Brodie's electric board track bike

Brodie

Gold Coast, Queensland
DTT SUPPORTER
After being given an old 36v front hub electric bike with a dead battery I was struck with a bit of inspiration.

The old bike was used to build a normal bike for my son who is now enjoying all the freedom of having a mode of transport.

I then begun collecting parts for my build and researching electric bike parts.

My inspiration for the build is the old motorcycles from 100 years ago. The like of the early Harley and Indians racers along with a few AJS, Norton and of course BSA bikes from the turn of the last century.

A bicycle with a motor is still a motorbike right?

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Brodie

Gold Coast, Queensland
DTT SUPPORTER
So I began by searching for the right frame to use. I had an idea in my head what I wanted and just waiting watching the local classifieds until something came up.

I found one about 40mins away and while it was not perfect for what I needed it was close enough.
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I then proceeded to pull off all the unnecessary parts and fit a few things I had collected. A springer front end was a must for this.

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The bars and neck were only on there as a dummy to allow me to move the frame where I needed. I cut the upper frame tube out and began to clean up the frame. As this is an older frame sections were brazed in and I was able to remove the inner section I had cut from the neck leaving me a perfect socket to hold the tube while I played with fitment.
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Coming together but still not quite right. The wider rear tyres I am using need a little clearance done for the frame.
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I managed to pick up a nexus 3 speed hub when I got the springer front end. Not that I plan to pedal too much on this but it might come in handy to save battery power.

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Yep that is the angle and rake I was after. Need to modify the seat post to get the seat further back over the wheel.
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
I then turned my attention to the power side of the build.
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From all the research I have done it looks like I will need to beef up the forks a good portion to be able to handle the power of the hub motor.
I am planning to run a 48v battery that has an output of 30a. The controller I have bought is a 18 fet 22a continuous output sine wave. So I plan to run the motor at 48v by 21a for a 1008w system.
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Currently the motor is with my Father-in-law who was keen to help. He is going to rebuild the wheel with new spokes and true the rim.

The battery is due for delivery tomorrow with the rest of the parts arriving late June. Stay tuned for more.
 

pidjones

Over 1,000 Posts
Watching expectedly. The board track racers at Wheels Through Time museum are my favorites.
 

ridesolo

“Kto ne riskuet, ne pyot champanskoye.”
DTT SUPPORTER
DTT BOTM WINNER
Really fun concept. I need to watch this.
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Sure is interesting working on a bicycle as a base.
Everything seems so fragile.

Had a go at changing the seat post to better suit the style.
Had one of the boys at work cut the post at a 45° and then re-weld it. While it looks quite good I wasn't sure if it would hold my weight.

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The answer was no. It bent slightly as I went to sit on the seat.
Looks like I will need to add a gusset. But I am not sure if the tube wall is thick enough even with a gusset.

Also threw some paint on to protect the bare metal. Not sure if that is the colour I want to go with. Thinking primer red might be a better choice.
 

gt alex

Been Around the Block
Great idea, my vote is try to copy the style of the harley you posted with the u frame. you could make a u frame
(a pleasing design that is strong and has simple elegance to the eye) attaching the front, rear, seat to that .
Looking forward to what you come up with
 

Jimbonaut

Over 1,000 Posts
DTT SUPPORTER
So cool, love this. My friend's 12 year old son is really interested in engines and the like so me and another friend are going to build with him his choice of death machine this summer, either a go kart or motorized bicycle. I'm on engine duty, my mate's going to be fabbing the go kart frame or hauling out a bike frame from his large stash. I'll be watching your build Brodie - inspirational and educational stuff. Love that springer front end
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Not a lot of progress over the past few weeks. Still waiting for parts. The new bars turned up which is good.
I need to modify some of the connections from the controller to the motor and from the throttle and brake levers to the controller. Looks like the controller I bought if from a newer source to the levers and throttle as it has smaller connections.

Still deciding what to do about the front end. While reinforcing this one and painting it was the initial plan I feel that the continued use of 1000w motor is likely to bend the squashed tube open and it will be an ongoing headache.

More to come soon.
 

Rat_ranger

Coast to Coast
I've wanted to do something similar for a while. All based on the fact that I have a harley 125 girder fork in my stash. Except I was thinking cb125/xr200 or xr100 motor instead of electric. But I'm interested in reading more on electric conversions.
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Go for it I say.
Would be cool to see the forks. This whole idea started from having "all the kit" needed. Course it was old and needed to be upgraded or replaced so all I really had was the motor.
I like the idea of a small cc single as the engine.

I strengthened the forks today. Going to give the pressed tube springers a crack and see how they go. I have doubled the width of the axle plate so hopefully that will handle the power.
No pictures yet until I clean up my janky arse welds.

My father in law has told me that he has the spokes now so will begin rebuilding the front wheel.
 

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