Modifying Friction Drive To Accept GEBE components

Trying to recycle friction drive kit to accept GEBE parts.

I'm modifying two BMP/Staton friction drive kits to make "better mousetraps".

My first DIY project involves leaving my FRONT friction drive housing in place, relocating the engine, using the BMP axle as a jackshaft and installing chains and sprockets. Engine gets a 5:1 gearbox and relocates atop the friction drive housing. That project is pretty straightforward in my head and progressing well. Pictures to follow upon completion.

Next project is leaving my REAR friction drive kit in place. New engine motor mounting holes are drilled on the other side of the drive housing. That way, the engine and drive will spin counterclockwise and turn the rear wheel. The BMP clutch drum, axles and bearings remain in place. Friction roller is removed and substituted with the GEBE drive pulley. GEBE drive ring mounts normally. Since the engine and drive pulley is closer than the standard GEBE position, a shorter belt is installed. Belt is tensioned by adjusting the friction housing's modified rear supports, like two of these:

http://www.staton-inc.com/Details.asp?ProductID=2675

My project SHOULD work; expenses would be about about $125. The drive can be changed back to friction drive at no added expense.

After the drive pulley is perfectly aligned with the drive ring, either setscrews or welding can secure its permanent position.

My questions for now is...

Does anyone know the INSIDE diameter and OUTSIDE diameter of the GEBE drive pulley? Does it use a keyway? Sorry, I've never seen a GEBE kit.

If the pulley's 1/2" ID, then it'll slip right onto the BMP shaft. If it's keyed, I can either machine the BMP for keyway or tackweld the gear onto the shaft.

Please feel free to comment, either negatively

or positively.

I've been informed that the GEBE drive pulley's ID is 5/16" fine thread. :detective:

That won't slip onto my 1/2" diameter jackshaft. Unsure if this pulley can be drilled 1/2", then welded onto the shaft.

Does anyone know what the OD of any or every GEBE pulley is? I need to know the diameter where the belt rides, and the diameter of the outer lip.

Maybe I'll be needing to search for a pulley and belt elsewhere, which would work well with the GEBE ring's belt grooves. :detective:

TIA.

Smallwheels, I'll be waiting to hear your GEBE story.

Summer's here, so I'll have extra time for my bicycle projects until night school starts in August.

I've purchased the GEBE drive ring, so that's a start. I already have the BMP driveline and have found two online stores with $10 HTD pulleys and $11 belts. Just need to find the right pulley with 1/2" bore diameter. If I'm lucky and the OD is less than 1.375", I'll be able to remove the assembled driveline from the friction housing in one piece.

So far, this prototype should cost less than $100, which is a pleasant surprise. It can also revert back to friction drive at no extra cost.

That's freaking awesome!

Thanks for your feedback, Ron! I see you were trying to use the pocketbike's outer housing to mount the stock GEBE drive pulley. Most of what I'm trying to use is on the BMP friction drive kit:

BICYCLE ENGINE PARTS, MOTORIZED BICYCLE PARTS

I'm using everything in the BMP kit except the friction roller. An HTD drive pulley similar to GEBE's pulley will replace the friction roller on the shaft. If I find a pulley with a 1/2" bore diameter, then absolutely no machine work is necessary.

I have a used Staton wheel with 12g spokes that should work well with this project.

I'll be using a 2.2hp Mitsubishi on this prototype. Care will be taken to pedal from a standstill before applying the throttle.

Waiting for the GEBE drive ring to arrive. Still searching for the correct-size HTD drive pulley.

Good morning, Ron. Thanks for sharing the drive pulley's specs. I'm still searching for the right pulley to slip onto my 1/2" keyed shaft(which hasn't arrived yet). I know there HAS to be a $12 one that'll work for me.

The GEBE drive ring is meant to be used with 12-14g spokes. It should slip right on.

Good score on the electric bike, Ron. No probs at all showing it here.

It'll be an interesting build for all, if you install gas engine to run with electric motor!

I have one of those clutches laying around that I could scrounge from.

For belt tensioning, I'll be adjusting my rear support rods to stretch the belt. Adjustment will be locked in solid, because I'm using 18" of 3/8" allthread as the support struts. This SHOULD work; if not, a simple tensioner can be bolted on, near the drive pulley.

Yes, I'm in Hawaii. Days are longer, night classes are out for the summer. This'll give me more time after work for my bike project.

To solve the major problem of replacing the belt, a spare belt will be secured around the axleshaft, ensuring that no pulleys or collars rub against it. If/when the main belt breaks, the spare is easily dropped into place and adjusted for tension.

I inquired with an online company who can fabricate custom pulleys. I might order a twin pulley which is siamesed together, using a 14-tooth and 15-tooth. To change pulley size, simply loosen the drive pulley, align the new pulley size to the belt and tighten everything up.

Voila! New gearing ratio in minutes!