Smallest Ebike Hub Motor
 

Updated: I'm looking for some of the smallest (physical size, not wattage/voltage/weight) ebike hub motors. Extra points if you don't have to change gears... This is for an ebike build in which I will be placing motors on both front and back wheels, so any wattage motors are acceptable (above 250 that is...)

By their nature (no gears), direct drive (DD) hub motors are heavier (read the tutorial at ebikesca if you don't know why), The lightest motors that I'm aware of are Q100 from BMS battery (or other vendors); they're reported to be about four or so pounds and are available for front and rear conversions. Doubt you'll find a DD motor less than 8-10 pounds.

Smallest motor available ist he vivax assist:
vivax-assist.com/en/

Aotema makes the smallest available DD motors. Well under 10 pounds.

Cute motors are geared, and they also offer a 75 or 85 version, which are exceptionally small and light.

MXUS has some very small geared motors in a variety of models.

Tongsin also has some very small units, bit of a different design.

Smallest hub motor I know of is the Q85, at 1.8 kg (4.0 lbs) from BMSBattery.com for $131 shipped to USA. Their drawing in the link may be inaccurate. They advertise it as a front motor, but show one for 135mm dropouts.

https://bmsbattery.com/ebike-kit/369...ebike-kit.html

I have their Q100H, which checks in at 4.8 pounds on my bathroom scales. That's a small motor.

I've heard that the Xiongda may not be as small, but it's got two gear modes that allow it to climb steep hills and pull trailers. I had a quote ... it's more expensive than a Q100H.
https://xiongdamotor.en.alibaba.com/...59b8005fCYjDVi

Xiongda have recently re-designed the clutch and changed the composition of the gears, but they have a documented history of a very high failure rate. "Mechanically unreliable" and "Suffers from a serious design flaw" are just two users opinions, before the latest changes.

Very good warranty support, though.

Actually, the Q75 is the one he wants. the width of the Q85 is all wonky.
2.64 lbs.
I'm thinking of having them custom build me one in a version somewhere between 260 and 330rpm.

With that and my energy dense battery, the kit would add about 5lbs to the base bike.

https://bmsbattery.com/ebike-kit/593...ebike-kit.html