Motorized Bicycle Wide Crank Set CVT
Customer Build with https://mbrebel.com/product/13inch-span-square-taper-crank-axle-kit-american-bearings/
We are not able to answer detailed questions about this bike, we did not build this bike at
MBRebel, please see pictures.
I decided to build two of these with my own design frame, tank and fork,
using a four stroke Continental 1A08 military genset engine.
The first pic shows the “secret”… Using your wide pedal crank setup,
with my modified comet CVT pulley / custom drive sprocket.
This keeps the drive train low in the bike, and super clean.
I used your wide crankset, and the keyed sprocket adapter that fits it, and re-worked a
comet CVT to freely spin on the pedal crank shaft, using it as a jackshaft.
This works great, as these engines are 131cc, rated at continuous 1.5 HP
(actual HP with 19MM Mikuni carb and shaved head is probably 4.5-5…ish)
Top speed is about 50 MPH, and will do that all day long , just hold it wide open and cruise !!
I did a 100 mile ride on this bike, and it was a breeze.
The rear hub is one I machined from scratch for the disc brake and HD sprocket setup.
Rims are 65mm wide Orign8 fat bike rims, with 26×4.0 Origin8 Supercell tires.
These tires are BY FAR the BEST fat bike tires EVER !!!!
Vintage looks and a rounder profile than any other fat bike tire = better handling.
These tires are available in two versions : A heavy wire bead version, and a light folding bead version.
Feel free to use any and all of the pictures of my bike , as all bikes,
from the simplest to the most elaborate , are mechanical art, and they inspire others to
build their own.
A couple more pics show the rear fender and tank mounting.
The fenders I started with are repop early Harley Sportster frronts.
I rolled them out a bit to fit the larger diameter wheels,
and cut + welded two together to make the full rear fender.
As you can see, I love the metal working aspects.
These first two pictures are of the little hollow shaft sprocket
I made to press into a standard Comet 20 series torque converter.
This hollow shaft sprocket holds a sealed bearing inside the sprocket,
and visible in the second picture is the only mod I did to the Comet pulley to fit the other bearing.
I did this so I could run this pulley on the pedal crank shaft,
rotating freely on it, and driving the rear wheel through the left side chain.
The 20 series driven pulley has a big advantage over the more generic
“torque averter” kits most people see and use.
That advantage is that it mounts with the cam hub inward,
making the setup about 2″ narrower.
This makes for a very tidy installation,
much narrower and cleaner than any torque converter setup I have seen used on a M.B.
The first picture shows the unit just before sliding it onto your shaft, which
I turned down to fit the bearings inside the hollow sprocket shaft.
The second picture shows how it nests in behind the Engine.
The two bikes I’m building right now with this engine/torque converter setup
are a bit more sophisticated than the similar era-styled Helmutt bikes.
I didn’t copy any other bike when I built these frames,
I just love the late 1920’s – early 1940’s period of style.
Fenders are spliced together early Harley sportster fronts,
and they fit the 26×4.0 fat tires perfect after I stretched them out, working them a bit.
The Fuel tanks are stressed members of the frame, and hold about 2 gallons.
The second picture shows the RH side of the drive train, with the exposed flywheel……rope start!!
The bikes have stout center stands, so no problems there.
I don’t have the rear sprocket / one way roller clutch installed on the custom rear hub in these pics,
but this setup allows drag – free coasting and pedalling.
Again, your efforts at offering hardware for all kinds of bike builds is much appreciated !!!
I have made so much of these bikes by hand,
it’s nice to find nice off-the-shelf parts every once in a while!!