Why does my bike have so many gears when my car only has 5 or 6?! This is a commonly asked question, and the sheer number of gears and combinations can be confusing for many. It all relates to how we pedal, and how much power and torque we can create at the cranks.
When we pedal, we apply a force to that pedal, and this creates torque – a ‘twisting’ force around the bottom bracket axle. This is then transferred to the rear wheel through the gearing and drives you forward. When we encounter a hill (fighting gravity), or are starting from a standstill (accelerating), we require more torque at the rear wheel. We can pedal hard… or we change down a gear. If it gets steeper, we change down again. Basically, you are turning the cranks many times for one wheel revolution, increasing your mechanical advantage. The gears act to increase or decrease the torque at the rear wheel.
But on the flat and downhill, if we stayed in the low gear our legs would have to spin like crazy! This is when we change up a gear. We now don’t need large levels of torque at the wheel, we need it to turn – fast. In a high gear, one turn of the cranks can turn the rear wheel several times.
We like to pedal at a fairly uniform rate, usually between 50-100 turns of the cranks per minute (cadence), and to push down on the pedals with a preferred force. Your gearing allows you to keep yourself in your comfortable ranges as the conditions and hills vary, rather than have to push really hard on the pedals, or spin very fast. And this is why we have a lot gears – if we only had a few then the gaps between them may be too large to allow you to fine tune your output. Different types of bikes will have gear ranges to suit the terrain they are used on and, with the advent of very large range rear cassettes, the front gearing can often be reduced to just a single ring.
A car engine can operate effectively across a broad range of engine revolutions – from about 1000 rpm to over 10000rpm on high performance models – and can produce high levels of torque across that range. Your legs, however, cannot – and this is why cars have fewer gears.
So how does that relate to your eBike? Our hub motors give you additional torque at the rear wheel. By selecting one of the assistance modes on your display, you can add in the perfect amount of extra oomph that you require.