Filed In: Process
November 29, 2019 | Chris Blandford
Moving on to the chainstays.
Steps for today:
3. Tab Dropouts; Slot Chainstays
4. Braze Dropouts to Chainstays
5. Finish Chainstay Ends
Before I dive in, one thing to note. For the first couple frames I made I did things one step at a time, with a sort of process tunnel vision. Now, however, I tend to do things whenever it makes most sense in the overall build. An example of this is with the chainstays. Previously, I would’ve brazed the front triangle together before even touching a chainstay or dropout. Now, however, I work on these as separate sub-assemblies of a larger whole, prepping everything in anticipation of finally joining stuff together.
Anyway. I begin by laying my chainstays on top of my overview drawing. I include the tire, chainring(s), and crankarm in these drawings, and check that the chainstay will clear all three. I also check that the outer diameter of the dropout end isn’t wider than the tab on the dropout. It’s a bit of a balancing act to choose the most appropriate chainstay (to this point I’ve only bought pre-formed stays--I haven’t bent my own) and get it ideally positioned. Once satisfied, I trim the dropout end of the stay to length and rough-cut the BB ends to length. Then I lay the chainstays on my surface plate and run a straightedge across their tops, scribing a “top” line onto both.
Tool note: I use my Anvil fork jig as a makeshift chainstay jig. A while back, I made a crude little adapter that fits in the steerer tube holder of this jig. It holds the BB ends of the chainstays in place while I work on them, kinda like a crappy chainstay mitering fixture. (I miter out of the fixture, but the jig is helpful for getting everything in its place.) I use the fork rake measurement and a little math as a makeshift BB drop/rise indicator.
Next, I put a tab on the dropout. For chainstays, I’ve been making these 8-10mm deep. I check the internal diameter of the small end of the trimmed chainstay, and take off an equal amount of material from each side of the dropout (hacksaw first, then files), so that the tab fits into the stay.