Thursday, September 16, 2010

Juli's Wheels -- Pieces Parts

The wheel building class at Broadway Bicycle School started this week! I drove into Cambridge in one of my folks' cars, because Allyson was in town earlier this week, and she'd borrowed my Mazda for a few days. Borrowing seldom-used "spare" cars isn't always a good idea, and this week it turned into sort of a carnival of gremlins. I managed to avoid crashing into anything or being bitten. Long story.

Class was good. I'm one of three students, so it's a smaller and so far more social group than my last group. Each of us is building a different type of wheelset, with different hubs and different rim sizes, so it should be interesting to see how each project progress.

As I've mentioned before, my project will be to lace a set of 650B rims (either V-O or Velocity, depending on what's available) onto a vintage Specialized sealed bearing hubset. I think I properly spaced the rear hub for 126mm spacing (it was 120, originally), but we may need to adjust that in class. The 126 spacing will allow the rear to host a 7-speed freewheel, and then the final assemblies will see duty on Juli's new-to-her Schwinn frame (which is only a handful of parts away from being buildable).

This week, we mostly talked about what we wanted in the way of wheels, and why, and then chose parts. I already had my hubs, and knew what my rim choices would likely be, so most of the class I listened to and supported the dialog around the other students' wheels, which were being built from new and as-yet-unacquired parts. Did you know a Rohloff hub can run $1700, retail? That's a big nut, but then again, there's a little 14-speed transmission inside the thing, so it's a pretty sophisticated piece of equipment.

Apart from already knowing my rim and hub selections, I did have to make a couple of choices. I hadn't given any thought at all to spoke or nipple type. I think (can't remember for sure) I went with straight gauge DT Swiss spokes (vs. butted spokes), and I know I went with chrome plated brass nipples. The straight-gauge spokes are heavier, cheaper and not as strong as butted spokes, but these are wheels for a kid's bike, not a bike I'm going to put a thousand miles on per year.

To me, the way wheels lace up is really pretty cool. In a sense, spokes are long and skinny bolts, and nipples are nuts. The spoke winds through a hole in the hub, and then runs outward to the rim to accept the nipple. The nipple, in turn, fits through a hole in the rim and then threads onto the spoke end to hold it in place. Arrange a bunch of these around the circumference of a hub, running in a pattern to the rim, tighten them to uniform tension (either across all spokes or per-side, depending on the situation) and you have a wheel.

But there's a lot of detail in getting the wheel built right -- spoke length, choosing a lacing pattern, getting the path for each spoke right for the pattern, centering the rim properly (relative to the outer locknut surfaces on the axle), and getting everything tensioned properly and consistently. You should see the formula used to calculate the spoke length!

It should be a fun experience, and I'm looking forward to going back in two weeks to see what the Velo-Orange rims look like, and start learning how to lace the wheels up.

Then, once the wheels are built, I'll still need a few things to get the build rolling:

650B tires, and something on the narrower end to work with the chrome fork I bought for the frame
650B tubes to match the tires
Rim strips, and I'm going to try the new Made-in-America ones from Rivendell
The aforementioned freewheel
Brake and shifter cables, and housing in Juli's chosen shade of blue
A threadless handlebar stem, starnut and cap
Blue "cork" handlebar wrap
A kickstand

And probably a handful of other small parts, as well. Not a lot, though. The build should make for a good Christmas break project, I think, with a Thanksgiving tear-down of the Fuji.

I'll keep you posted.

All for now,


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