Project chopper

Joined
Dec 29, 2016
Messages
255
Location
Lanc's, England
Hi Brad
The rear hub is a shimano 8 gear with coaster brake.
The e-hub ,350W, will be in the front wheel.
I will have a disc brake on the front wheel, my worry is if the coaster brake is strong enough or should I dubble it up with a disc brake?
My first design was no e-hub and only coaster brake, so there was no need for brake handles, but with e-hub I need the disc up front.
I also like the fork to be simple to remove for easier transport. So I want minimal cables between fork and frame and they should be easy to disconnect.
 
Joined
Sep 16, 2018
Messages
414
Location
Netherlands
I couldn't find the video I wanted, but it is a bit similar to this.

I didn't know that they are popular, but it seems they are. There was a big meet-up in the Netherlands with those bikes.
 
Joined
Dec 29, 2016
Messages
255
Location
Lanc's, England
The rear triangle is my first part to assemble.
To finish the tube joining the rear dropout I tried to make the ends into bullet shape.



I cut a small piece of 1/2" tube, cut some notches into one end and hammered the end into a bullet shape.
The 1/2" tube fits inside the 5/8" tube giving me a thicker tube to weld the dropouts to. After some welding and grinding I got some sort of bullet shape.
I also cut out on the inside of the tube so the dropout plate can be welded flush with the inside of the tube.



So this is the finished bottom half.
I found may first mistake, the U bends is 135mm on the inside, the same measurement as the rear hub.
But the rear hubs is about 5mm off centre on the drive side, so I get a 5mm larger gap on the drive side between frame and tire.
I should have made the u bend 130mm and bend the tube outwards on the drive side.
I don't think anybody will notice when the chain is fitted, but I will.
I decided to make the rear dropouts horizontal. The Shimano gear hub has a washer on each side which decide where the gear shift cable will enter the gear hub.
If you look at the rear side of the hub in the picture above, there is a black tube sticking straight up with a circle on top, thats where the gear shift cable goes.
I rather have it follow the frame.
The washer looks like this.




So I'm tempted to make one where the hole and the key are in the correct position so the cable entry will be parallel with the frame.
 

SirJoey

Super Moderator
Joined
Feb 8, 2008
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My cozy little nook in the corner!
Man, I'm likin' those bullets!
That looks great! Nice custom work! (y)
It's little details like that, that make one look professional!
***
 
Joined
Dec 29, 2016
Messages
255
Location
Lanc's, England
The rear part of the frame are now ready for welding.



Decided to finish this part before adding the rest of the frame,
but that includes figure out a way to run the gear cable inside the frame,
and fit a rear light.
 
Joined
Dec 29, 2016
Messages
255
Location
Lanc's, England
The rear frame is now fully welded and 75% finished.
So my next step is to complete the frame.
When I made my muck up I realised that the tube on the bottom was about 100mm to long.
Turns out that I miscalculated the angel of the bend with 10 deg, so I hade to re cap the tubes and re-bend them.
So the muck up went from this.

to this


Now it's more like my drawings.
The first bend would make the pedals to far forwards from the frame.
I'm not to pleased with the bends but it will do.
The top tube consist of a short piece of 22 mm tube with a 7 deg bend and then a 25mm tube.
So now I can fit and adjust a standard seat clamp along the 22mm tube.
To make the seats angle bit more comfortable I bought a seat spring, which also gives me more adjustment for the seat.
If the seat don't hit the frame, the seat clamp will be flipped to make the seat lower.
I will fill the sides behind the stearing tube in a chopperish style to strengten the frame and it will also conceal the motor controller.
So next, find the stearing tube and tack it all together.
 
Joined
Dec 29, 2016
Messages
255
Location
Lanc's, England
I decided to hide all the cables in the tubes.
So not to weaken the frame I'm welding insert into the frame for the cables to run through.


This will be under the battery for the power cable to run to the controller.
The coiled wire is so I can pull through the copper cable.
And the other side.



And in the other tube the cable from the pedals to the controller will go
It's a much bigger connector so it needed a large hole.



