It's so obvious, but this past weekend, I appreciated the point yet again: the better part of technical skill is the ability to diagnose. And the ability to diagnose is hard to acquire in any way other than by experience.
If you ever listen to Car Talk, you'll hear Click and Clack produce a hilarious repertoire of noises as they try to help their clients close in on the causes of their cars' ills. When our bikes go wrong, we often have to depend on our ears to help us figure out what's wrong.
Of course, this is almost common sense to us. If the noise is coming from directly below us and happens at every pedal stroke, it's probably something with the BB or crank or pedals. If it's coming from behind us or in front of us, and happens every wheel revolution, it's probably something with a rim or brake.
But then there are those more elusive problems. The pinging noise, that you just can't pin down. The noise that seems to come and go with no reference to pedal strokes or wheel revolutions. And of course, the noise that happens only when riding and under extreme load.
And so begins the sad tale of my week.
A couple weeks ago, I replaced my derailleur pulleys, which were worn down to little points. The pulleys I put in were after-market, and after installing them, they appeared a little wobbly on their bushings. Well, I thought, I'll try them and see.
Over the next few days, things were pretty much working OK, but I began to get some chain skips. Before diving into that problem, I checked the chain for wear, and found that it was way, way past replacement. So I put on a new chain and cassette.
When I pedaled under load, I began hearing a pretty loud and constant crumping sound from below me. That's right, "crumping." Like the sound of artillery in the distance. The volume varied by pedal stroke.
I checked that the cranks & BB were OK. No apparent problems there. Could it be the chain? The chain I had put on was labeled as 6/7/8 speed, whereas the chain I had taken off was 7/8. Indeed, the pins of the new chain were a hair longer than on the old chain. There seemed to be plenty of clearance for the chain; nevertheless I put a 7/8 chain on.
Maybe it was those damned pulleys after all (thought the sound was not coming from back there). I swapped in a different RD.
I was getting desperate. My Eggbeaters were pretty wobbly on the their spindles. So, I did the long-overdue overhaul on them.
There was only one thing left to try -- the chain rings. I swapped in a pair of new rings.
And that did it.
That the rings had worn to such an extent that they were virtually incompatible with a new chain says something about how worn I had let the old chain become. And the derailleur pulleys had probably been prematurely worn to points because of the worn chain.
I was not out of the woods yet, though. Now that the crumping sound was gone, I began to hear the pedal-cyclical snap, crackle, and pop that usually means an insufficiently torqued crank arm. So, I made sure the cranks were properly torqued.
I took the cranks off, cleaned & greased the interfaces with the BB spindle, and prepared to reinstall them. Now, before I pulled the cranks, the crank puller had a washer behind the pad. I'd always wondered why that was there. After I pulled the cranks, there were two washers. Aha! When pulling cranks, I had neglected to pry out the washer that sits between the crank arm bolt and the crank itself. When subjected to the pressure of the pad, these washers had slipped over it, and were pulled out when I unthreaded the puller from the crank arm. So I had been riding with one crank arm missing a washer, and I was about to start riding with both missing a washer. I swapped in a different pair of bolts, with integrated washers.
And that did it. Now the bike rides quietly, for the first time in a long, long time.
So, this post was nominally about the value of experience in tracking down problems through sound. But an even deeper theme is the problems that arise from deferred maintenance. I am bad at routine maintenance; I generally let things go til something breaks. I tell myself that I do this because it exposes me to a wider range of problems than I would otherwise see with a properly maintained bike. Well, maybe that's true. How many bike owners keep their bikes properly maintained, and bring them into a bike shop before something goes wrong. But a large part of the reason I let things go is, to be honest, laziness.
OK, that's the end of this sordid tale of sex, violence, and greed.