Originally Posted by
cyccommute
Let’s start with why you think the chainrings need replacing. Yours are relatively new. I’ve got chainrings with about 25,000 miles on them with loads more miles before they need replacement. Chain rings wear but they wear slowly.
If you are looking at your chainring and seeing teeth that don’t look like others, that is by design. Modern chainrings are asymmetric with different teeth profiles in different locations that aid in shifting. Often people see a flatter tooth and freak out. But that is a feature, not a flaw. A picture would be helpful in assessing whether they need replacement or not.
Your crank likely has a 110mm bolt circle diameter (BCD). Measuring it would be better than guessing but I can’t reach through the screen.
Here’s a link to what ring to use based on the measurement. There is a link in that article on how to measure the BCD.
It’s relatively simple to replace the chainring (if you
really need to replace it). Just unscrew the bolts and swap the ring. You may not even need to take the crankset off to do so. You can usually work the old ring off over the pedals or just remove the pedal before hand. If you are lucky, the chainring bolts will use 5mm Allen wrenches on the front and rear. If not you’ll need one of
these. The chainring nut wrench is in hot contention for being the worst bicycle tool ever!
Don’t worry too much about torque, just get them tight. You might also take this opportunity to replace the chainring bolts with ones that use 5mm Allen wrenches on both sides. There are lots of aftermarket chainring bolts out there. You can even have fun with colors if you like.
Thank you so much!! Excellent information. It does appear I should have taken some pictures which I will do and post back so everyone has some visual reference. Point taken about some teeth not looking like the others. The teeth on the big ring do look different than the other two and that was the basis for my conclusion, but again, pics will be added shortly. I do log between 5,000 and 6,000 miles a year on my bike, so likely at least 25,000 on the factory chainrings. I swap chains almost obsessively, as I learned fairly early on in my bike ownership that using chains for too many miles can cause premature wear on chainrings and cassette cogs. I install a new chain at the first sign of wear on my wear gauge.