Having done the mockup for the wheels and mounted the brake rotors and made a mockup for the rear sprocket adapter the next step is mounting the motor.

Since the frame is designed to fit a hub motor and we’re going to use mid-drive motors we need to figure out a good way to mount the motor on the frame. I’ve considered quite a few different positions for the motor but they all have drawbacks. I decided the best solution is to make a motor mount right in front of the rear wheel, making the shortest possible chain line while still keeping the motor as close to the pivot as possible as to limit the unsprung mass momentum of the bike. The tricky part is that this is where the rear shock sits.. So I started by mounting the 200mm shock I’ve got and made the bike sit in the fully extended position on the bench. I then removed the shock, cut the lower shock mounts off and did some measuring.. The CAD turned out like this.

There is going to be a bracket on the left side of the motor too but as of now I’m not sure wether to simply make a motor/shock bracket or to make a new custom endcap for the motor. The right bracket prototype is being printed right now and I’ll use that to check more clearances and get a better feel for the solution. In the CAD I’ve moved the shock all the way to the right to limit the forces on the M8 bolt that holds the shock but where it’s going to go is not yet decided. The upper mount might screw right into the frame or I’ll make it a part of the seat.

I’m going to try to make this modification without welding anything to the frame so it’ll be easier to reproduce if anyone else wants to build a similar “bike”.

TBC..