Ahhh, it's the cold wet months when commuting seems to take a much heavier toll on my bike and I spend a portion of every weekend outside looking at it, scratching my head and then learning some new piece of maintenance devilry. I get better at it but round every corner there seems some new thing to learn and new tool to buy!
Yesterday I wanted to get to grips with the cranks slipping when I was in my highest gear and trying to put power through them. An occasional, but persistent slippage like when you change gear, I'd noticed this occuring on my last two commutes. I also wanted to adjust my brakes as they were getting very soggy. So up on the stand it goes and presto, the chain stretch tool instantly tells me the chain is too stretched. I'm excited as I hoped this was the solution, I'm also smug that I felt I knew what the issue was, had the tool to measure it and even had a spare chain sitting in a draw ready for just such an eventuality.
Fast forward a couple of hours and I've cleaned the casette and big cog, replaced the chain, spent a lifetime furtling my s*dding, bl**dy cantilever brakes ("all this is controlled by just this one nut", the park tools video states, "and this can be frustrating") and put everything back together. I jump on and arghhh the slipping seems to have got worse, rather than intermittent it is now pretty much constant. Still present only when in highest gears though and when putting power through the system. I can't replicate it when the bike is on the stand.
So what is it? I suspect that it's a worn casette. I've replaced my chain but not my casette, and an inspection of the casette reveals lots of the teeth are worn and slightly deformed. Hard to tell exactly as I think all the teeth are very specifically designed to be different shapes.
I've just order a new casette, a chain whip and a casette removal tool to add to my ever growing collection of bike hardware
Any wisdom UKC? Do I need to replace my chainring if I replace my casette?
Thanks for reading, was good to get that out of my system : )