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The toothed belt has won. If you scroll through the websites of many bicycle manufacturers, you will hardly find a bike with hub gears without the low-maintenance belt drive - regardless of the price range. Two years ago, things were very different: the Gates belt characterised high-quality transmissions such as Alfine 11, Rohloff and Pinion. It was difficult to find a belt-driven bike for less than 1500 euros. In the more affordable range, the classic metal chain was usually still used for power transmission.
Cheap and good?
In the 2020 season, the affordable CDN version of the Gates belt is gaining widespread acceptance. In contrast to the more expensive CDX belt made of polyurethane, which is developed for the most intensive loads, the simpler CDN version is aimed at more moderate areas of use: it is the cheaper choice for everyday riders who do not cover 10,000 kilometres a year and is therefore clearly the better choice for inexpensive bikes. This is because a bike with a low-maintenance CDN belt drive is priced between 1000 and 1500 euros.
The belt itself is made of polymer plastic; as with its more expensive counterpart, carbon fibres embedded lengthways ensure that the belt is absolutely tensile and does not stretch. Compared to the chain, manufacturer Gates claims a two and a half to three times longer service life for the CDX drive and one and a half to two times longer service life for the simpler CDN drive. Even after wear due to intensive use and high pedalling loads, a Gates belt, unlike a bicycle chain, does not become longer. This is due to the fact that friction between the individual metal components of the chain inevitably causes abrasion, which constantly increases the fit of the rivet, link plate and roller. Many small worn chain links add up to a total elongation of easily 10 millimetres. However, chain links that are just a few tenths of a millimetre longer gnaw at the teeth of their sprockets and remove material there too.
With the belt, on the other hand, there is no internal friction and therefore no internal wear thanks to the compact material. Even on the outside, on the tooth profiles of the pulleys, wear should be negligible thanks to the carefully matched material properties of the belt and drive pulleys. Gates therefore recommends that bicycle manufacturers use a measuring device to adjust a new drive so that the belt tension is in the upper green range of the permissible range. The running-in process during the first hundred kilometres causes the surfaces of all drive components to roughen slightly and adjust to each other. During the scheduled initial inspection, the specialist dealer can check the belt tension again. Ideally, it should then be centred in the green range. And then never change again.
Optimisation on the Rieman drive
But a drive system is not just made up of the belt. The pulleys on the crank and rear wheel also contribute to the service life of a drive system. In the CDN system, a "chainring" made of composite plastic has proven its worth here. As the forces are distributed over about half of the 46 or 50 teeth, wear remains low. The situation is different on the rear wheel: Initially, Gates also fitted plastic discs there, which were mounted around a metal carrier. However, this did not prove successful because fewer teeth were subjected to significantly more load and wore out more quickly. This is why current CDN sprockets are made of stainless galvanised steel as standard. For the maximum-life CDX version, Gates uses hardened aluminium on the crank and stainless steel on the rear wheel.
The right belt tension is crucial
Just like a chain, the belt must also run under a defined pre-tension so that it does not jump over or off. The bike manufacturers solve this problem on almost all test bikes with sliding axle pieces on the rear wheel. It has taken several model years to develop usable, cost-effective designs. The tension only needs to be adjusted once, as the belt will not stretch later. If there are also adjusting screws at the dropout, the belt tension can be adjusted sensitively and optimally and the wheel centred at the same time. An eccentric on the bottom bracket and classic dropouts, such as on the Kalkhoff and Raleigh bikes, both of which come from the Derby Cycles factory, are also a simple and robust solution. The eccentric should be removed, cleaned and re-greased every one or two years to prevent it from corroding.
Gears in a can: advantages and disadvantages of hub gears
The gear hub is an essential element of long-lasting, low-maintenance drives. Hermetically sealed against moisture and dirt, its complicated mechanics always work under the same optimum conditions, including lubrication. The test field is dominated by the inexpensive Nexus hub and the slightly more expensive Alfine hub, each with eight gears. The inner workings of both models are the same, only the cover of the Alfine is a little prettier. The internal mechanics should be removed every 5000 kilometres or once a year and immersed in an oil bath - a job for the specialist dealer.
The eight gears are sensibly tuned, but have pitfalls for sporty riders. In the T-700 from Fahrradmanufaktur, the only outlier is an Alfine 11, here combined with a chain drive. The eleven-speed hub has regularly stepped gears overall, but packs its three additional gears at the upper end of the spectrum - where only a few cyclists really need them. All hubs have the weakness that they only offer a few small gears for longer or steep climbs. So if you have to ride uphill and downhill every day, you won't be happy with Shimano hubs.
Every belt frame requires a belt lock in order to be able to install the closed belt. Frame manufacturers usually use a divisible seat stay on the right-hand side, which is bolted together with stepped connecting pieces to form a positive fit. This means that the flow of force within the frame construction is hardly disturbed and the connection can be easily opened and securely closed again. The steel frame of the T-700 has no belt lock and is therefore chain-driven.
What remains to be done in terms of maintenance
For maintenance, it is sufficient to clean the belt and the sprockets regularly with soap and water and to remove any embedded dirt from the belt groove. A belt drive may squeak under certain circumstances: A little silicone spray is usually enough to quiet it down again. It may often be necessary to slightly readjust the tension of the shift cable using the adjusting screw on the shift lever. On an eight-speed hub, the yellow markings in reference gear 4 (Alfine 11: gear 6) must match. If everything is optimally adjusted, bicycles with low-maintenance hub gears can be ridden quite lazily - but always nice and crisp.
Gears and gradations - the unfolding
Since eight out of nine test bikes have an eight-speed hub, we took a closer look at these models from Shimano's Nexus and Alfine series. On the Raleigh Nightflight, we calculate the gear range for each gear as an example in the table below. The wheel (tyres: Schwalbe Marathon Supreme 42-622) has a circumference of 222 centimetres, the primary gear ratio is 50 teeth at the front and 22 at the rear. Multiplied by the internal hub ratio per gear, this gives the distance travelled with one turn of the crank in the respective gear.
You can clearly see that the values are already very high in first gear: a 3x10 derailleur gear system would have values well below two metres in first gear - good if you have to tackle longer climbs. The frequently used gears are between around 14 and 18 per cent apart. You can feel the difference as a clear shifting step, but still close enough to each other that you can maintain your speed well. A large jump of 23 per cent between gears 5 and 6 lies in the middle of the heavily used range. This throws the cyclist off the pace.
All low-maintenance wheels at a glance
- BERGAMONT VITESS N8 BELT*
- GIANT ANYTOUR CS 1
- VSF FAHRRADMANUFAKTUR T-700
- R RAYMON TOURRAY 6.0 GENT
- RABENEICK TX7C
- RALEIGH NIGHTFLIGHT PREMIUM
- STEVENS COURIER LUXE GENT
You can download the complete test of the low-maintenance bikes from MYBIKE 02/2020 as a PDF below the article for a fee.
Why not free of charge? Because quality journalism has a price. In return, we guarantee independence and objectivity. This applies in particular to the tests in MYBIKE. We don't pay for them, but the opposite is the case: we charge for them, thousands of euros every year.