I checked and dubble checked before I made the hole and welded in the insert
but of course I cut the hole in the wrong side.
My first thought was to make new tubes, I never liked the bends anyway, but I only have enough tube for one side left.
So out come the grinder and I cut away the bends so I can turn the wire entry point in the right direction.
And I also made some new bends, one good and one ok, but still better than my first ones.



I also realised how much easier it will be to assembly the rest of the frame when I have more pieces to work with.
I have, more than once, tried to weld the front part of the frame to the head tube, but before I got the right angels to all the tubes something always moved.
Now I can do it in steps. First the under frame.



With crossovers for the battery pack
And this how it will look

 
Last edited:
Joined
Dec 29, 2016
Messages
255
Location
Lanc's, England
I have for a long time tried to shape the ends of the lower tubes into bullet points and wrap them around the head tube and at the same time keep the head tube in it's correct position. I got one side tacked to the head tube but it never looked alright.



So I left it and started to ponder over the infill plates behind the head tube and I soon realised that the bullet ends would never work, it would interfere with the infill plates, so out with the cutter and of with the bullet ends.
And now it was much easier to attache the rest of the tubes to the head tube and tack all the welds of the frame for now.
So I couldn't wait for the first total mock up



I also started the fork but more about that later.
 
Joined
Sep 12, 2012
Messages
2,869
Location
Apple Valley, California, USA
I'm assuming by 'infill' plates you are referring to the gussets behind the head tube.

I think you have a unique style idea there with the bullet ends.

If I understand your desired bullet end idea...
I've drawn up an idea for you to consider that might make your idea a reality.
The angles aren't correct for the bike, but the design idea for the gusset is there.
 
Last edited:
Joined
Dec 29, 2016
Messages
255
Location
Lanc's, England
The gusset will also hide the motor controller and is the hub for all the cables.
The lower part of the frame is wider than the head tube, to allow room for the controller,
and the gusset must be flush with the outside of the frame.
Anyway the bullets are gone.
 
Joined
Dec 29, 2016
Messages
255
Location
Lanc's, England
The progress has been slow, so it time to get the project into full speed again.

Next in line is the gear shifter, it will be situated under the seat, my plan was to use the right hand for shifting, but when I checked how the cable runs,
I changed it to a the left.
In my scrap pile I found a piece of bent 22mm tube from a failed handle bar for the phyton.



I welded the tube to one off the uprights under the seat and fitted the gear changer



Next is to get the gear change cable to the rear hub
 
Joined
Dec 29, 2016
Messages
255
Location
Lanc's, England
My plan was to fix the controll unit behind the head tube
so I welded a fixing bracket across the lower tubes.


And cut up a trial gusset to cover from some scrap.



Hmm, It's very large, not the look I wanted.
What shall I do?
 
Joined
Dec 29, 2016
Messages
255
Location
Lanc's, England
I went to my workshop, after I posted above, and with a markingpen and a cutting disc
reshaped the gusset



Getting there, I will mount the controller exposed under the tubes insteed and only have the cable harness under the gusset.
It also helps with the cooling which I was worried about.
Not what I wanted but I can't see another way.
 
Joined
Oct 19, 2012
Messages
1,018
Location
Wakefield, UK
Would it not fit under the seat? I see your difficulty. A chopper should be as simple and clean as possible or at least convey that impression. Looks are everything. What about inside a headlight unit or a skull style bikini fairing? What about a suicide shifter for the gears? I had one on a 3 speed hub based on a twist grip not dissimilar to yours.
 
Joined
Dec 29, 2016
Messages
255
Location
Lanc's, England
Hi Popshot,
Because the hubmotor is on the front wheel, a god place for the controls unit is around the head tube.
I also like to be able to remove the fork for transport, without having to many cables to brake.
So having the controls close to the head tube make that possibly.
I also have a BB torque sensor and the original cable would not reach the seat.
Suicide gear shifter, I did consider that, but I have a 8 gear shifter and the angle different between 1 and 8 is to big, so it will stay under the seat, for now.
 
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