Navigating junior gearing and roll outs can be a confusing and time consuming process for parents new to junior cycling. In this blog we hope to help you when navigating junior gearing and roll outs for Under 11’s to Under 19’s.
A bikes’s rollout is the distance the bike travels over one complete pedal revolution and is measured in metres.
Road bikes have multiple gears and hence multiple rollouts.
For racing in Australia a bike’s rollout is measured as the largest rollout available at presentation to officials at the meeting. This is when the chain is on the largest available chain ring and the smallest available sprocket on the rear cassette.
To race on the road at junior level the following rollouts are required.
- U11 & U13 = 5.5 m
- U15 = 6.0 m
- U17 = 7.0 m
- U19 = 7.93 m (26 ft)Most off the shelf bikes will roll over these limits and have to be adjusted to conform to race standards.
Rollouts can be achieved by:
- locking out (disabling) one chain ring (front) and/or one or two of the smallest sprockets onthe cassette (rear) by adjusting the front and/or rear derailleurs; or
- fitting a combination of chain rings and sprockets that achieve the desired maximum rolloutwithout disabling either of the derailleurs. That is, the full set of gears on the bike are available.
Lockouts are the most common way of achieving a legal rollout and this method is allowed at local race meetings. However, at Road National lockouts are not allowed and method 2 above has to be used.
To Calculate a Rollout on a Road Bike
There are 3 variables that need to be measured.
- The number of teeth on the largest chain ring (see photos).
- The number of teeth on the smallest sprocket on the cassette (see photos).
- The rear wheel size (see photos). Most wheels on recent road bikes have a standard diameterand the main variable is the width of the tyre (distance between the wheel rim and the outer tyre edge). This is usually written on the side of the tyre and must be used in calculating a rollout.
Enter the figures into an online calculator to find a rollout. There are several online calculators and they don’t always give the same result.
Also, beware that calculated rollouts rarely equate to real-world rollouts. If you calculate your bike to be very close (1-5 cm?) to the legal rollout be aware that the bike could roll over the legal limit once you have made the adjustments.
Here are a couple of online rollout calculators for navigating junior gearing and roll outs.
Contributors Tim Blake & Amanda O’Connor