Gear changes on the bike: The transmission programme

derailleur gears

Since derailleur gears found their way onto bicycles in the middle of the last century, they have become extremely differentiated. What all variants have in common is a more or less open chain, which is shifted by the front derailleur and the rear derailleur between cogs of different sizes. This design principle is so variable that the finest gear steps, as on a racing bike, are just as possible as a huge difference between the smallest uphill gear and the longest gear ratio on a mountain bike.

One, two or three cogwheels are possible at the front, while at the rear there are currently between nine and 13 cogwheels in the most common groupsets. The price level normally increases with the number of rear cogs, because the more densely the rear cogs (sprockets) are packed, the more precisely all the shifting components have to function.

Gears with three chainrings at the front - especially the high-quality Shimano Deore XT 3x10 - are practically only common on touring or touring bikes. It takes some experience to shift the gears in the right order, as not every rear cog is compatible with every front cog. Too much chain skew worsens the function and increases wear. In recent times, derailleur gears with only one cog at the front (chainring) and eleven to 13 sprockets at the rear have become increasingly popular. They are easy to shift, but sometimes have large gear ratio jumps between individual gears.

Single derailleur gears are common on e-bikes - the motor power compensates for any missing uphill gears. Derailleur gears can be combined with both centre motors and hub motors. They also shift reliably under load.

+ large gear spread that can be changed by changing the sprocket

+ Relatively light and inexpensive

- Maintenance requirements and wear

Gear hub

It's hard to believe, but hub gears with their many cogwheels inside are older than derailleur gears. Here, the gears are hidden in the rear hub and only the chain wears out in the open. Now that Sram has stopped producing gear hubs, Shimano hubs with five, eight and eleven gears are mainly available in the mid-price market. The advantage of these hubs is their low maintenance. They are also available in combination with a belt drive for bikes from around €1,000, which makes the drive almost maintenance-free. Their disadvantages are their poor shifting behaviour under load (you have to take pressure off the pedal briefly when shifting) and their somewhat higher internal resistance compared to a well-maintained derailleur system. A particularly high-quality and durable hub gear is the German Rohloff hub with 14 gears, which covers roughly the gear range of a mountain bike derailleur. The continuously variable Enviolo hub is also used in pedelecs in particular. The motor makes you forget that it is heavy and runs with a little more resistance. It can be shifted under load and is also available in an automatic version. Hub gears cannot be combined with rear hub motors on pedelecs.

+ Low maintenance

+ easy to operate

- mostly limited mountain suitability

Bottom bracket gearbox

If you're not familiar with it, you might mistake it for a motor: The Pinion gearbox sits directly on the bottom bracket like a mid-engine. This comparatively new gear system from Germany has 9, 12 or 18 regularly stepped gears and is designed for a long service life. If you want to ride it, you need a frame specially built for it. It only works on a pedelec in combination with a hub motor.

+ Very low maintenance

+ Even gear steps

- Expensive and heavy

Special frame required