Monday, January 12, 2009

Next bike


Photo sniped from hubstripping


Remember all that talk about being satisfied with the bikes I have now? Well that was crap.

I've been sitting on this hub for about a year now. It's a Sachs Torpedo Duomatic: a 2-speed kickback coaster-brake hub. Liza had an American version (Bendix) of this hub on her Schwinn. This hub came off my old Raleigh 20 that ended up going to Tarik

Anyway, my plan is to build up a wheel around this hub and make the Shogun into a big-kid bike. What this means to me is just a simple bike with a coaster brake: no fenders, no rack. It will have platform pedals, 700c wheels with 32 mm Pasalas. I've got some Orgin-8 Space Bars (rip-offs of the One-one Mary bars). It'll be a fun bike for fast cruising, trail riding, and summer commutes.

There are a couple things slowing me down though. 

Thing 1: Frame Crushing

This hub as an OLD of 112. OLD is "over lock-nut distance," which corresponds to how wide the rear fork of your frame needs to be to accommodate the hub. 112mm is narrow by today's standards --  which are at the narrowest, 126 mm, but they're more commonly 130 or 135 mm. 

The Shogun has 130 mm rear dropouts. I plan on squeezing  and cold-setting the rear dropouts to 117 mm to deal with this hub. Actually, I plan on taking the frame to John at REI to have him do it. Last time I farted around with bending up a frame, I screwed it up. 

I think the tool to have for this operation is the Hozan frame tool. The Hozan tool encourages a more deliberate, iterative approach to spreading and compressing the fork ends.  I have the Park Frame and Fork Straightener, which is a much more brute-force lever deal that encourages me to over-do it and make huge corrections in a single operation. Yes, I'm blaming my ham-fisted, gorilla technique on tools. 

Squeezing the frame doesn't matter much to a steel frame if it's done right. It's the kind of thing though that slows me down because I feel like I should do it. I've got the Park tool, I've got the dropout alignment tools, and even a frame alignment gauge. I feel like a total wanker not doing this work when I have all these tools. But, as any wanker gear head will tell you, I don't have all the right tools. The Hozan tool would be nice to have here as would a work stand that attaches to the bottom bracket for ultimate stability. 

My way out of this is to tell myself that I'll continue to get better at the rear triangle thing by working on bikes at P2P. We see some bent up, mangled stuff there that are good practice frames to learn on. 

Thing #2: The Hub Overhaul

Before I build the wheel, I want to overhaul the hub. I've not taken apart a 2-speed kickback before. I've taken apart a few single-speed coaster brake hubs and I've had good success. To balance those successes, I have a half-disassembled Sturmey Archer 3 speed in my garage that will likely never be put back together. So, I've been putting the overhaul for a while.

Looking at the exploded diagram of the Sachs, I think I'll be alright. Last night, I found this guy's pictorial essay on reassembly, so I'm very confident now. I just need to set aside the chunk of time to do it. Perhaps this is how I'll spend my Friday night. Woo-hoo, who says I don't know how to par-tay?

2 comments:

rory said...

squeezing the dropouts together might affect your tire clearance.

since you're taking the hub apart anyway, you could just replace the axle with a wider one and add spacers to make it fit...

John Speare said...

Yeah. I've thought of that. It's really hard to tell from the exploded diagram, but I'm pretty sure the axle is proprietary, with a little lump/gear-chunker on it. That's how the old version was. If it's a standard axle, I'll do that for sure.