Not sure what gearing or roll out you should be running?
The industry standard calculator can be found at:
https://bmxultra.com/gear-calculator/
Here you can select your tyre brand, size, chainring size and sprocket (rear cog) size to get your “gear inches” or rollout.
What should I aim for?
There isn’t a consensus on what gear inches you should aim for, but as a starting guide I would recommend the following:
- Micro frame (18 inch wheels) - 45-47 inches
- Mini frame - 47-49 inches
- Junior frame - 49-52 inches
- Expert frame - 50-53 inches
- Pro frame - 52-55 inches
Your actually gearing is very rider specific and will depend on their style, size, power and approach. Generally a lower gearing will help with the first few cranks and so faster gate and hill times. A larger gearing will give a faster top end speed. BMX racing is a sprint sport (race) so a balance must be struck. There is little to be gained gearing for a time trial lap PB when in practice this means you are in the middle of the pack on the first straight and never get the opportunity to reach your potential top speed.
Your crank length will also come into play. A longer crank length will make the first few cranks easier but a smaller crank length may help with cadence and leg speed.
In summary, gearing is very rider specific. Watch the rider closely, are they “spinning out”, pedalling at full speed but not gaining acceleration on the track, a sign you need to move up in gearing.
What next?
If you want to adjust your gearing the easiest way is to change your chainring. Take a look at one of our more popular products here.
