new carbon fiber muni (teaser)

some of you may remember back a ways when I completed a carbon fiber muni I designed. Pretty much it was sort of lame but a good starting point. Despite some major design flaws it held up to some sizeable abuse before finally checking out. I finished the design for the next generation. It is lighter, stronger, and this time, all carbon fiber except for the seat tube and bearing retainers. It is kind of a pitty, the frame weighs 50 grams (0.11 pounds), now, and probably about 90 grams (0.2 pounds) after the next infusion, but the whole frame will probably be about a pound with all the hardware on it. One advantage to my new design is that the cut time is about 10% of what it was on the last one, meaning that I may be getting close to a possible production model. Also, I designed a new sort of bearing retainer. I think you all will like it. No pictures now, as I plan to first bust it out first for motorama. I’ll have some soon. But just curious, would many of you be interested in a carbon fiber muni? Sadly, I don’t think they would be cheap, as manual labor cost, and consumables on resin transfer moulding still kill, even in volume.

How does CF do in extreme cold, say 20 below?

Re: new carbon fiber muni (teaser)

Teaser! (ahh, we were warned). Ya, I’d like to see your bearing design and how it was integrated into the uprights. Most of my designs are still just that- designs -because my weight estimates come out to close to what can already be done in chrome alloy (1.4lbs+). I look forwarad to getting a finished weight of the frame and bearing holders without the post clamp, as well as performance/durrability with the lay-up used for that weight.

Of course, I’d like to see your molds more than the finished cycle. Did you invest in the equipement for gel-coating? Will you finish the part with a spray-on coat, or is it coming finished off the mold?


Have fun at motorama.


funny you mention the moulds. I will either show you a moulding technique that costs next to nothing and is very effective, or I will show you a way to get very poor volume fractions. After the next go round this evening I’ll know the answer. I’ll show you the bearing retainers soon, but I am still a little skeptical of the design as it stands. Sorry to up the ante on the tease fest. As for finishing, I don’t know much about how to finish composites, as my days are pretty much filled by making composites and breaking composites, and you don’t take your pet to get its haircut on the way to having it put to sleep. If you have some suggestions I’m definately open to them. As for how I got to the low weights, it is less a function of layup and more due to the wonderous company Diab.

U-turn; I can’t say for sure about the cold temperatures, but I have a friend who did some thermal cycling of composite materials a few years back. They were high temperature prepregs. He first decreased the temperature to about -20 degrees c, then raised it very fast to about 100 degrees c. He did this several times to his specimens and found no appreciable change to the fracture toughness. I’m guessing that you are wanting to know about sustained use at cold temperatures. I don’t know for sure, but it is my suspicion that like other materials it would be more brittle, but I don’t think the effect would be large.