Kabbage eBMX#1

K

Kabbage

100 W
Joined
May 19, 2012
Messages
105
Location
Melbourne, Australia
My nephew lives on an acerage just outside of town, and wanted a bike to get around the paddocks. He found this BMX on hard-rubbish and rescued it...

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Chain could do with some oil one decade. But cool - that top bar looks just the place to lob a 48V12Ah headway battery, doesn't it?

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Voila - we'll come up with a way to hold it there somehow.

Got BenMoore's last 'Code 9' fast wind 500W Bafang BPM. Tried it on Justin's ebike sim at ebikes.ca, and reckon it should be able to get to 35km/hr with 3+m/s/s acceleration with BM's 50A controller and 2-3C out of the battery. We'll see.

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Crazy colour scheme, but it'll go ok in the Red Alienation rim from CRC...

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And some nice (but short) 13G custom spokes from JRH.

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Buuuutttt... should have checked they would fit. Oops. My friendly wheel-builder had to drill out the rim *and* the hub so they would fit in. He finished building it today - so I collect tomorrow.
 
Awesome wheel and motor. Could you break down the battery and fit it in triangle? Would feel top heavy for a such a small bike up there?
 
2coupedup said:
Awesome wheel and motor. Could you break down the battery and fit it in triangle? Would feel top heavy for a such a small bike up there?
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Yeah, the battery is the one off my Avanti to see how it goes. I suspect you are right, it's going to be a bit high up there. I think the plan is to see how it goes, and if it goes well enough (to avoid said nephew wanting an 80cc trail bike, like the kids up the road), then we'll get a new battery kit and build something long and skinny, like I did for my the battery on my Scott commuter, or something to fit the triangle.

First things first, gotta get some oil on that chain... (and convince nephew to give the whole thing a good clean!)

Oh, the rim-tape, tube and tyre are now on. Also a 16T freewheel - some dodgey brand, LBS had run out of Shimano!



Actually, I was interested to see at the LBS, that many BMX's now have a free-hub/cassette arrangement which allows them to run miniscule xx/10 chainring/hub gear ratios - all aimed at getting the chainring down as small as possible - but dang those 10T free-hub/cassettes are tiny!
 
drew12345 said:
I like the color of the rim with the silver hub. Looks cool!
Click to expand...

Well, you know, I was going to get a black one, but they were out of stock - so I chose the red one as a "not quite what I want, but it'll have to do" solution. Turned out OK eh?

Same with the black/chrome hubmotor - it was the last Code 9 BenMoore had, so I wasn't in a position to argue that I'd prefer a straight black one...
 
Well here it is all put together....

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and a more detail view of the controller under the battery holder



The only minor problem is: It just won't go! arrrghghghg.
Not sure where the problem is yet, whether it is the motor is kaput, or controller not on or whathaveyou. Some annoying 'debuging' to ensue. Luckily I have a couple of other bits of kit connected to bikes I can try. I hooked it up to my Avanti's controller, and got nothing either - so suspecting it might be the motor - but perhaps my wiring is askew? Very annoying....

Another key finding, and something I hadn't bothered to check: the 'standard' BMX axle was way bigger than the axle on the BPM - and the dropouts are corresponding much bigger. Relying on the torque washers that came with the motors at this stage - but may need a proper torque arm...
 
UPDATE: It Lives!

Yay. I finally had a chance to swap out some bits and see what the problem was - turns out it is the controller not working, so I'll have to send it back to BMoore and see if he can make it work. In the meantime, I have got a new controller from Grin in Canada, and with a bit of re-termination, I have finally got it working.

There was still some fun along the way - when I plugged it in, the motor worked, but the wheel didn't turn - for a moment I thought the clutch was cactus - but then Ben reminded me that it was probably running backwards - which it was. The grin website says that the new 'autosensing' controllers can simply have a pair of phase leads swapped to change direction (and it will autosense the halls to suit). But this just didn't work I'm afraid - it either went ggrrrrggrrrrgrrr slowly in the right direction, or didn't work, or spun backwards. Took me a little while to work out how to find the 'reverse' cable from the controller - on my old grin controller there is a separate 2-pin JST which you short out. In the new one's it's not there - but it turns out if you read the back of the controller (it doesn't mention it on their website anywhere), you find out that you can strip back the shield on the throttle cable and there is a white and purple one unterminated underneath. You sort the white one to the black cable on the throttle and Robert's-your-parent's-sibling, it works!

Nephew is stoked. Goes pretty well. No speed measurements yet, but prob. 30km/hr.

The brakes are appalling. Worse than appalling, so I hope he sorts them out before he comes to grief. Perhaps new pads will sort that, but may need more.

Final photo:

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