Thursday, October 26, 2006


I finally broke down and bought BikeCad.

It's earned its keep already. I just did a new DCS frame design. The challenge here is to work within the available lug angles. This covers a pretty broad range of fits, but sometimes finding the right compromise takes a bit of trial and error.

BikeCad can display angles as different variables are fiddled allowing me to quickly zero in on the best lug set for properly fitting a given rider. Cool.

That said, I think a better answer is to develop a system where any angles are feasible at any joint. The theory of how to do this is relatively simple, and involves composite construction techniques that I've used in other contexts. But, the real key is making sure that the joint is stronger than the tubes. After all, no rider wants to find him/herself suddenly riding a pair of unicycles, eh?

From my perspective, the most feasible method is to miter tubes closely, and bond them with epoxy. Then layer additional carbon fiber on layers using a vacuum system with bleeder felt to extract excess epoxy and air.

So, there's a need to test this process to ensure that I get: 1) enough strength; 2) consistent results. Which means that I need some practice tube.

"Fortunately" if you look at Linda's blog, you'll see I had a little problem with a front triangle. So... I'm going to cut out the tubes and make them my first sacrificial "test tubes." After that I'll get some tubes from McLean and try to build myself a frame. So, stay tuned on this front too.

In a different vein, I've found some sources for Metax stainless tubes fro the front triangle. So, some stainless projects are on about to come online very soon.

Expect to see activity starting to pick up again.



Martin Manning said...


What are the angle constraints with the carbon kit?

Rick Guggemos said...

In general, figure for plus/minus one degree at each joint. In practice, some lug tube combinations may have more play than that once the clear coat has been removed. However, leveraging the additional freedom comes at the cost of strange looking joints.