09.15.08
This is not about wheelbuilding
I’ve been building wheels. I tend to torque the hell out of my bikes. As much as I’ve tried, my friend Joel will tell you I cause him pain when I push a high gear hard, because riding behind he has to listen to the metal drivetrain complain. Wheels are delicately balanced things: a hub has 32 spokes to the wheel, 16 to each side, and if the tension is uneven from spoke to spoke, it’ll wobble from side to side, rubbing on the brake pads and wasting energy. If the tension is uneven from side, so that the hub is off-center within the rim itself, the wheel goes up and down as it turns, which causes all kinds of problems of its own.
When considerable force is applied unevenly, like through a pedal stroke, that force is applied more to certain spokes, turning the wheel, and over time, the tension of those spokes changes, sending it out of true.
A good wheel will remain true for years if you don’t run into anything. I not only don’t manage that, I run into things. A couple weeks ago, the person I was riding behind stopped unexpectedly, and I ran my spinning wheel into the back of his bike, driving my set of spinning-at-twenty-miles-an-hour spokes into his rear bracket, bending them badly. Which means my wheels need truing more often than they should.
Here’s the condensed version of almost every instruction manual on wheelbuilding:
-Get the right length of spokes
-Thread carefully in this pattern, or this other pattern
-Spin the wheel
-Adjust to fix the left-to-right wobble
-When that looks good, adjust to fix the up-and-down wobble
-Repeat those last two steps until the wheel is so nearly perfect that you strain your eyes to see the wobble
There are many problems with this. Wheels are shipped imperfect, however slightly. Picking the right length of spoke turns out to involve online calculators, or databases, and sometimes I stop and look at the wheel and wonder whether I just threaded in the right direction or not. The best way to replace a rim bent from hitting a pothole is to get exactly the same rim and then, spoke by spoke, swap the old rim out, maintaining the same lacing pattern and everything. That’s not really wheelbuilding though. It feels cheap, like I’m copying someone else’s work without learning anything. Fortunately, I’ve been building wheels with enough differences that there’s nothing to trace.
The worst thing for me is that I can come out of it with a perfectly well-adjusted wheel where the spokes are wildly unevenly tensed. One might be extremely tight, then a quite loose one, just barely past hand-tight, followed by another extremely tight. I’ll sigh, try to get a more uniform tension by doing a series of complicated small balancing adjustments, and it’s rare that that doesn’t create a different, equally obvious shortcoming somewhere else.
It’s extremely frustrating. I’ve been trying to build a new set for the last few weeks, following the collision. Sometimes I’ll watch a Mariners game with the truing stand on my desk and go through making large adjustments, twenty four spokes one full turn tighter each, and finally down to tiny, one-eighth turns.
A truly good wheel-builder can do a wheel with a speed that boggles my mind. They thread the wheel without looking at an example wheel or a chart on a monitor, but by putting the rim in their lap and quickly pushing thirty-two spokes in, lacing them correctly, and then they go through a series of quick adjustments on the truing stand, check whether the hub is off-center, which it isn’t, and set it aside to build the next one.
There’s a moment where the wheel comes together, where it snaps into place, becoming one thing instead of a rub connected to a rim by a network of metal rods. Even imperfect, it’s a wheel. Sometimes, in going through my endless truing, I would pick it out of the stand and see that it wasn’t working, and resign myself to restarting. Or I’d realize that without knowing it, my brainstorm to tighten all the crossing spokes half a turn had brought the whole thing together, and that I could ride it right that moment if I had to.
Tonight I finished the replacement front wheel for the one destroyed. I’ve been riding back and forth to work on a front wheel I took off my training Cannondale, built out parts so old they don’t show up in Google searches. The new wheels are beautiful, quite nice, costly, as good bike parts are. I may have built it with incorrectly sized spokes, which isn’t my fault because I bought it as a set. But it turns out that spoke length calculation isn’t quite an exact science, and there’s always the chance they thought I was going to do a different pattern.
It was ten, and I’d finished up my second restart build happily, using my own set of instructions, which essentially came down to:
-Thread spokes in a two-cross pattern
-Tighten the spokes enough that no spoke’s floppy
-Spin the wheel
-Adjust to fix the left-to-right wobble
-When that looks good, adjust to fix the up-and-down wobble
-Repeat those two steps
-Consider the wheel and how I feel about it
-Adjust the sections I don’t feel good about
I went through this while watching an interview and paying a lot more attention to the interview than my own inadequacies as a wheelbuilder. I spun it with the tolerance so tight that when the wheel rubbed left-to-right I couldn’t tell which side it was on without touching the calipers to feel the vibration when they touched the spinning rim.
I put it on the bike and in my bare feet rode it out on the street in front of my house in the full moon. New wheels sound notes that first time, stressed differently with an inflated tire around the circumference and a rider’s weight squishing them. They twang as they re-sort their positions at each junction in the lacing. It’s like metal strings being plucked, and it always makes me smile. As I pulled back in, walking the bike, I saw that the brake pads rubbed. The wheel would need a little more adjustment, so I pulled it off, deflated the tire, and headed back to the truing stand.
Tomorrow I’ll ride my new wheel to work, and I don’t know how it’ll go.
