Are you ready for the belt?

In search of the best power transmission

The belt drive system is nowadays chosen over a chain drive bij multiple cyclists. Think of Hera van Willick, who has cycled across Europe to Asia and through Alaska, crossing the Arctic Circle all on her Santos TravelMaster 2.6 with Gates Carbon Drive™ belt and a Rohloff gear hub. Hera: “It’s a rugged, stiff, compact bicycle. Apart from cleaning it, checking the break pads and pumping the tires, there’s pretty much nothing I have to do in maintenance”.

The applicability of the belt for bikes is very wide. Brose, for example, started to use the belts in its E-bike motors instead of gear wheels. This results in a motor that is a lot more quiet than its competitors. A positive side effect is the power to weight ratio and its small dimensions that make integration in E-bike frames easier for the manufacturer.

Two leading belt manufacturers in the bicycle industry are Gates from the U.S. (since 1917) and the German tire company Continental (since 1871). Continental’s first bike products were solid tires for bicycles in 1871 and they introduced the first pneumatic bicycle tires in 1892. It was Continental in 1943 who patented the tubeless tire system for cars and trucks, nowadays very often found on mountain bikes. More and more road bike fanatics consider to apply tubeless tires.

We may conclude that since 2007 the applicability of the belt on bikes is growing fast, let’s say really fast. Today both belt brands have many belt and sprocket types in their catalog. So there is a system specially made and designed by Continental for E-cargo bikes that makes use of a 12mm wide carbon belt and aluminium and stainless steel sprockets for the massif loads these bikes carry every single day. On the other hand Gates makes a system called CDX SL and uses aluminum for the rear sprockets to minimize the weight of the total drive train. Both brands also have systems applied on city bikes, mountain bikes, gear hub road bikes, globetrotter bikes, folding bikes and so on.

Back in time: in search of the best power transmission

Already for many years we make use of external power, like water mills, wind mills and steam engines in which we aim for the best power transmission. Babylonians used chains for the first time for water drawing machines. By 1430 the link chains are shown in the drawings of Leonardo da Vinci.

During the industrial revolution, the need of power transmissions was on its highest. By that time, the steam engine was used in almost every factory and the belts made of leather, hemp rope and iron strings were used to transport the power of the steam engine to the machines in the factory.

The brothers Charles and Hazel Gates pooled their savings in 1911 and bought The Colorado Tire and Leather Company. In 1917 the company started to phase out the leather in favour of rubber. In that same year their brother - John Gates - developed a belt made of rubber and woven treading, nowadays known as a V-belt due to its shape. This great invention leads to the replacement of the common leather and hemp rope belts, which were until that moment used in factories around the globe.

Around 1880, the first bicycles were performed with link chain drives. Something completely different for those familiar with Boneshaker bicycles, which did not have one. Soon the link chain was taken over by various bicycle manufacturers and until 2007 it was dominant to other power transmissions used on bicycles.

In 2007, the year that Gates introduced their Gates Carbon Drive™ system, there was a reshuffle noticeable at bike brands like Trek and many others by starting to use a belt instead of a chain.

In 2010 Gates introduced the CenterTrack system called the CDX that made it harder for the belt to run off of the sprockets. This invention done by Wayne Lumpkin made the belt system even more reliable and durable.

Nowadays belts are made of different types of polymer, carbon fibers and elastomer. Depending on the brand and type, the belt has its own thickness and width. The belt sprockets are mostly made of stainless steel or aluminum, although composites are used in a lower price range or to save weight when durability is less important. The life cycle is about 25,000 kilometers on a belt and a pair of sprockets, depending on when, where and how you use the bike. For example, the life cycle of a belt and its sprockets on a heavy cargo bike with a Bosch e-bike motor is shorter than when used on an ultralight sports bike.

Although the belt is refined and a progressive option for the chain, the belt drive system has its downsides. A belt can break, snap or worn out during its lifetime, just like a chain. When the belt breaks, you should replace it by a belt with exactly the same amount of teeth as you had before. Because the belt drive is pretty new, these parts are not always available in bike shops. The availability of these parts can be seen as the achilles heel of the belt drive system nowadays.

By: Fietscontent (fietscontent.nl)