Carbon Fiber anyone?



I was glad to see Vern's full suspension bike with the GEBE set up on it as that is what I am considering.

The question I have for this forum is has anyone put an engine on a Carbon fiber bike?

I have a Trek Y22 with full suspension that is about 12 years old that I have not ridden much at all. Broken bones from my younger years on M/C, skiing and mountain biking have taken there toll on the bod and so I am really excited about this setup.

Any opinions on whether a carbon fiber frame and full suspension would be safe? I know they are strong but I am wondering about vibration and longevity?
i can only speak of what i know about...with a rack-mount, you're open to more options as far as frame-style & -material, rear wheel integrity is all important, tho...with my GEBE tanaka, there is no vibration to speak of, and i wouldn't hesitate to install it on almost any bicycle :cool:
I'm new to this motorized bike idea, but I can tell you that carbon fiber is as fragile as it is strong. This stuff is very brittle and any where you mount something to it, you must be very carefull to find a way to spread the load/forces over a large area. You can't just drill a hole and put a bolt through like you can with steel.
Hope this helps.
Last edited by a moderator:
That is what I am worried about Douglas65. I have heard of rocks hitting this stuff and breaking the frame. I dont think they make the exact frame anymore so a replacement would probably be better (aluminum?) than original if I could get them to warranty it.

The one good thing is the rear forks/swingarm setup is aluminum so that makes me feel a bit better. I weigh about 175 pounds and with a 15-20 pound motor I dont think I would be overloading the bike.

I do need a full suspension as I have broken several bones in the past. Pelvis, back, ankle, shoulders etc. Makes me hurt just thinking about the dumb things I did as a kid!

Winter is coming so maybe I can get a fire sale on someones unloved full suspension bike made of a more durable material.
Motorized bicycle frame materials

Hello, I'm not a rack-mount guy, but let me offer what I've learned over the years about materials, and bicycles. Generally speaking each tube has no inherant strenght except for trying to crush it lenghtwise, that would be to put one end on something and try to push the tube straight in.

Bike frames are built (so often in triangles) to increase overall strenght, while staying lightweight. Here they are trying to make the most, from the thinnest and lightest, this is why you should never drill a frame, unless you will weld a tube to both sides of the hole you drill.

By their very nature, aluminum and brass are very prone to cracking, this has a lot to do with molecular structure and a phenonum called "grain".

I will never mount an engine (read vibrator) to a non-steel bicycle, as the bicycle, no matter how well engineered, was designed for a life of smooth rolling. I'm staying the course here with Carbon Fiber also. I was in a shop, and the guy said they do not even dare get oil on the fibre, and you'd consider gas, or two-stroke mix?

Point to consider, NO bicycle mfg, shop, distrubitor, owner, or even grandchild of owner is ever likely to do a warrantee on any part, once an engine has been introduced to the mix. If you have not experianced this, put an engine on an old road bike, and take it to a roadie shop and ask them to build you a new wheel (Duck quick here, as it will get wild)

Steel is your friend, forget about the few extra pounds, if you feel inclined, increase engine size to make up for the weight of your frame.

Staying alive riding steel!

I've never had anything to do with carbon fibre framing on bikes - but I think the thing that would worry me most about trying to use it wouldnt be so much the vibration factor as the brittleness of it.. if its bent or stressed it will so much more likely to just fracture than steel/alum/etc..

There are however a couple of things I have thought of that might help if you are planning to use the CF frame... one is packing the frame hollows with something such as expoxy - to make a lightweight but still more solid frame.. the other is using some method to insulate the vibration of the motor from the frame - which would be easier using the GEBE/rackmount method...

There is one other choice... and that is mounting the engine over the front fork AKA velosolex and the German Victoria FM38. Assuming that you fit a metal suspension fork there would be much less of a vibration problem because any vibration would be taken through the suspension on the fork itself (mounting to the damped, not undamped area of the fork) and therefore would not harm the bike...

Jemma xx
Step on a fishing rod in carbon fiber and you'll see what happens. Carbon fiber is extremely strong in bending, but not particularly strong at pressure with a clamp around. Making motor mounts in carbon fiber instead
you could buy a sheet of 1mm thick sheet metal, cut out two rectangular sections (the width being the same as the frame tube circumference), curve them to wrap around the frame tubes, and mount the engine onto them.