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So...

I figured I would start this now whilst I've got some ideas in my head. Hopefully get some feedback and been able to finalise things in my head and start ordering material/getting stuff made.

I'm completely new to this so unsure of proper names of things so please excuse my descriptions.

Plan is...

  • Take the hub motor, and front wheel off my e bike and put it on a custom chopper style frame. These will be standard 26" hybrid tyres (a concern). I don't want big fat back wheel on this.
  • Long showy bike for summer use only.
  • I want to sit on it like it's a chopper.
  • Seat must be under height of back wheel.
  • Big rake. Front forks from wheel center to top of handlebars will be 5ft. Forks extend through head thingy up to handle bars all welded into one piece.
  • As minimalist as physically possible.
  • As light as possible without it folding up on me lol.
  • Floating saddle (basically minimum bracket visable
So far I'm looking at 30mm by 60mm by 2mm ss box for the frame. 30mm square 3mm ss box for the back arm. 30mm round 1.5mm for forks again ss which from reading on here will most likely be too small so probably look for 40mm round 1.5mm.

Nothing is set in stone really so if this sounds completely impossible then please be as brutal as you need to be. Lickle bit of constructive would be good as well though.

Here is a to size 2d mock up of basic shape and idea.
 

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I like it!

Seeing as you asked for guidance I have a little:

From personal experience 30mm with a 2mm wall should be fine for your forks, however with that amount of rake getting the trail right will make a huge difference to how nice it is to ride, I think you mentioned knowing someone who has experience with chopper motorbikes in your intro, so you may already know that, or they can explain it.

The frame design as you have it has a stress point in front of the rear wheel, it could just fold there when you sit on it the first time, if the tubing is strong enough it wont be an issue, but the other option is to run your top tube in a straight line to your rear axle splitting at the stays:

to play with.jpg


Looking forward to seeing more, sounds like a cool build!
 
Your drawing was the initial plan but thought if I increased the wall thickness it might counteract it. But reading lots of threads on here the joints are the issue. So wall thickness probably won't make any difference.

My only concern is seat height. I think your way will be the most practical though.

I know nothing about trail. Only what I have been reading in the forums. It seems lots of devout groups have there special numbers. I'll speak to pops in law and see what he says about it.

Thanks for the reply. Appreciate it
 
Ordered the bearings for head and crank today. Upon recommendation from pops in law. Tapered roller bearings
Screenshot_20170822-144906.png


Screenshot_20170822-145630.png

And these for crank. May need to order some different ones for this depends on how the cutting goes.
 

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Wow! Looking forward to seeing how you fit them up!
Do you have access to a lathe?

Fortunately yes. And a mill, pillar drill, marvel saw, etc. I'll take a pic of the machine shop. Easy stuff I can do. Harder stuff I'll get the machinist to do.

And even more fortunately a welding dept lol. 3 nuclear grade welders on hand 8 hours a day.
 
Tube for forks and crank ordered

Screenshot_20170823-105228_01_01.png

30mm x 2mm stainless for fork and head. 55mm x 4mm for crank.

Still unsure about attaching head to forks so gonna build em and decide when they're in front of me. Got an idea about making the head stem detachable from forks.
 
Bearings are in but no tube yet. Need to chase that up.

IMG_20170830_143529.jpg


These are for the crank. Do we think they're maybe a little oversize lol. Housing will be 70mm long and 60mm OD.

Then check these out for the head
15041045053611009632236.jpg

Beautiful. Almost wanna make the head transparent so can see these.

Crank housing is being machined early next week now.
 
IMG_20170830_160236.jpg


This is my initial thoughts for the head. The above drawing is full size of what I think brackets will be.

Bottom is a kind of exploded diagram. I'm thinking of making the shaft completely removable.

Only thing is this then means that all the strain will be on the screw. Would an M12 or M16 be strong enough?
 
M16 will be more than stout enough...if you have any worries, ditch the stainless and get 10.9 examples instead. The stainless should be fine, though.

Looks like a very, very cool project!
Jason
+1
 

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