REV_2 DIY E-MTB Outrunner front mount

Dear All

Have been working on this for some time. Think 2. revision is getting ready for testing. Just wanted to share some progress. When tested and ready for DIY, I plan to sell the design/print files for a modest $, maybe inject-mold the gears at some point. “Gear Box” will be fully sealed, to avoid dust and grime from messing with gears and grease.

Have a 26 inch MTB I plan to mount it to

The design is intended to work with these (sensored) BLDC´s

GT3 5mm pitch belts 9mm wide. GT3 is a improvement compared to HTD5

Im ready to print Nylon :smiley:

Gears will rotate on 3x 626ZZ bearings (6mm bore).

Stay tuned

Have sketched up a tension bracket for the belt. This way, it is more straightforward to take off the belt, when and if the bike runs out of power. It will of course also insure a tight belt.

I found that we need a 665mm belt, which is 8.5 euro on Misumi

Trimmed down the design. Ready for laser cutter (2mm stainless)

Previous design was 93g (filament) this is 73g. Cutting print time with almost an hour. (same print setting).

Just picked up the laser cut stainless steel top lid/ motor mount. MOW (Makers of the World).

63mm outrunners are on the way with Fedex :smiley:

Opted for GT4 8mm (pitch) 12mm (width) belt´s. They should have a 25% improved load capacity compared to GT3. Furthermore the 12mm compared to 9mm will increase performance. There is a open question though. Gates advises to use a minimum of 22 grooves for pulley. I will use 14, but because the tensioner / idler compresses the belt around the teeth, I suppose the contact of groves will be close to a larger pulley without idler. I do not see the belt slipping on those large teeth/grooves. Do you think the belt will have a hard time to bend around 14 tooth pulley. Overall gear-ratio will be 1 : 10.8. Im going for a slight increase in top speed at the expense of acceleration (140 kv). The normal use case will not come close to the belt´s load capacity.

Edid: On a 29 inch wheel I think a 200mm disc is more suitable compared to the 180mm im working on. This will most likely even out the difference in wheel size vs. gear-ratio. Some front forks are build for 200mm disc´s, while some need a spacer.


A cat walked by, then the same cat walked by… Usually it happens when something is changed in the MATRIX

Just received the Optibelt Deltachain. Feels rugged.

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That sounds $$$ ! Can’t buy these where I live, even if I had the money :slight_smile:

Ordering such parts is expensive for sure, but that’s what MakerSpaces are for :smiley:
Sheet steel isn’t that expensive…

I dont know the final price. When the concept i ready, I will do a Kickstarter. Making a community order will cut the price. I payed around 100 for two pcs at my local CO2 laser cutter. If ordering from a industrial supplier I think the price might come down to 20-30$ a peace.

Making the gear housing in aluminium, that’s another matter. This would require a tool/mold and large quantities. I believe a 3D print can be strong enough. PLA will warp in the heat though, and nylon is hard to print. PETG is a good candidate.

[Edit] I plan to mount the plate to my openPnP machine, and run it on 24v psu. Need to get a hold of some magnetic angle sensors for that.

But if you have a top and bottom plate in steel, couldn’t you mount the gears to that using some bolts, bushings and bearings? Those parts are available pre-made and cheaply, and then you would not need a mold?

What I meant was, if you want to inject cast the box in aluminum, it’s expensive. Or you can CNC it. Was just thinking how to scale it. The top plate will hold the drivetrain axis, so it should be strong.