Jordan said:
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big flange diameter and narrow flange spacing. Can't find any smaller fat direct drive motors.
That's unfortunately pretty much the definition of ebike DD hubmotors at present, fat or not, from all the ones I've seen.
Looking for something I could lace 1x at least. Its for a 2wd cargo bike so it will be supplementing a rear motor mainly for traction and for Regen. Don't want to go too big and stress the dropouts and id like to avoid radial lacing.
I know of no direct drive motors small enough to do anything other than radial lacing in a 20" wheel. Geared hubmotors, but not DD. The smallest diameter (by just a little bit vs typical ones) DD hubmotor I've personally had is the Ultramotor, which was used on some Stromer bikes, and A2B Metro, etc. Don't know that it's available anywhere except used off one of these bikes; they are nice motors though. However, still probably too big for anything other than radial lacing--it *might* be possible to do 1x...but it would likely be a PITA to do.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&start=1025#p1711799
There *are* some scooter hubmotors that might be small enough, but all the ones I've seen come with rims built onto them, not spoke flanges, so for those you'd have to machine something to replace the rim with. (which might require machining a new rotor and installing new magnets on it, depending on it's design and on how small a flange diameter you need).
THere are some with wider flanges, but they are also much heavier; QS205, MXUS 450x, etc. This image shows an MXUS 450x on the trike, and the not-yet-mounted Ultramotor off an A2B Metro (still in the complete Metro wheel) in a blue bike frame to do some testing using the SBC's controller/etc. It's hard to tell exactly how much different they are, but you can see that the spokes are longer on the Ultramotor wheel than the MXUS wheel, though both are 20" rims.
The ones I've seen are rear motors, but there's nothing stopping you from using them on the front--just don't install the freewheel cluster on them, since you don't need it (I did this with an ex-stromer ultramotor in a 26" wheel on a fatbike fork on SB Cruiser for a while, but the fork was very poorly made and began to fold up from braking forces, so the experiment was ended before I got any motor testing in--worked fine as a wheel, though). But they are all still the same large diameter, and still need radial lacing in the 20" wheel.
https://endless-sphere.com/forums/viewtopic.php?t=86600#p1466764
Would like to use a grin all axle motor but there's no adapters for a 135mm hub.
You can ask them if they can make one. The nice thing about that hub is that it is possible to make an axle adapter to work with quite a lot of setups.
Note that AFAICT the GAA DD hubmotor is also going to need radial lacing in a 20" wheel, but it's probably listed in the Grin spoke calculator so you could "build" it into one there to verify if it might work or not. .
FWIW, the radial lacing, if done with the right (thin!) spokes for the rim used, can still be plenty strong. Using radial-laced wheels I built onto the various motors I've tested (primarily the MXUS 450x's for the last long while until I started using the Ultramotors on the right side to replace a failed MXUS), I carry up to hundreds of pounds of cargo (groceries, dog food, dog, etc) in the back of the itself-very-heavy SB Cruiser, and have broken rims on potholes without breaking spokes, and even axles. I *have* had a couple of broken spokes on the left wheel (which is odd because most of the damage happens on the right due to being on the worst part of the edge of the road), but it's very rare.