British Cycling Youth Gear Restrictions – a guide to Rollback Limits & Locking Off Gears…the road season is back on, so if you are new to British Cycling road racing or moving up an age category, take a look at our reference guide. (British Triathlon are also continuing to roll-out gear restrictions to more and more events, it looks like this will become common place on kids triathlons in the near-future!)
Unlike other forms of Cycle Racing which have no restrictions, Road Racing to British Cycling Regulations has limits based on Age Group category. These are important for a couple of reasons, firstly to protect the children from overloading their muscles during a race (pushing too large a gear) and secondly to maintain a level playing field between competitors.
Each age group has a gear restriction in the form of a ‘Rollback’ distance (see table above). This is the distance covered for 1 full revolution of the crank, in the bikes highest (fastest) gear. It might sound complicated, but its actually very simple.
Common Component Combinations for BC Categories
There is a huge number of possible component variations to match gear limits, but here is a short list of the common, easily achieved set-ups using widely available parts – standard 11 or 12 up cassettes and common 110bcd chainrings. Yes, even more accuracy is available, but will often involve difficult to source, heavier components.
406mm wheels (28c tyres) use 38T chainring and 11t sprocket for U8’s/TriStart*
451mm wheels (28c tyres) use 38T chainring and 12t sprocket for U8’s/TriStart*
451mm wheels (21c tyres) use 38T chainring and 11t sprocket for U10’s/TriStar1*
507mm wheels (28c tyres) use 36T chainring and 13t sprocket for U8’s/TriStart*
520mm wheels (25c tyres) use 34T chainring and 12t sprocket for U8’s/TriStart*
520mm wheels (25c tyres) use 36T chainring and 12t sprocket for U10’s/TriStar1*
540mm wheels (25c tyres) use 40T chainring and 14t sprocket for U10’s/TriStar1*
559mm wheels (28c tyres) use 36T chainring and 13t sprocket for U10’s/TriStar1*
622mm wheels (20c tyres) use 36T chainring and 14t sprocket for U10’s/TriStar1*
622mm wheels (28c tyres) use 34T chainring and 12t sprocket for U12’s/TriStar2*
622mm wheels (28c tyres) use 39T chainring and 14t sprocket for U12’s/TriStar2*
622mm wheels (28c tyres) use 39T chainring and 13t sprocket for U14’s/TriStar2*
622mm wheels (25c tyres) use 39T chainring and 12t sprocket for U16’s/Youth*
622mm wheels (25c/28c tyres) use 52T chainring and 14t sprocket for U18’s/Junior*
*Component manufacturing tolerances can affect your actual rollout, especially tyres. Always physically check before heading off to a race! As you can see above, a fairly standard double chainset (using 52/39 chainrings) from U12’s upwards can be transferred from frame to frame, making life a lot easier. However, getting correct length cranks in standard double chainsets to satisfy the 10% rule is another matter!
This is how to check your bike…
- Place your bike in its highest gear (largest front Chainring, smallest rear Sprocket) with tyres at race pressure
- Lay a tape measure on the ground, position the bike with a crank arm vertically down, inline with the beginning of your tape measure)
- Roll the bike backwards (keeping it in a straight line) until the crank goes through 360 degrees (1 full rotation) and stop when it is vertically down again.
- As long as the distance covered is less than your age groups maximum ‘Rollback’ distance, the bike is legal. If its longer, repeat using the next Sprocket up.
- If you need to use a gear lower than its highest gear, you need to ‘lock off’ that gear so it can’t be used during the race – a simple task outlined below.
To lock any gears off and make your bike legal, simply follow these steps. Put the bike in its correct front Chainring and correct rear Sprocket to comply with the relevant Rollback…
- Using a screwdriver, turn the derailleur limit screw marked ‘H’ (for High), until you cannot change the gear any further down the Sprocket than is needed.
- Turning the screw marked ‘H’ clockwise (until it is not possible to select the smaller Sprocket) limits the overall travel of the rear mech in the high gears. Conversely, the screw marked ‘L’ (Low) can limit the overall travel in the lowest (largest) Sprockets, but you should not need to limit the lower gears.
The same procedure can be used to lock-off the larger front chainring too – useful for the U12 example highlighted above, using a double chainset on 52/59 chainrings.
British Cycling Events
During all British Cycling events all riders bikes are checked by the Scrutineers prior to the race (after signing-on) to ensure they are within the age group’s Rollback limit. Never attempt to cheat this, Podium finishers (and others selected at random) are re-tested immediately after the race is finished.
Why are very few bikes sold, at or near the gear limits? There are several reasons why bikes are rarely manufactured to match the BC Gear Restrictions;
- Due to size differences of children, many bikes are suitable for kids in several different age group categories.
- Not all bikes are targeted solely at Road racing, but are also suitable for Cycle-cross, which is un-restricted and benefits from different gearing.
- Economies of scale in manufacturing means it can prove expensive to specifically target one BC age group gearing, making the bike less appealing.
Because of this, its not uncommon to upgrade/modify gearing to get closer to the age groups limit, especially in the more competitive U12/14/16 and Juniors.
Finally, bear in mind the individual components that affect Rollback. Alongside front Chainring size (No of teeth) and the rear cassette Sprocket sizes (No of teeth) the overall diameter of the tyre and pressure are also critical. Not all 23c tyres are the same profile, so this can affect Rollback! Because of this, whilst you can manually calculate your Rollback mathematically (Front Teeth/Rear Teeth x Tyre Dia x π) there is no substitute for physically checking it before you race.
British Triathlon Gear Restrictions for Elite Tristar and Youth Draft-Legal Events
After a successful trial in 2015, British Triathlon amended the 2016 Rulebook for certain Elite level, draft-legal Youth Triathlons – imposing gear restrictions for the different age groups (matching the British Cycling Rollback limits, for the corresponding age groups). For 2017, the scope has increased again to cover all tarmac events for TriStar 2 and upwards age groups on SWS events.
Its only a matter of time before all events are gear-restricted. We think this is good news, as the same benefits will apply to young Triathletes, as they do to young Cyclists. We also hope they expand this to all age groups in the near future.