All geared up!
We read a lot in bike magazines about ‘changing the gearing’, but what does it mean? Motorcycle engines tend to make their best power at high revs, but the highest road speed at which that power is capable of propelling the bike means that the rear wheel is rotating more slowly than the engine.
For example, at 100mph the rear tyre will typically be rotating at about 1350rpm. So if the engine needs to be revving at 6000rpm at this speed, the ratio between the two has to be 4.43 to 1, provided by gears and the drive chain sprockets.
Trouble is you’d never be able to pull away from a standstill with this ratio without mercilessly slipping the clutch, so a selection of lower ratios are provided, which is why bikes have gearboxes with up to six cogs…
These days, the so-called gearing of a bike is more a matter of taste than the basic theory. Most bikes (even A2 learner machines) are capable of reaching 100mph
