What I Don’t Know About Bicycles, No. 1

Okay, I’ve been wrenching on and off since around 1987. Sometimes, it’s been more serious wrenching than others, but hey, at least I’ve been paid to wrench a bit, I’ve done almost all of my own bike work, and I know at least something about bicycles. Or so I thought.

As you can see by the photos, I’ve recently completed a new build. It’s a painted Ti frame from GVH Bikes, with a new SRAM Force kit and a bunch of other goodies. Although I own mostly 1980’s vintage steel with nice, easy quill stems and alloy bits, I own a torque wrench and I can read, so what the hell. I might as well have a modern racing bike, right? Some non-ferrous metals, some carbony goodness, that sort of thing.

In a couple of nights, the bike’s built. Then, the “so easy” build starts demonstrating what I apparently don’t know about bicycles.

The first thing I don’t know about bicycles: some torque wrenches can’t be trusted.
My first ride starts Sunday. I figure a quick 35 or so near my house will give me a chance to work out the quirks with the bike and still be close enough to home to fix things if need be. Within 2 miles, I realize my seatpost is slipping. Now, I’m not too concerned, since I have a wrench of just the right size to fix this. I pull over, hop off and readjust the seatpost, uncovering a nasty bit of decal damage to my pristine new Ritchey WCS Carbon seatpost. Joy. Whoever it was who decided that the decals on this seatpost should overlap the seat tube contact area should be beaten by a mob of coffee-shop cyclists in full Discovery kit.

Great. The seatpost is now scratched nice and pretty, so I can at least ride the bike. It is meant to be a rider, after all, and these sorts of things happen.

A mile down the road, and I still feel like it’s slipping. Of course, I’m paranoid by now, so I watch it. And watch it. Dammit, I knowit’s slipping. Wasn’t the seat collar at the edge of the “R” in “carbon”? Now it’s on the “R” proper. So, I slow to dismount and unclip my left foot, which swings wildly out, with an attached crankarm. More joy. I thought I tightened the thing, but as it’s clipped to my foot, I guess I didn’t tighten it enough. I make it to the edge of the road, and of course, I don’t have a wrench to tighten the crank arm with me. The first couple of threads have stripped a bit, and there’s a bit of aluminum wire from them floating about. Most of the threads are completely intact.

The seatpost has definitely moved a little bit. People have complained quite a bit about carbon/alloy or carbon/steel junctions, and my own little kludge–a Cane Creek seatpost shim for 27.2 to 30.0 mated to a Ritchey WCS Carbon seatpost–is setup just right to have some problems. That, however, can be rectified with the addition of the right materials, namely some of Tom Ritchey’s own Liquid Torque.

I decide to bail on the ride and call for backup, which arrives shortly in a Toyota Sienna minivan.

One day later, I figure I’ll repair my mess, mount the lights and go for a night ride in a nearby neighborhood. I dial my torque wrench up for the crankarm and tighten it until the wrench clicks. Done. No problem. I don’t think this will present any more problems, but I’ll get another crankarm ordered just in case. I reset the wrench for the seat collar, reset the seatpost, and start tightening. Crunch. The seat collar snaps in two and I drop the torque wrench, which neatly bounces across the seatstay, taking a nice 2mm chip of paint with it. Okay, now I’m angry. I drop everything and stomp off to eat a large bowl of cereal and three slices of pizza. Screw weight loss. Screw riding. Why don’t I just sell these things or just throw them out?

An hour later, regaining my senses, I question my torque wrench. I know I tightened that crank. I also know I used the wrench on the seatpost. Apparently, something weird is afoot. I’ve had the wrench for some time, and I’ve never had it do things like this before. Hmmmmm….now that the doubt is in my mind, it’s there for good. This thing is going out.

Looks like I’m going to by an Effetto Mariposa torque wrench. At least with it, I’ll know it’s all my fault.

2 thoughts on “What I Don’t Know About Bicycles, No. 1

  1. Torque can be evil. I have a Tarmac E5 and have been petrified that I will do something horrible to the stem ($), seatpost ($$) or handlebars ($$$) when I tighten them after taking apart the bike to travel. No one has ever mistaken me for a mechanic. So I bought a Park Tools beam-type torque wrench, which is supposed to be pretty accurate and simple. I discovered that the numbers Specialized gives for tightening the parts are ridiculously low so rather than have an accident when the stem falls off, I just tighten everything with the trusty Y-wrench and pray pray pray. Nice blog!

  2. I agree, there’s little point in following the torque suggestions for some parts, given the variability of the connection you’re making. “Just enough to keep it secure” sometimes falls outside the range of the tension guidelines. It obviously allows the manufacturers to avoid some liability with parts that are lightly constructed, and I’d imagine there’s quite a bit of room for error in those suggestions.

    Unfortunately, my “twist and pray” strategy hasn’t always worked. I’ve torn off a few keys in stuck locks and if given leverage, I can certainly break a seat binder bolt. Thus, my reliance on the torque wrench. Just last night, I switched to a Craftsman 3/8″ beam-type torque wrench from Sears. If you examine it, it appears to be of similar manufacture as the beam-type offerings from Park Tools. You just have to do your own conversion from foot-pounds to inch-pounds, or rely on Nm. It’s user-calibrated, too. I recently found out that “click-type” torque wrenches should really be calibrated professionally annually. Thus, this simple, home-use wrench is likely to do a better job. If not, there’s always the Effetto…

Leave a Reply