One of the requirements of the MS 150 is that bikes be inspected at an MS 150-approved bike shop. Luckily for me, the shop where I bought my bike and have it serviced is one of those. I called, and asked to make an appointment to bring the bike in. They said I wouldn’t need an appointment for that, so I put the bike in the car, and drove over.
I was waited on by the only mechanic in there who didn’t have arms, neck, and other places decorated with tattoos. (I’ve come to believe that tattoos are part of a bike mechanic’s uniform.) He put it on the stand, and started going through the inspection, spinning the pedals, shifting through the gears. Then he picked up one of those gizmos you use to measure chains.
“Uh oh,” he said. “This chain is worn. In fact, I’d call it ‘beyond worn.'” Was it shifting OK? Yes, I told him. “Ugh. That’s bad,” he grunted. Huh? “It means the cassette has worn along with the chain,” he said.
How many miles are on the bike? About 3,000, I said. “You really need to replace the chain every 1200-1500 miles,” he said.*
He went into a back room, and came out with a new chain. “This is a Shimano 105 chain for nine speeds,” he said, “so it’ll match your drive train.” He put on the new chain, adjusted the cable tension, and told me to do a parking lot test with it. “Really mash down on the pedals when you shift gears,” he said. “But be careful. The chain might pop off.”
I took it into the parking lot for a quick spin. The chain didn’t pop off, but shifting was clunky. Back in the shop, he made more adjustments. I took it to the lot for another spin. This time it was better, but still clunky.
“Yep, you need a new cassette,” he said. I was surprised to see that his computer search of their inventory turned up no 12-28 nine speed Shimano 105 cassettes. I thought it was a model in wide use. “The 10-speeds are taking over,” he said.
He found another, a SRAM, that he said would work fine, and put it on order. In the meantime, I can ride the bike, he said, but he again warned me about the possibility of throwing the chain.
When I first saw that the MS 150 required bike inspections (they put a little sticker on your stem to show that you’ve had it), I thought it was just another pain in the butt. After today’s experience, I’m glad I went. The new chain and cassette together, and the labor to install them, will come in well under $100, and I’ll have peace of mind that on a 180-mile bike ride, at least I won’t be worried about that.
*There is apparently much debate about that. The late Sheldon Brown’s thorough discussion of chain wear doesn’t mention how often it needs to be replaced.