Electric Mountain Bikes: info and guide

Until just a few years ago, the market for ebikes was made almost exclusively by city ebikes, meant mainly for older people. In the last few years the situation has changed a lot. Ebike producers have started to try to appeal to new kinds of users, younger, and eager to practice some sport. In just a few words, this is how electric mountain bikes were born.

E-mtbs can be a great way to discover nature, allowing many people to pedal on paths and dirt roads with a much lower environmental impact than that produced by an off-road motorcycle. MTB purists are sceptical, and criticize the fact that many people can now have access to mountain paths that were once reserved to those fit enough to reach them. Actually, you just have to try an e-mtb (especially the European ones, with a 250W motor) to understand that the motor just gives some help, but you have to pedal all the same, especially uphill.

Trained bikers with advanced skills can still profit from electric mountain bikes: they can reach peaks and places that were once off-limits, and they can have fun in controlling the bike even when going uphill (sometimes you even have to brake uphill before corners!). Those who simply enjoy riding their normal mountain bike on terrains of average difficulty without the need of advanced riding skills can have more fun, having the small electric motor help them go a little further or a little higher. The same ascent, done on asphalt or on a dirt road, is much harder in the latter terrain, and therefore the assistance of the motor is much more useful.

The electric mountain bike market is now very varied, and you’ll be able to find e-mtbs with 26″, 27,5″ (also in the Plus version) and 29″ wheels, as well as front-suspended e-mtbs and full-suspended versions. Even electric fat bikes are easier and easier to find.

Electric components of e-mtbs

Just like any other ebike, electric mountain bikes have 4 main electric components: motor, pedalling sensor, battery, controller. We will now present what these should be like specifically on an e-mtb; for a more complete discussion you can follow the links provided below.

Serious electric mountain bikes all have a bottom bracket motor (that is a central motor, between the pedals). Central motors have a series of advantages which make it better suited to an e-mtb. First of all it allows for a more even weight distribution, therefore enabling a better handling of the bike. MTB wheels are subjected to a lot of stress (holes, roots, stones…): better not weigh them down with the 3-4 extra kgs of a hub motor. In case of a puncture, a central motor allows you to change the tube very easily, just like on a normal mtb (on the contrary, if you have a hub motor you’ll have to deal with the cabling when changing the tube). Because they act directly on the transmission, central motors allow you to keep a better control of the power delivered by the motor, especially when coupled with a torque sensor (see below); moreover, because they can take advantage of the bike’s gearing, central motors can work at higher and therefore more efficient RPMs, which can make a lot of difference especially in steep ascents, where a hub motor – forced by the low speed of the bike to work at lower RPMs – can turn very hot and even stop working until it cools down.

You can’t do without a pedalling sensor on an electric mountain bike. There are two kinds of sensors: a simpler one which just tells whether the pedals are turning or not, and a more complex one, which can “understand” how hard you are pedalling. This is called a torque sensor, and it senses whether you are just strolling along or really pushing hard on the pedals, adjusting the power delivery accordingly. In this way, torque sensors guarantee a very natural feeling, as the motor of the e-mtb follows our instinct and delivers a higher power just when we need it. We think that an e-mtb should have this kind of sensors (torque sensor), because it makes the handling of the bike much more natural, something very important when riding offroad amidst roots and stones. All the main e-mtb systems (Bosch, Yamaha, Impulse, Brose…) are based on torque sensors.

The battery is the reserve of energy to the motor. Modern electric mountain bikes use lithium-based batteries, light and with a high capacity. The range of an ebike is usually measured in terms of kilometers, but on an e-mtb it makes much more sense to measure it in terms of meters of altitude. We suggest you do not go below about 400Wh of capacity for a battery; this should allow you to cover about 1000 meters of altitude. Last, the position of the battery on the bike frame is also very important: batteries can be quite heavy (about 3 to 5 kg), and its position has an influence on the handling of the bike; the best position for an electric mtb is surely on the sloping tube of the frame. Other positions determine a longer chainstay (and therefore a worse handling) or a higher weight).

The last fundamental electric components of an e-mtb are those that are used to control its functions: displays and buttons. When you pedal off-road, it is important to always be in full control of the bike: these components must therefore conform to two standards: buttons must be positioned within easy reach of the hands: you should be able to push them without moving the hand from the handlebars, and ideally without even looking at them. The display should be easily readable. You can achieve this by positioning the buttons very close to the hand, and the display in the centre of the handlebars. The control system usually allows you to select the level of assistance: we advise to have at least four of them, in order to precisely manage the power delivered by the motor (and therefore the energy consumption). Latest generation systems integrate a colour display with gps info. Some have decided to make a completely different choice, as for instance Specialized with its Turbo Levo that does not have any display or buttons.

Electric Mountain Bikes: what’s on the market

The e-mtb “revolution” has taken some producers by surprise: while some producers offer carefully thought bikes, others have rashly adapted to the new trend, mounting on mtb frames motors and batteries that are not perfectly suited to this use. The situation is rapidly changing, and all serious producers nowadays offer well designed e-mtbs, with a wide range of motors. The real problem is the actual availability of the bikes: having to wait for months for an e-mtb is not rare

Bosch systems

The first “modern” electric mountain bikes were produced with Bosch motors by Haibike, a producer that still dominates the market (they have just presented their Xduro3 series for 2016). Other producers that sell e-mtbs with Bosch motors are Cube, KTM, Conway, Trek, Lapierre, Matra. Bosch e-mtbs are probably the most widespread, though the competition is getting stronger and stronger. Here is our in-depth article on Bosch 2016 systems: as you can read there Bosch has just developed a new motor able to deliver a higher torque, better suited to an off-road use.

Yamaha systems

Yamaha is the biggest competitor for Bosch. Even here Haibike dominates, with its Sduro range. E-mtbs with Yamaha motors are appreciated for two main reasons: the high torque, and the fact that they can be used with a dual chainring, to have a higher range of gears.

Impulse Focus systems

Focus, another big producer of mountain bikes, has instead chosen to develop an in-house system: it’s a great motor based on a torque sensor. You can read our test of a Focus e-mtb to get to know it better. Focus has just presented a new improved version for 2016 known as Impulse Evo.

Bafang systems

Bafang dominates the sector of “electrified” mtbs, that is those that are born as “normal” mountain bikes and that bikers decide to electrify afterwards. Bafang’s central motor is one of the most used for this purpose. It uses a simple pedalling sensor instead of a torque sensor, but because it acts directly on the transmission, the result is good anyway. Bafang is about to introduce a new version of its motor, known as Bafang Max Drive: as far as we know this should be based on a torque sensor, and should be able to deliver a high torque.