2008-09-16

Bicycle Number Six: Procurement Update

I spent a couple of hours on the telephone and Internet today rectifying some of the issues in the parts I have available to build #6, my hybrid cyclocross/touring bike project.

The issue that's been killing me for a while with this bike is the incompatibility of the chain stays. After speaking with Hank at Henry James, I found that the 12 degree bend oval chainstays I have do not have the correct dimension for the bottom bracket shell I have. The solution here was to order a fresh set of straight oval chainstays.

This brings a caveat: I will have to increase the wheelbase of the bike in order to comfortably clear a 700x32c tire, the construction requirement. I'll see if comfortably clearing a 700x35c is a realistic possibility when I re-draw the bike in a CAD program. I'm okay with long chainstays, but not so long that it will make the bike sluggish to handle.

With the correct chainstays, and the silver brazing flux I ordered, all I need to build the frame is a jig and a torch! Instructibles has some directions for a rudimentary jig, which merely holds one tube at a time in plane. My goal here is to build the frame in as sustainable a fashion as possible, which in this context, means using infrastructure that I can easily and conveniently use for future frames, whether or not I stay here in Cambridge.

The fork is the other challenge of building this frame. I want to build my own, but I don't have the facilities to bend my own fork, nor do I foresee having time to build the correct fork bending apparatus in the near future. Nova Cycles offers a fully sloping cyclocross fork crown, which incorporates a 7 degree bend at the crown, while also providing the required strength and width for a good cyclocross fork. The bike will look a little funny, with these fork blades poking out at an odd angle from the head tube, but I have a greater chance of making a functional fork this way. I decided a while back that the fork would be threaded, and I'm going to stick to that conviction.

The parts should be in by the weekend. Maybe I'll make some progress this weekend. Before anything, I need to re-draw the frame in a CAD program, and determine the lengths of the stays (precisely) and the fork blades (estimate). Being able to braze the main triangle together, and cutting and mitering the stays to their final lengths and shapes, would be a huge win.

I'm still debating what color to paint the bike. The current winner is dark blue.