eMTB build - MBS Pro 12

Lightweight / Folding / Portable EVs - seats optional
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benj   100 W

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eMTB build - MBS Pro 12

Post by benj » Apr 22 2015 5:24am

Hey everyone, time for another project :mrgreen:

I got hold of a cheap MBS Pro 12 Jeremey Leafe edition and so naturally - wanted to make it electric! It has nice Matrix Lite channel trucks - the ones with the brake adapter threaded hole.

My disclaimer...I am not an engineer, I have no previous metal work experience, no fancy tools, and not much natural skill with dirty/hands-on work...but I love to try :D My previous builds have been using kits, or calling in favours, and this time I wanted to do it all myself.

Hopefully this thread will inspire people like me to give it a go, and people will be generous in their comments and won't bitch on me for making a conversion that looks like my dog chewed it ;)

So - the donor board and trucks:

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I was very inspired by these two builds, I suggest you check them out as well!

Inspiration
vlaca2 - MBS Pro 12 (exact same board!) - great low-tech solution
http://endless-sphere.com/forums/viewto ... 35&t=68710

nowind - Trampa - nice clamping system
http://endless-sphere.com/forums/viewto ... 0&start=25

Gearing
Because of my low skill set, I'm attempting a low-tech solution! I was worried about making an adaptor plate for the MBS wheels, so I decided to get a big enough sprocket that didn't require an adaptor plate:

- I went for a 50 tooth platewheel sprocket, because it had a big enough diameter to span across the exisiting bolts that hold the MBS wheel together
- I went for a 20 tooth pulley, to give me a 2.5/1 ratio
- ISO 08B1 chain - 6mm pitch
- On 6S that should give me just under 20mph real world top speed

Here's how the mounted sprocket turned out. I basically replaced the hex bolts that hold the wheel together with longer ones, and used nuts as spacers.

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The mount
I wanted to try some metal work, so I went for the clamp style mount. I found some 6mm 6082 aluminium on ebay about the right size and started drilling holes in it :) I used the hardware from my motor to get the holes in the right place...and then my goldfish chewed the hole in the middle for the trucks ;) Haha.

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The square hole was carefully cut to fit really snug against the trucks The rounded parts are where I drilled a hole to get my hacksaw blade into the metal, then I could cut corner to corner. I also drilled a bevel into the motor bolt holes so that the heads sank lower into the plate. I then shelled out for a tap and die set to thread some holes, cut across the square cutout, and went for it....here's how that turned out:

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I made a mistake here, I should've drilled down through the sides of the bracket before I cut across because it came out a bit wonky!! But close enough! I must find some hex bolts to replace those screw head bolts....

Putting it together
Things seem to be going quite well, and the chain looks like it aligns OK so it was time to break the chain and put it on. I used a simple nut and flattened screw to bash out a pin on the chain. Just rest the link on top of the nut and drive that pin out. I did a practice run first and learnt a few lessons. After that - it went well and the chain fits nicely:

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So here's the hardware all together. The wheel, chain and motor run pretty smoothly by hand. Will try and power it up gently on the bench and see what wobbles!

Next steps
I'll put some electronics near this and spin up that motor. I'm sure it will reveal problems and issues. If it all looks good then it could be close to riding off into the sunset with a big EV grin :mrgreen:

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vlaca2   10 W

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Re: eMTB build - MBS Pro 12

Post by vlaca2 » Apr 22 2015 6:19am

Wohoo, another pro 12! :)
(Yours with alu hubs, coool!)

One motor or two?
Middrive hardtail e-bike build: https://endless-sphere.com/forums/viewt ... 28&t=91875
Scrub Psycho e-mtb build: viewtopic.php?f=35&t=66244
MBS Pro 12 e-mtb build: viewtopic.php?f=35&t=68710
Electric Drift Trike build: https://endless-sphere.com/forums/viewt ... 35&t=84936

furp   100 W

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Location: Germany

Re: eMTB build - MBS Pro 12

Post by furp » Apr 22 2015 6:29am

Nice to see I am not the only one limited to a hacksaw for 'machining'! Turned out nice!

How did you get the wheel sprocket centric? That was the bigger problem of my build. I used the same method of attaching the sprocket to the wheel, just used all 5 bolts (got plastic rims tho) and it is still running like a charm!

On my MTB I used a similar 6mm aluminum plate but a seperate thicker block for clamping which the plate is attached to. That added lots of bolts and complications, but I was afraid that the 6mm clamping surface and the thin bolts that go through it might not hold the power of the motor pulling the mount sideways. If you get a problem with that, maybe just add a mounting point to the brake bolt hole in the axle. Or add a 2nd motor and link the two mounts so the forces counteract each other.

You will definately get a big Rv grin, especially when you go from normal clean roads to rougher ones and trough mud :)

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benj   100 W

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Re: eMTB build - MBS Pro 12

Post by benj » Apr 22 2015 7:50am

@vlaca2 - one motor for now, I will only try 2 if I feel it needs the extra power. No need to waste money if I'm happy with 1

@furp - thanks. Hacksawing is not much fun, but it turned out OK. To get the sprocket centered I used a long 10mm bolt, luckily my sprocket came with a 10mm bored hole, so the long bolt went through the wheels 10mm hole, then the sprockets, so I knew they were aligned perfectly. I then used a long screwdriver through the wheels bolt holes to make marks on the sprocket. There was probably a better way, but that's how my crazy brain solved it!

Yes I am worried about the 6mm surface area for the clamping force. I like the idea of adding a brace using the brake bolt hole :) Thanks!

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LEVer   10 kW

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Re: eMTB build - MBS Pro 12

Post by LEVer » Apr 22 2015 10:43am

Looks nice. I second furp's comment, mount an L-bracket and use the brake holes to secure the mount more. Then a rod to another mount on the other side of the truck. Use strong and solid plastic rod to avoid eddy currents.

The mount looks quite thin and long, and will probably flex causing the chains to come off. It actually looks like you can even shorten the mounts to make it closer to the motor and have lesser flex.

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benj   100 W

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Re: eMTB build - MBS Pro 12

Post by benj » Apr 23 2015 6:03am

It moves! First gentle ride today, it went pretty well. The mount came loose after about 10 minutes, so going to add an extra brace for sure using the brake mounting hole.

The gearing seems good though, and although I was gentle got some OK speed. I think my estimated 20mph will be about right :) I ran this on 5S and hit 14mph easily....



@pediglide - yes the mount is long, I wanted to make sure the motor shaft didn't foul the tyre, so played it safe. I could take off 20mm for sure, maybe more. I might also consider 8mm or 10mm thick next time as well.

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benj   100 W

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Re: eMTB build - MBS Pro 12

Post by benj » May 13 2015 7:46am

Had some great fun on this board today. I found an old Motorcross track near me so thought I'd give it a try.

Hard work. Very loose dirt, the board kept digging itself into a hole, and it was so soft and deep that my 1 wheel drive had no chance! Still, it was fun dropping in from rollers and trying to power slide round corners :D

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My mount help up fine, must've done about 10k on it now without a problem :) But I want 2 wheel drive!

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vlaca2   10 W

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Location: Hungary

Re: eMTB build - MBS Pro 12

Post by vlaca2 » May 13 2015 8:16am

Coool track! Please make video!! :)
Middrive hardtail e-bike build: https://endless-sphere.com/forums/viewt ... 28&t=91875
Scrub Psycho e-mtb build: viewtopic.php?f=35&t=66244
MBS Pro 12 e-mtb build: viewtopic.php?f=35&t=68710
Electric Drift Trike build: https://endless-sphere.com/forums/viewt ... 35&t=84936

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