Performing a Roll-out Check
For Youth category racing, there are restrictions on the maximum distance a bike can travel for one rotation of the pedals. This distance is known as ‘Development‘.
Development is calculated as:
[circumference of the tyre] * [teeth on the big chainring]
[teeth on the smallest sprocket]
Mark out a straight line with a measuring tape for your category:
| Category | Maximum Development |
|---|---|
| Junior / Under 18s | 7.93m |
| Youth A / Under 16s | 6.93m |
| Youth B / Under 14s | 6.45m |
| Youth C / Under 12s | 6.05m |
| Youth D / Under 10s | 5.40m |
| Youth E / Under 8s | 5.10m |
- Ensure the bike is in its highest configuration, smallest restricted* rear sprocket and largest restricted* front chaninring
- Make sure the chain is engaged with the chainring and sprocket
- Check the tyres are inflated to racing pressure
- Position the bike at the starting point on the rollout,ensure that the crank is in bottom dead centre position and aligned with the zero point on your measured line
- Roll the bike backwards, ensuring to stay in a straight line, following the measured line
- Stop the bike once the crank has completed a full revolution and the crank is back at bottom dead centre
- Assess whether the crank is within or over the gear restrictions relative to the marked out measured distance
* Restricted means the smallest sprocket and/or the largest chainring that can be selected. Restrictions are applied by adjusting the high limit screw on the rear and front derailleur to ‘lock out’ ratios that are too high.
So what gears have I got?
Typically full size road racing bikes come with a rear cassette from 12-25 or 12-27, coupled with double chainset with 53 and 39 toothed chainrings. They have 700c wheels fitted with 700x23c tyres, which gives a circumference of 2.099m when inflated to between 90 and 110 psi. From this information we can calculate the maximum distance you can travel for one revolution of the bicycle crank, or the gear ‘development’
[circumference of the tyre] * [teeth on the big chainring]
[teeth on the smallest sprocket]
Development = 2.099m X 53 / 12
Development = 9.27 metres
Other common chainset fitted to full size race bikes are Compacts generally 50 and 34 toothed chainrings and Triples which commonly have 52, 42 and 32 toothed chainrings.
So a gear development chart for a full size road bike with a 12/27 in either compact, double or triple chainset looks like this
But what gears can I use?
Youth A / Under 16 with the limit of 6.93m
From the gear development table for 700x23c Youth A / Under 16 riders would have the green highlighted ratios available. Therefore a good choice would be a 39 tooth chainring with a standard 12/27 rear cassette. This would give a good spread of gears and only require the large chainring locking out for racing.
Oh, but your bike hasn’t got a 39 tooth chainring? Well if you get serious then 39 tooth chainrings are relatively inexpensive and readily available for compact, double and triple chainsets. Fitting requires a special tool so speak to one of the coaches and they will help you find a friendly mechanic or local bike shop to sort it out.
Youth B / Under 14 with the limit of 6.45m
From the gear development table for 700x23c Youth B / Under 14 riders would have the green highlighted ratios available. Therefore a good choice would be a 39 tooth chainring with a standard 12/27 rear cassette with just the 12 sprocket and the large chainring locked out for racing. This setup also gives room for growth if you continue to race as the 12 sprocket can be unlocked when you become a Youth A / Under 16 rider.
Youth C / Under 12 with the limit of 6.05m
For this category we’ll assume a small road race bike fitted with 650x23c tires so using that development table, Youth C / Under 12 riders would have the green highlighted ratios available. Therefore a good choice would be a 34 tooth chainring with a standard 11/28 rear cassette with the large chainring locked out for racing.
Youth D / Under 10 with the limit of 5.45m
Road race bicycles for this catagory are generally mini or junior race bikes and come with 650c or 24″ wheels. The chainsets are usually smaller and the cassettes made up of 8- or 9-toothed sprockets. Below is an example gear development table for a 650x23c tire with a typical 8 speed cassette with either a small double or small triple chainset. The green highlighted ratios are those available to Youth D / Under 10 riders. Therefore a good choice would be a 36 tooth chainring with a 12/26 rear cassette with the 12 sprocket and the large chainring locked out for racing. This setup also gives room for growth if you continue to race as the 12 sprocket can be unlocked when you become a Youth C / Under 12 rider.
Youth E / Under 8 with the limit of 5.1m
Bicycles available for this age and size of rider are diverse. The coaches will help you to set up what every bicycle you have to have a go and participate at this level. However, if you get hooked, then you may be able to safely ride a mini or junior race bike. So, using the gear development table for the Youth Ds above; the green highlighted ratios are those available to Youth E / Under 8 riders.
A sensible choice, should you get hooked, would be a 36-tooth chainring with a 12/26 rear cassette with both the 12- and 13-tooth sprocket locked out, along with the large chainring, for racing. This choice allows room for growth as you move into the Youth D category by unrestricting the 13 sprocket.