May 19, 2009

Big in Japan: Part 2

For those of you who missed the first part of the story, scroll down a bit and find the first part to get caught up.

I got the chainstays and dropouts on this frame today (and yes, that’s not much, but I also packed and shipped 3 frames, 4 forks, and a bunch of weld rod, so I only was able to work on the frame for an hour or so).

For a 300 pound rider, I wanted appropriately beefy chainstays. For most bikes, I’d use tandem stays (which I have a pile of, beacause True Temper discontinued them and sold them to me for like 75 cents – if you read back a ways, so far the only thing I’ve made with them is a fork). But with those (straight) stays, I could probably only get 45c or so worth of tire clearance. Derek wants to use Big Apples (about 60mm width), so mountain bike stays are the way to go.

I finally decided on some Nova “Mad Max” chainstays. 1.5″x.75″ oval, 9mm, super burly. Also pretty shoddily made (one is 19mm width, one was 20mm). A little asymmetry won’t kill anyone, though (and in fact you can’t really even see it).

The chainstays are so huge (along with the huge seat tube) that they have to be compound mitered (by hand) to the seat tube, as well as the BB shell. Here’s a shot of about halfway through the process…

He also wants a chainstay mounted disc brake, so I ordered some fancy schmancy Paragon low disc mount dropouts. Pretty spiffy!

Before anyone asks: Using these is about 30-40g heavier than breezers with a separate disc mount (that’s taking into account the *much* shorter chainstays needed with these suckers, as well as the disc mount and brace needed with a conventional setup). Really not much of a weight penalty at all. I anticipate doing a decent number of bikes with these – I really like them and they save some work on my part (no need to miter or weld on a disc tab or seatstay/chainstay brace).

I’m guessing that there will be problems making the caliper fit in there on some smaller frames (and I’ll do some experimenting to see). Worst case scenario, I’d have to put a second bend in the seatstay to arch it up over the disc caliper. For those who are curious, no, there won’t be any upcharge for these.

Only quibble: I wish they were post-mount.

So there you have it. Tomorrow I should be able to finish up the rear end and I’ll do a third post to talk a bit about the seatstays and such.