Comments on: A couple good links

By: David Bernstein

David Bernstein — Mon, 27 Nov 2006 19:40:00 +0000

Thanks for mentioning The Spokesmen. We love doing the show and it means a great deal to us when we hear from satisfied listeners!

--- David from The FredCast and The Spokesmen

By: Anonymous

Anonymous — Mon, 27 Nov 2006 04:44:00 +0000

Rivnuts, in aerospace they are a non starter unless isolated from the composite, crushing the fibres, breaks up the resin and bye bye strength as the fibres can slide and drift.

I think by and large the bike industry gets off easy.

I crack up when some owner writes to Leonard Zinn complaining about the galvanic problems on his "plastic" bike.

Unfortunately the UCI plays a role in frame shape, so some of the design problems are created from addressing those "rules"

By: michael

michael — Fri, 24 Nov 2006 19:02:00 +0000

Having worked on a few composite projects myself I have some insight into the issues raised. There are two distinct ways to construct a composite frame, monocoque (a somewhat inaccurate term) or tube-to-tube. Both have their pros & cons but in either case it’s important to view the material as a surface matrix and not as a volume of material. One of the problems with monocoque construction is getting the internal bladder (the thing that squishes the composite to the mold walls) to form tightly to the turns and radia inside the frame tubes so often ‘fillers’ are used to ease the transtion from one tube to another. Although it looks pretty shitty when you cut a frame in half it neither adds or detracts from the overall strength of the frame. This is determined more by how the composite fabric is ‘layed up’ and compressed/cured during fabrication. It will however add weight. Although I started out design ‘monocoque’ frames I now think that tube-to-tube offers a lighter and in many cases more cost effective way to manufacture composite frames. I am more concerned with the way we attach bottle boss’ using a pop-rivet deal which invariably splinters the composite fibers and looks ug-er-ly!

By: Tim Jackson- Masi Guy

Tim Jackson- Masi Guy — Wed, 22 Nov 2006 16:39:00 +0000

James- thanks for the mention and link love for the Spokesmen. It's a pretty cool group. (Even if I don't ever shut up.)

Anon- I hate the cosmetic outer weave too. It adds weight and doesn't do anything "real" for the bike. The protection is minimal at best and the look is just "played out". Everything from golf clubs, to fishing rods, to car hoods... it's everywhere. The look of the actual composite material is much more techie and intersting to me- which is why we have gone that route on the newest models. Since the outer cosmetic weave is just there for a uniform appearance, it really doesn't do much of anything for the ride and adds weight. I believe you'll see more bikes moving away from it. Besides, the high global demand for carbon fiber is driving the cost of cosmetic weave through the roof and limiting availability.

Hope you enjoyed the podcast. Next one should be around 11/27.

By: Anonymous

Anonymous — Wed, 22 Nov 2006 03:01:00 +0000

You finally got me to listen to the spokesman, that and the wife and kids are late getting home.

Regarding Carbon, (composite) frames, too bad the marketing guys demand that visually acceptable weave on the outside, not much strength added there most of it is going the wrong direction. I’m more concerned as to how the bond to the alloy parts is done, and the resin to “cloth” ratio. Oh yeah, they would all be better off with a suitable coat of paint to protect the material. All old news to the sailboat industry… Rant over.