Tipmart

The company in the UK that I bought my 9yr olds racing bike from sells multiple sizes of single chainrings for the kids bikes starting at 30T and going up 32T, 34T etc etc

https://kidsracing.co.uk/collections...12671464603711

My son competes in road races, normally 6-8 miles long and in triathlons, mostly 3-4 miles in length. Most of the races are on pretty flat courses with a few small hills. When he comes out with me on rides we will tackle bigger and longer hills

He has been riding on a 32T single chain ring and I'm wondering would there be any benefit or harm to moving up to a 34 or 36T ring

thanks

Doge

UCI removed junior gear restrictions. Countries should follow.

Choorliez

I have 2 arguments:
Firstly, moving from a 32T to a 34T or 36T chainring may increase the gear ratio and make pedaling harder for your son, especially on longer rides and bigger hills. It's important to ensure that your son has the necessary strength and stamina to handle the increased resistance without risking injury or fatigue.

Secondly, the type of races your son participates in and the terrain of the courses should also be taken into account. If most of the races are on flat courses with only a few small hills, a 32T chainring may be suitable for your son's needs. Changing to a larger chainring may not necessarily result in a significant performance improvement in these types of races((

Doge

See cadence. I see no harm in a bigger gear, but the kid needs to be on top of it and not bogged down. A smaller gear allows for some snap.
The kids have far less trouble than adults pushing a big gear. Kids jump of things several times their height. Adults do it less. I know of no evidence having looked for it for decades that bigger gears cause issues. Smaller gears can cause overuse tendonitis.
For a kid, spinning too much is worse than pushing harder.