Gearing Questions

Been playing around with the gearing for my lads kart. Is it better to have a larger or smaller engine sprocket, or does it make no difference if the gear ratio is the same.

e.g. If I use a 74 rear sprocket with a 10 engine sprocket that gives basically the same gear ratio as an 81 with an 11. Does it make any difference which combo I use?

The ratio is what matters.

The ratio sets how many turns of the engine it takes to make one turn of the tire.

The inertia of the kart, as seen by the engine is:

(1/ratio) ^2

Rotational acceleration = Torque/inertia

The sprocket and gear teeth only enter into these equations as the ratio.

This has been debated and the general consensus is that ratio is ratio and that bigger or smaller sprocket doesn’t make a measurable differenc to us kart folks

However, now that I think about it, big sprockets and kerbs aren’t a good fit. So maybe there are times when this matters in terms of not having your chain and sprocket whang kerb.

In terms of power wont make much difference but should get better driver and chain life out of an 11 driver.

Thanks guys, really helpful. I think I’ll stick with the 11 and go from their!

It’s not just about ratios, be mindful of kerbs also as @Bimodal_Rocket intimated.

A smaller rear sprocket equals less possibility to snap the chain if the lad clips a kerb with it.