Friday, August 13, 2010

Beginning a Carbon Frame

Here are some pix of the preliminary steps of building a carbon frame.  As with other materials, we need to gather up our tubes, inspect them, and then prepare them to be cut, mitered, and fit together.

Here's  a pic of the tubes we'll be using.  Bike Cad has printed off the miter templates, which I have taped to the tubes as a guide for cutting and fitting them together.  Note that the outer tubes (which have no woven outer layer) are for the BB and Head-Tube.  As a consequence, we will only use a short piece of each.

NickFrame 003

As you can see, the three main tubes weight 535grams.  This isn't outstandingly light for three reasons: 1) These are untrimmed, the final weight will be less; 2) They have a cosmetic outer weave, which adds weight; 3) I'm building for ride and durability, not lowest possible weight.

Main Frame Tubes

Here are the Easton rear stays.  Note the molded in cable stop on the drive-side Chain-Stay.


Looking more closely, these only contribute 290 grams including dropouts (but without the derailer hanger or the screws which hold them together).

Easton Rear Triangle

Here is the Paragon Machine Works Ti BB insert. It's made to be bonded into a carbon tube. The knurling on the outside helps to give it a better bond and resist torque forces from the crank.

PMW Standard BB

And here is one of the two PMW Ti Head-Tube Rings. These allow the head-tube to be milled for a normal (in this case threadless) 1-1/8" headset. Let's say something like a Cane Creek 110.

PBW Headtube Inserts

Ok, we're up to 910 grams so far. Adding joints (glue, epoxy & CF), cable guides, the derailer hanger, water bottle mounts, and screws to hold the stays together, while subtracting for what will be trimmed off the tubes, and I'd say (just top of head) that a 1250 gram frame is likely. We'll see when we're done. But, while that is almost twice what the lightest frames run, it is still plenty light to create a bike that undercuts the UCI weight limits. More importantly, that weight will contribute to its longevity.

Now, just for grins, let me show you a PMW Aluminum BB30 sleeve. I won't use it on this frame, but it does help reduce weight. You can see that it has a spiral cut into the outer surface, rather than the knurling. One nice thing about working with CF, we won't heat distort this sleeve - which leads to post weld machining of BB30s.


Final note, I'll be off the grid (so to speak) for about a week.  Therefore, if you don't hear anything more for a while, its not because I've lost interest in this project.

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