u/Barton06

Hey everyone, I’ve been trying to dial in the gearing on my 7 year olds bike, I started out with a 38/16 he was spinning out hard and loosing consistently. I changed out rims to sealed bearing bombshells and with that changed the rear gear to a 15. ( now at 38/15) He has been winning pretty consistently with this setup, but he is starting to spin out again. Would stepping up to a 40/15 be to big of a jump? What are some suggestions? His cranks are 140 it’s a red line jr frame. He is 49.75” tall, 21” inseam.