If your youngster is racing in British Cycling (BC) road/track/roller racing competitions they are governed by BC rules – this includes gear restrictions.
To help make the gear restrictions easier to understand Simon wrote this:
A number of different largest chain ring/smallest sprocket combinations will achieve the maximum allowable gear in your age category – some get slightly nearer to the limit than others.
The favoured Youth A combination tends to be 52×16 but the cheapest is probably 39×12 as most bikes are fitted with this combination as standard. You can of course ‘lock off’ your gears so you can’t get into the smallest sprockets (maybe the 11) or maybe the big chain ring but this will restrict the number of gears at your disposal eg. it might turn a 20 speed bike into an 8 speed if you lock off one chain ring and the two smallest sprockets, it may also get you too far under the limit which will put you at a disadvantage e.g. 53×17 would put at about 6.56 metres but 53×16 would roll out at about 7.00m and this is slightly too big for a Youth A rider.
Of course things like tyre size will affect the roll out and some testing is more exacting that others, the best is done in a channel so the roll out is measured in a straight line rather than a wonky one.
Before a race the Commissaire will perform a roll out test with your bike in its highest gear, only if it passes this test will you be allowed to race. Don’t change your gears after testing as they will test a few riders again after the finish.
|BRITISH CYCLING GEAR LIMITS|
|CATEGORY GEAR LIMIT EXAMPLE FOR 700c WHEELS and a 23mm tyre.|
|Age category for the year.||Roll out metres||Approx Gear Inches||Chain ring/Sprocket combinations that work.|
|Youth E Under 8 at 1st Jan||5.10 metres||64 inch||39×16 / 41×17 / 43×18 / 48×19|
|Youth D Under 10 at 1st Jan||5.40 metres||68 inch||41×16 / 43×17 / 46×18 / 49×19|
|Youth C Under 12 at 1st Jan||6.05 metres||76 inch||39×14 / 42×15 / 45×16 / 48×17|
|Youth B Under 14 at 1st Jan||6.45 metres||80 inch||39×13 / 42×14 / 45×15 / 51×17|
|Youth A Under 16 at 1st Jan||6.93 metres||88 inch||39×12 / 42×13 / 47×15 / 52×16|
|Junior Under 18 at 1st Jan||7.93 metres||100 inch||52×14|