BMX with MXUS

Relanium · Sep 20, 2016

So I was thinking for some time, but finaly decided to open up this thread

Specs:
- One used Haro BMX
- MXUS v1 (T4, upgraded phase wires)
- EM3EV's infineon 18 FET
- Turnigy 4S LiPos (20s2P)
- 16" moped wheels
- Avid BB7 brakes (203mm front, 180mm rear), a LOT of braking power and awesome brakes, easy to adjust

Base:
Haro BMX

Took it appart
Had to widen up the dropouts for 135mm motor
Heated them up and bent (steel is great

)

Made some CAD of reinforced dropouts and brake calipper holders, welded that on

And front

And then some paint job

Wheel building time

Front: MTH hub, Chrome wanadium solid axle, Sapim spokes and 16" moped rim

Used large 203mm rotor and stock BMX tire, it fits

(I planed to buy propper moped rims later)

And the rear one: MXUS v1 T4 with upgraded phase wires:

Laced into the same 16" moped rim with spokes from @madin88 (thanks :wink: ) (1x cross no problem)

Soo, wheels and brakes are on

Relanium · Sep 20, 2016

So then I just attached the controller under and had no idea how and where to put those LiPos on this small frame, so this is what I came up with:

I was making fiberglass side covers, but then just recently I sold the bike.
But it was a hell of a machine

https://www.youtube.com/watch?v=CLRRVrSKqNk
https://www.youtube.com/watch?v=tGY3Ym8aYFY

And once it threw me off...... paid too little respect to it

Anyway, my settings were: 42A battery and 80A phase.
But then this guy I sold bike to has pushed it to the max, the dude is crazy :!:

https://www.facebook.com/igor.tubic.9/videos/684224148400481/

Any questions?

skeetab5780 · Sep 20, 2016

Nice build! Good thing you sold it those speeds with those tiny BMX tires are dangerous with the weight of the motor and components added.

madin88 · Sep 20, 2016

What a crazy bike

the thrust must be great with such small wheel and 20s. no wonder it lifts the front that easy.
did you ever felt comfortable to accelerate to full speed?

Relanium said:
Anyway, my settings were: 42A battery and 80A phase.
But then this guy I sold bike to has pushed it to the max, the dude is crazy
https://www.facebook.com/igor.tubic.9/videos/684224148400481/

Any questions?

if he rides always like this he will kill himself one day! absolutely crazy

Relanium · Sep 20, 2016

Yeah, the torque is crazy, and on a straight road there's no problem accelerating to max speed (about 63km/h) with the settings I had.
Most of the time I rode it with a motorcycle helmet. Except the one time I didn't, and fell at about 40km/h.... ouch

That made me sell the bike in the end.
But it was fun as hell!

problemaddict · Oct 14, 2016

Hey man, this bike is awesome!

I've started in on a BMX build simply because that is the bike I had sitting around when I got bit by the ebike bug. As I progress, it looks like my bike will basically end up a bit of a clone of yours.

Could you give me specifics on your front hub setup? Does that Haro have a 10mm axle? My Giant Modem has 14mm axles and I'm having a helluva time sourcing a hub w/ disc mount that will work...

Thanks!

Voltron · Oct 14, 2016

They sell a BMX hub with 14mm axle and flip flop threading, that is, threaded on both sides, and they make an adaptor that threads on for the brake rotor. Not a great pic but here's one built up on my mid drive project.

Edit.. sorry.. Just realised you're talking about a front...

Relanium · Oct 15, 2016

problemaddict said:
Hey man, this bike is awesome!

I've started in on a BMX build simply because that is the bike I had sitting around when I got bit by the ebike bug. As I progress, it looks like my bike will basically end up a bit of a clone of yours.

Could you give me specifics on your front hub setup? Does that Haro have a 10mm axle? My Giant Modem has 14mm axles and I'm having a helluva time sourcing a hub w/ disc mount that will work...

Thanks!

