Few questions are as controversial as the durability of e-mountainbikes. Time and time again, we receive emails from readers reporting smoking motors, extinguished batteries, chains breaking in rows or sprockets wearing out in fast motion. This contrasts with the results of our online survey from 2019. 80 per cent of participants said they were satisfied with the durability of their e-MTBs. Tenor: The wear is appropriate for the area of use. A very positive result that we would not have expected. Not because we think e-mountainbikes are overly vulnerable. Rather, because we thought that the psyche plays tricks on many e-bikers.
"Subjectively, the wear on all components is extremely high," says E-MTB designer Lutz Scheffer. "However, this is primarily due to the fact that bikers with an e-motor ride a lot more, especially more metres in altitude and more demanding trail kilometres." Scheffer himself clocks up around 100,000 metres of e-MTB elevation gain per year - so he knows what he's talking about. The difference is even more drastic for dealers and manufacturers, as completely new groups of buyers are entering extreme terrain thanks to motor support. "Mountain bikes used to be purely sporting equipment, with hardly any heavyweight people travelling in the mountains. The load on the bikes and components is not only increasing due to the higher weight of the bikes themselves, but above all due to heavier riders," says bicycle expert Dirk Zedler. In plain language: More often than normal MTBs, e-MTBs have to carry 100-kilo riders safely down the steepest hills. And commuters who cover many metres in altitude every day in wind and weather also want to be kept happy in the long term.
In this endurance test, we analysed the neuralgic weak points of the E-MTBs and collected tips for lasting riding fun.
We also tested these three bikes in continuous use - the links to the results can be found at the end of the article:
- Focus Raven² Pro
- KTM Macina Kapoho 274
- Canyon Spectral:On 7.0
PROBLEMS AND SOLUTIONS
PROBLEM ZONE CIRCUIT
The sprocket and chain are the classic wear parts on a bike, including an e-mountainbike of course. With a motor, the load is significantly higher. The power of the motor gives every hobby biker a start like cross-country hero Nino Schurter, which puts a strain on the chain, sprockets and chainrings. "Chain wear and sprocket melting is already a huge issue with e-mountainbikes," confirms graduate engineer Dirk Zedler. In addition to the power plus, there are other sticking points. The motor pushes less sensitively than experienced bikers can. As a result, gear changes often take place under full load. In addition, the motor overruns, i.e. continues to accelerate when the cranks are already stationary. As a result, chain jams or sticks in the drivetrain of e-MTBs can lead to failures such as torn derailleurs or chain breaks more quickly.
"That's why I always have a piece of chain and a chain lock with me," says frequent cyclist Lutz Scheffer. He also advises using cassettes with steel sprockets. "Aluminium sprockets only have a short life on an e-MTB. The rule here is: cheaper is better." The only explicit E-MTB drivetrain, Srams EX1, also relies on a cassette with eight steel sprockets for this reason. "Unfortunately, this has not really established itself on the market," says Zedler and appeals to e-bikers to look closely at their needs when choosing their bikes and components. Frequent riders should invest in durability. Incidentally, Bosch drives are a special case. "The super-small drive sprocket puts extreme strain on the chain, a real chain eater," says Zedler. After around 1000 kilometres at the latest, it's over.
T I P P S
- Cheaper is better: Steel sprockets are significantly more durable than aluminium sprockets.
- Locking instead of riveting: Chain locks are less prone to failure than rivet pins and therefore more reliable under high forces on the E-MTB.
- Changing the chain regularly prevents annoying defects on tour.
- If possible, do not shift in turbo mode! Also, only change one gear at a time, do not shift over several sprockets under load.
PROBLEM AREA ENGINE
The motor is the centrepiece of every E-MTB. It is dangerously exposed when used off-road. Splash water, deep puddles or streams have just as much of a free rein as stones, rocks and root carpets. "The engines themselves are surprisingly tough," says designer Scheffer reassuringly. But that doesn't mean that bikers should put their bikes through everything without hesitation. Because there is one clear weak point: the seal on the bottom bracket shaft. Due to its design, it can never be completely watertight. Splash water and dirt are not a problem in themselves. The crux of the matter is cleaning. If you work with high water pressure, dirt can wash past the seal and into the inside of the motor. Bosch Performance CX motors were increasingly affected by this problem - the gearbox ran rough, seized up or rusted. The engine giant has now made improvements.
"It is striking that city and trekking e-bikes have almost no problems with drive damage. In the mountain bike sector, you hear it again and again. This leads to the suspicion that this is clearly related to the issue of cleaning," says Zedler and puts the onus on consumers. Steam cleaners are absolutely taboo on E-MTBs. In the bottom bracket area, you are on the safe side with a bucket of water, sponge and biodegradable detergent.
PROBLEM AREA BRAKES
"It's actually crazy what thin brake discs e-mountainbikes are equipped with." With these words, bicycle expert Dirk Zedler opens his plea for more durability in e-MTB brakes. "If you are vigilant and change them regularly, this is usually not a big problem," he continues. "But the costs and effort are immense." This doesn't have to be the case, because more stable and durable brake discs for E-MTBs can be implemented with little additional effort. The low additional weight is hardly noticeable on e-bikes that are already heavy. Scheffer's demand goes in the same direction: "I would like to see larger brake discs for the future of e-MTBs. 220 millimetres at the front wheel, 200 at the rear. And not too thin." Both suggestions would have the positive side effect of improving braking performance and stability. There are already products on the aftermarket that fulfil these requirements, but you have to search for them for a long time. Bike manufacturers have so far favoured standard series products.
A negative example is Shimano's Ice-Tech discs (light version, there are also Shimano discs made of steel), which are based on an aluminium/steel sandwich construction. Practical experience with the E-MTB and the tests of our sister magazine BIKE have shown that these aluminium brake discs are unsuitable for extreme use. In addition, the test bench tests in the BIKE laboratory have shown that the rather thin brake discs from Sram (1.85 mm) and Shimano (1.75 mm) give up the ghost much earlier than the thicker models, e.g. from Magura (1.95 mm) or Trickstuff (2.05 mm). The following also applies to brakes: Realistically assess your personal requirements. Heavy riders who ride a lot in the mountains should pay just as much attention to robust material as people who are travelling with heavy luggage or who cover a lot of vertical metres every day. If you use your e-MTB more occasionally on flat terrain like a normal bike, you will be less affected by the problem.
T I P P S
- If you clean improperly, you risk damaging the engine! Therefore: Hands off the steam jet! The seals on the crankshaft are the engine's weak point.
- Always brake discs and new brake pads cleanly, this reduces wear enormously.
- Always take Erstaz brake pads with you on tour so that you don't have to change the pads prematurely.
- Do not use lightweight brake discs or aluminium constructions for E-MTBs.
Florentin Vesenbeckh
Editor CvD
