Bicycle Materials
Bicycle Materials
(OP)
Hello guys,
I am new to materials engineering and am looking at making a BMX trick bike which is lighter than a steel one and just as strong. Please recommend me materials.
I have been looking at CNT-PPX, and something like polypropelyne.
What would be lighter and as strong or stronger than steel?
I have been mainly looking at carbon nanotubes with PPX.
Preferably just a light plastic like PPX or ABS.
Please help me so I can revolutionize the BMX industry with light bikes.
Thanks
I am new to materials engineering and am looking at making a BMX trick bike which is lighter than a steel one and just as strong. Please recommend me materials.
I have been looking at CNT-PPX, and something like polypropelyne.
What would be lighter and as strong or stronger than steel?
I have been mainly looking at carbon nanotubes with PPX.
Preferably just a light plastic like PPX or ABS.
Please help me so I can revolutionize the BMX industry with light bikes.
Thanks





RE: Bicycle Materials
RE: Bicycle Materials
He won some kind of competition, in which his prize was a very, very, expensive bike, made of magnesium, which made it very light.
He hated it, and stopped riding it almost immediately, because it was too flexible.
It was probably a lot stiffer than The Original Plastic Bike, which would have used vast quantities of Lexan, if it had been rideable. The Generous Eclectic company, then a big supplier of Lexan resin, basically swindled some people into tooling up a bicycle made almost entirely of Lexan and/or Lexan foam, which was a bit lighter than a common steel bike of the same era. Unfortunately, they made the frame geometry pretty much a copy of a generic steel bike, subbing foam for tubing, but using the same diameter, which made the bike very flexible. ... i.e., ignoring the advice in the GE plastic design manuals, to adjust geometries in proportion to the difference in elastic moduli.
At least the Itera Plastic Bike made some geometric accommodation for plastic's, er, weaker properties, but the designers didn't go far enough, and it was still too flexible.
I suggest you get started real soon, laying up carbon fiber prepreg on carved styrofoam disposable cores, and try to evolve as quickly as possible toward a bike that is about the weight you want, but first, even just barely stiff enough to ride.
Mike Halloran
Pembroke Pines, FL, USA
RE: Bicycle Materials
P.S. probably avoid ABS or Nylon as a matrix; rather weak, very flexible and made worse by high ambient temp. A more expensive engineering thermoplastic is probably worth it. (Nylon might just be possible, but bad in the wet.)
I like Mike's advice. You could gain valuable experience by starting out with woven carbon prepreg or dry carbon fabric wet layup before changing the design to suit a more cost-effective method of manufacture.
RE: Bicycle Materials
Switching to prepreg tape moved the mess to someone else's shop and kept our floor clean. The only capital cost was a big refrigerator in which to store the prepreg.
It was like night and day.
If the carbon prepreg gives you sticker shock, start with glass prepreg and use that while you're working out your process and learning how to bond the metal inserts you'll need for the steering head, the crank axle, and the rear wheel chain adjuster whatchamacallits.
Mike Halloran
Pembroke Pines, FL, USA
RE: Bicycle Materials
Chris DeArmitt PhD FRSC
President
Plastic materials consultant to the Fortune 100
www.phantomplastics.com
RE: Bicycle Materials
RE: Bicycle Materials