Hi, I recently bought my 10yo daughter a 24″ bike with a 2×9 drivetrain. It currently has a 11-34T cassette and 36/24T up front. She’s coming off a 20″ bike which had 3 internal gears and I’d like to convert to a 1X drivetrain both to simplify shifting for her and to reduce the bike weight.
I’d prefer not to upgrade to a 10 or 11 speed drivetrain for cost reasons and am wondering if going 1×9 with a 28T chainring will give her adequate gear range?
My bike came 3×9 with a 30t center ring, I never used anything else so took off the front shifter.. since I have switched to a 32t front ring with a 12-36 cassette.
I checked a gear calculator and with a 28t it would be approximately like losing the highest gear from the high range and lowest gear from the low range., so should be fine. If you find she never uses the low gears but wants to go faster you may need to go 30t, if you find she never uses the high gear but needs a lower gear, you can replace the 11-34 with a 12-36 cassette, or even a 12-40 (but they are hard to find and expensive)