nbpower? From what Ive gathered (or assumed rather...) they buy in bulk from qs and resell to other markets. Though in contrary to this belief, there were a couple threads a while back about nbpower qs205s having less copper fill than ones directly from qs. Im less inclined to believe that everything they sell is a clone though since I know someone personally who bought a qs273 from nbpower and later had it confirmed by qs that it was manufactured by them through the serial numbers (he was having issues with some of the windings shorting I believe). Not really sure where that leaves anything though Ive also shot over an email or two some time ago asking both nbp and qs about this but neither got back to me :/

 

[neptronix]

mxus 3kw is only 3kw rated in a 20" wheel, in a 26" wheel you may get a little over 2000w continuous.
QS motors seem good but they're bone crushingly heavy.
Don't know anything about nbpower.

Honestly i'd go with a mid drive / DD motor combo or DD + ~500w rated front geared hub motor combo before i picked some 24lbs QS motor.

 

[ganzey]

Can anyone comment on the relationship between qs and nbpower? From what Ive gathered (or assumed rather...) they buy in bulk from qs and resell to other markets. Though in contrary to this belief, there were a couple threads a while back about nbpower qs205s having less copper fill than ones directly from qs. Im less inclined to believe that everything they sell is a clone though since I know someone personally who bought a qs273 from nbpower and later had it confirmed by qs that it was manufactured by them through the serial numbers (he was having issues with some of the windings shorting I believe). Not really sure where that leaves anything though Ive also shot over an email or two some time ago asking both nbp and qs about this but neither got back to me :/

NB motors are made by QS, but QS will make them however NB wants them, so if they want to skimp out in an area, like copper, they will, and then they sell them at a lower price. There are so many variations floating around its impossible to say what exactly it will and wont have in common with the qs 205, you will have to ask. NB does sell a 20x4 kit with a 150/170/190 axle width options, you will have to ask for it though as i dont think they stock them. if you cant find a 20x4, get one on a 16" moto rim. IIRC the 20x4 they sell is radially laced. i laced one up in a cross pattern with a 16" moto rim and it was not fun, but has held up great to the abuse.

 

[neptronix]

Is leafbike 35mm out of the question? i think that's how you get a powerful motor without really insane weight, and a motor to bike interface strong enough to handle it.

 

[hillslayer@]

Is leafbike 35mm out of the question? i think that's how you get a powerful motor without really insane weight, and a motor to bike interface strong enough to handle it.

A leaf tuned up for max amps continuous on flat terrain with a bafang bbso2 running a 60 t chainring to help keep it cool on hills is the way.

 

[Tmoore1989]

Can a 170mm frame fit a 175mm motor?

 

[neptronix]

Can a 170mm frame fit a 175mm motor?

You might have problems aligning ae disc brake even if you use 2.5mm spacers on each side.
If we're talking about a 3kw rated motor tough, it should have great regen. if you are risk tolerant, your rear brake could be regen only.

 

[gromike]

Though not at full battery. Not that big of a deal if you know how to front brake.
I love regen braking.

 

[Tmoore1989]

I can definitely use regen and front brake thanks guys

 

[AdR]

I charge my 16s battery to 64V to make sure I always have regen