Bobber style scratch build

I decided it was time for a new bike, this will be my sixth build, my forth with a custom frame. I wanted to build the entire bike this time, including the forks/handlebars as well. This will be my most ambitious build to date. Staying within a limited budget I opted for the Magic Pie 2, 24" x 65mm wide double wall rims, Kenda Kraze tires, 8" discs (which will be matching) with Avid BB7 calipers.


Central section of fork is done, used thrust bearings on either side of the main pivot. I devised a clamping system to attach my own bars.


Fork legs finished after a bit of weld clean up. As I don't have facility to do TIG I opted to ground things smooth.


The finished fork compared to the somewhat less beefy Schwinn style inspiration.


As the fork will have covered drop outs/pivots, I decided on a similar treatment for the rear. You can do a lot with an angle grinder, drill and files.


Mocking things for size/clearances in my uni-strut jig. It's not laser straight but really helps to keep things in alignment.


Forming the lower chain stays


First time sitting on it's wheels, mocking up the seat position.


Battery/controller rack built. To power the lights there's a mount for the DC-DC converter under the Controller. I've opted for a Greentime 3000 watt, 80 amp controller with a 48 volt, 30 amp/hr battery made from Samsung 18650 cells.


Here it's shown with second attempt seat mount as the first style didn't flow as I wanted. Discovered that my air shock was too dampened (non adjustable) so changed it out for a small coil spring style.

looks very cool. Not my style of motorcycle, but I sure can respect the time it takes to build it that nice.

yes. motorcycle.

Just because you're putting pedals on it and a smaller motor, doesnt mean its any less of a motorcycle. :lol:
Keep at it and keep the photos up. I look forward to seeing this come along.

Thanks (Mr) Dude! When you build for yourself, you can build any style that appeals to you. I like to think of it as a motorcycle styled motoped rather than e-bicycle, it's not pretending to be anything else. Having pedals means I don't have to insure it, plus it'll have enough zip to keep up with city traffic. I'll have the coolest commuter in the bike room at work

Bottom bracket detail:


Rear light mounted:


Handlebars, CA and headlight mounts done, will need to have a final trim to width:


Controls and rear fender mocked up:

The radius of the wooden fenders will be a little tighter to the tire and without the flat spot at the end.

Excellent frame,i dig it . i like the side plates on the BB - crank will keep it nice and stable.

beast775 said:

Excellent frame,i dig it . i like the side plates on the BB - crank will keep it nice and stable.

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It would be a lot more stable welded on a stub of tubing. Better yet would be to intersect it with the main frame tube. An X-shaped cross section like that has poor torsional rigidity.

I agree a fish mouthed piece of round tube would be stronger. It certainly would have been easier to do but wouldn't look half as kool. I don't expect to snap it off any time soon but if it happens, feel free to say "I told ya so...". I'm glad you like my bike enough to criticise it. :wink:

WOW, all done in less than 12 hours?

As I said WOW, that is one mean looking machine.
How long did it really take?

Dan

Minutes to upload, weeks to build.

Nit pick it a bit much? Really? he's going to pedal it so hard that bb mount flexes? I rather doubt that. And it's not a motorcycle, if it's top speed is legal where he lives. It IS a really overbuilt bicycle though. Looks ready for 10,000w on a smooth racetrack.

Beautiful work. I like the fork for sure.

I'd like to see more about how you bent the tubes. I have a crude conduit bender, but it's only good for simple stuff, and only one radius.

What i really meant was, better than just a single thin bracket as shown that alot of chopper frames have. An X-shaped cross section like that has poor torsional rigidity, not if you know how to weld and use fat bars and understand how much torque you are using....

Dan, I use a JD model 32 bender. It's more than strong enough to bend virtually any tube with ease and has dies from 1" to 2"+.


As I will be running 48 volts the top speed will be limited to about 54 km/h for this build which is illegally fast where I live (500 watts @ 32 km/h, but who cares?). I too believe the frame would withstand 10k watts, but this is a warm up to the next build which will have a QS v3 50h, 60 or 72 volts and fat motorcycle tires. As the bottom tube is 1.5" x 1/8" wall and the BB is supported by 1/4" plate I find it laughable that any one would be overly concerned about a 170lb guy flexing the mount in those first 3 pedal revolutions when leaving from a standing start. Those Voltage frames are nice but look top heavy to me with the pack in the tank position and empty below, but they do seem to manage without any extra supports on the BB mount. 8)

dogman dan said:

Nit pick it a bit much? Really? he's going to pedal it so hard that bb mount flexes? I rather doubt that.

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If I was nitpicking anything, it was the other comment that the BB would be nice and stable.

It is a nice looking weldment. So that's one out of two.

I am always the most impressed with the custom ebikes that are built by the owner. I have enjoyed looking at custom cars at car shows, but....sometimes they are owned by a rich guy who just paid a guy to make what he wanted (so, tell me what the latest trend is so I can pay for one of those, except more expensive!).

The great thing about showing off techniques for frame-building is...everyone has their preferences, and we each can learn to build our own frame, to highlight the best possible version of an ebike that captures our individual philosophy.

The kickstand is the part I usually skip on a build and then regret later as I'm searching for somewhere to lean the bike against.


Lugs welded into position and lower frame tube capped.


Fairly stealthy when folded up. Need to add a return spring and make some feet for the ends.


More stable than a side stand when deployed.


I bought this handy freewheel spacer online, an easy fix to straighten out the fat-tired chainline.

8) Too cool.

Are you using 16ga tubing? The bends look really good.

I have that exact same tubing bender. It works great. You may want to look at the swag off-road conversion kit for making it hydraulic. Uses harbor freight cylinder.

Finished the centre stand today:

Ahh, knew you had something nice to bend the tubes. I've just been thinking about plywood, home made radiuses on a stout table.

Gonna have to tool up I guess.

Decided to add a forkstop to the build. Used a suspension snubber and tapped a disc for the 3/8" mounting stud, should save some wear and tear on the cables.




I wasn't completely satisfied with the centre stand so I spent a bit more time on it. It has a much cleaner look to it now and the double springs make sure it stays retracted while I'm riding.

Nice!!!

Frame is awesome, if you consider selling one let me know. I would buy one for the right price.
I want a similar frame to build an actual motorcycle.

Although don't let people tell you this is one, motorcycles start at 8000 watts. The motor (engine) defines it.
Remember all the first Harley Davidsons had pedals and tiny motors.

Samd said:

Although don't let people tell you this is one, motorcycles start at 8000 watts. The motor (engine) defines it.
Remember all the first Harley Davidsons had pedals and tiny motors.

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Speaking of Harleys, I think this one's a motorcycle. It had less than 5000 watts of power. But its engine wasn't exactly tiny at 800cc:

I tried hard to build a legal e-bike greater than 500 watts, even spent considerable time on the phone with the government run insurance corporation and made my case for an e-bike over the 500 watt limit built from quality parts. I would be very happy to insure one as a limited speed motorcycle, a moped or anything acceptable to Canadian law. I was told no matter what I did, no matter whether I used downhill mtb brakes, rims, suspension, etc, if it wasn't made entirely of Transport Canada approved motorcycle parts and welded by a certified welder, it would never be more than an illegally motorized bicycle and not insurable. In the eyes of Canadian law if it's 501 watts it's just as illegal as if it's 10k watts.