Effective January 1, 2023, junior gearing is NO LONGER restricted for all cycling disciplines except track. This is based upon ruling changes enacted by UCI as mentioned HERE
And by USA Cycling as mentioned HERE
Be aware that although UCI has enacted these rule changes, it is up to each individual national governing body / federation to determine the rules for their country. Since many American junior cyclists travel to Europe, you should be aware that the Cycling Federations of both Belgium and the Netherlands have decided to go counter to UCI rules and keep their junior gear restrictions in effect.
This will mean that if you travel to Belgium or Holland to race, juniors age 17-18 will still need to meet the rollout requirement (26′ in tallest gear with one crank revolution). That is usually obtained with a 52t chainring paired with a cassette with a 14 tooth small cog. Gear blocking is usually not allowed, but you should check with the Cycling Federation of the country you are racing in to confirm rules BEFORE travelling.
So keep your old junior cassette, just in case! If converting to a new 12 speed drivetrain, you’ll have to come up with other options to meet the 26′ rollout requirement. Also be aware that juniors age 15 & 16 racing in Belgium are subject to even more restrictive gearing, requiring a 52t chainring paired with a 16 tooth cog on the cassette (24′ rollout).
Both Belgium and Netherlands say they are reviewing their policies and may revise their rules, with an announcement expected by the end of 2023.
If traveling to Ireland to race (Junior Tour of Ireland in July), you’ll be pleased to learn that Cycling Ireland has ruled to scrap their junior gear restrictions per UCI guidelines. The SCNCA is not aware of the rulings of other countries at this time. If we find a list, we’ll post it here.