Hub motor Rim Recommendations (26", 36h, 10g spokes)

[maarten_almighty]

Hi all,

I recently purchased a new hub motor for my ebike and am looking for a rim to use for the wheel build. I'm having trouble finding a rim for the correct gauge (10g) spokes in 26". The motor has 36 holes, drilled for 10G spokes. The motor is a Suringmax (link: https://nl.aliexpress.com/item/4000212162738.html?spm=a2g0s.9042311.0.0.27424c4dPNfoDT).

I considered using a 'normal' mtb rim(for example sunringle mtx33 or mtx39 (if i can find the mtx39 model, they appear hard to come by)) (which only accepts 14g or 13g spokes), choosing a non-eyeletted version and drilling the holes to the size needed for 10g... but i think this is risky business (i'll create weak spots/stress concentrations by drilling the holes... and i don't want the rim to fail at 70kph).
Would you agree that drilling out the holes on a non eyeletted rim (for example Ride Andra 40) would be a bad idea? Or would you say that it should be fine as long as you drill the holes carefully/make sure to deburr the edges etc. after drilling.?
The bike is a hardtail so the rear wheel does take considerable impacts when going over tree roots and such but it's held up quite well with my previous wheel (36 14g spokes, ryde andra 40 rim) thus far.(haven't broken any spokes since last wheel build with the andra 40 rim, only occasional truing was required). If you recommend drilling out the holes on a 'normal' (13g or 14g) rim, what rim would you recommend to start off with?

I thought about using a 26" motorcycle rim but unfortunately i have not yet been able to find any 26" motorcycle rims which are narrow enough to fit my current frame (width of frame where the rim passes in between chainstays is approx 57mm (so the max possible rim width would be approx 53mm), the max tire i can run is 2.4"

I can buy a rim from the same aliexpress seller where i bought the motor but the shipping is really expensive (75$shipping, 15$ for the rim itself, link to rim: https://jh-power.en.alibaba.com/product/1520548146-212266323/Power_P35D_26_Inch_Spoke_Rims_For_BMX_Bike.html) so i was wondering if there was a better alternative/where i could find a rim with these specs.

I don't care about the looks, any weight is fine (heavier is probably better since it might be stronger then), eyeletted holes would be a nice bonus, disc specific if possible.

Thank you !

 

[Balmorhea]

10 gauge spokes are far too thick for any bicycle rim. If they are tightened within spec for the rim, they’ll loosen continuously (and chafe the holes in the hub and rim, even if the nipples are glued in place). Their tendency to point load the rim will promote cracking at the rim holes. If you tighten them enough for the thickness of the spokes, you’ll pucker the spoke bed of the rim, or even buckle the rim entirely.

If you use a bicycle rim, 14 gauge (2.0mm) is the thickest spoke size that works correctly. Use 13-14ga single butted spokes if you must, though 14-15ga double butted spokes are better if you can get them in the correct length. Use washers underneath the spoke heads to take up the extra space in the hub flange holes.

26” bicycle rims are the same diameter as 22” motorcycle rims. The latter are very uncommon, but would usually fit in a disc braked MTB. 21” motorcycle rims are much more common, though they are divided between heavy street cruiser equipment and relatively lighter motocross types.

Motorcycle rims are, as you observe, much heavier than bicycle rims, but they’re not strong in proportion to how heavy they are. They are single walled channels, rather than tubular structures like high quality bicycle rims. Weight for weight, a double walled bicycle rim is much stronger.