I rode another rim into the ground yesterday. It's become a familiar scenario. I notice that the bike feels wobbly, I glance down and see that the rear rim has developed a waggle. Close inspection reveals cracks in the rim.
On the way to that final shimmy into the junkyard (or recycling bin), the wheels run round and true with little or no intervention after I build them. But the cracking bothers me.
I'm not one of those who believes in ultra-high tension. It needs to be high enough to hold the structural integrity of the wheel, not ratcheted several notches above that to ultimate rigidity.
Any time equipment fails I want to know why. Do I have to accept a steady rate of rim loss, given the roads I ride and the way I ride them? That wheel definitely saw hard miles on rough terrain. It held about 60 pounds of groceries in the panniers one day, and 30 or so on numerous other occasions before I got the BOB. But it might have had as little as 10,000 miles on it. I start to dredge my memory, reviewing the career of every wheel I ever built for myself. How did they do, under what circumstances?
It's harder with multiple bikes. Stuff gets put in service at different times. Use hours don't get logged. Looking back I have to estimate how much of each season's mileage goes to each bike.
Racing I expected to burn through equipment. And since I wasn't much of a racer, I didn't really burn through gear that much even then. Crashes took the most toll, if you don't count trashed sewup tires. I rebuilt the race wheels I bought used when those rims cracked, but I inherited all the fatigue they brought with them from the previous owner. He had been a very aggressive rider.
My longest-running rims are Weinmann concaves. I still have a set built in the early 1980s, which have been on and off bikes and now reside in the spare wheel pile because I don't run 27-inch tires anymore. Another set sees regular hard use on the fixed gear. Maybe it's time to revive that rugged design. It's definitely stronger than any box-section rim. I should have stocked up on all the available sizes. Early in the mountain bike boom, there was even a 26-inch model. They're heavy, but they go and go.
Speaking of go, it's time to head off for work. I need to order a rim.