Good question, it has 14mm axle and it got me thinking too.
First idea was to go with 20mm trough axle, so I would enlarge the holes. But I didn't know the system, had no axle (it comes with forks) and wasn't sure how it tightens up.
So I went with 10mm Shimano MTB hub (quick release) and kind of hoped I could fit 14mm axle to it.
That wasn't possible, so then I ordered 10mm solid Chrom-Molibden axle and made some adapters to 14mm
http://www.ebay.co.uk/itm/Weldtite-...618650?hash=item2cb2b2ba9a:g:CWMAAOSwCypWm~OF
Adapters look like 10-14 cylinder, thin washer inside, and I've kept original BMX 14mm hole washer outside (for obvious security reasons).
Could have definetly done it better, and machined out propper adapter, but it worked and I had zero problems with that setup. It's even crash tested

Sorry, no pic of complete setup, just this one
https://dl.dropboxusercontent.com/u/17505807/ES/ES_topic/2014-12-04 20.09.16.jpg

Relanium · Oct 15, 2016

This guy has it now
https://www.facebook.com/klemen.base/videos/677584905741146/

redline2097 · Oct 15, 2016

How much was overall diameter of backwheel (rim+wheel)?

Relanium · Oct 15, 2016

Same as BMX, 20"

(A bit over, I think)
16" moped rims are same diameter as bike 20"

problemaddict · Oct 15, 2016

Relanium said:
So I went with 10mm Shimano MTB hub (quick release) and kind of hoped I could fit 14mm axle to it.
That wasn't possible, so then I ordered 10mm solid Chrom-Molibden axle and made some adapters to 14mm
http://www.ebay.co.uk/itm/Weldtite-...618650?hash=item2cb2b2ba9a:g:CWMAAOSwCypWm~OF
Adapters look like 10-14 cylinder, thin washer inside, and I've kept original BMX 14mm hole washer outside (for obvious security reasons).
Could have definetly done it better, and machined out propper adapter, but it worked and I had zero problems with that setup. It's even crash tested

Thanks for the reply! So you made adapters like this:

Or something similar to this?:

teslanv · Oct 15, 2016

Sik build, Rel. Nice job.

My Green Haro BMX is pretty fun, even with a puny little 1000W MXUS. That think looks like a mini death bike. :twisted:

Relanium · Oct 16, 2016

problemaddict said:
Or something similar to this?:

Similar to this - in two parts actualy, a washer and a cylinder

I was searching for the first ones, but couldn't find them anywhere. They are probably much better option.

MrDude_1 · Oct 21, 2016

Relanium said:
This guy has it now
https://www.facebook.com/klemen.base/videos/677584905741146/

I love that he is riding it how it should be ridden... once he gets used to it, he should be able to ride a wheelie down the road. :lol:

so what was the max speed of this thing anyway? I was thinking of building a BMX bike myself, super simple looking, with the lipo in a backpack.

Relanium · Oct 23, 2016

Max speed when I had it was 64km/h, but now the guy claims he has managed to set it up to 120% Field weakening or something, and the bike went 70km/h.
And later he added a LiPo brick, probably runs 24s now. I don't know what's the max speed now.

problemaddict · Mar 27, 2017

Hey R.

Just wanted to say thanks for your info, inspiration, and answers to my questions. I've finally got the bike rolling! Check my progress here:

https://endless-sphere.com/forums/viewtopic.php?f=6&t=84157

I still have much to do to finish it up. Battery mounts, paint, wiring cleanup, etc...

BMX with MXUS

Relanium

10 W

Attachments

Relanium

10 W

Attachments

skeetab5780

1 MW

madin88

10 MW

Relanium

10 W

problemaddict

100 mW

Voltron

1 MW

Relanium

10 W

Relanium

10 W

redline2097

100 W

Relanium

10 W

problemaddict

100 mW

teslanv

1 MW

Relanium

10 W

MrDude_1

100 kW

Relanium

10 W

problemaddict

100 mW

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