Unique Bosch motor cover on Trek's new 120mm travel full-suspension electric mountain bike


So, a new full-suspension e-bike from Trek? What do I need to know?

The Powerfly + range consists of three full-suspension models (and a few hardtails), the FS 9, FS 7 and FS 5. All three use a 120mm travel, aluminium chassis running 650b wheels and the Bosch motor system. According to Trek’s engineers, carefully configured geometry, kinematics and specifications make this the best electrically assisted full-suspension bike on the market.


Did you say custom motor covers? What are the advantages of those?

Bosch builds the go-to system for e-mtbs. It’s used by all the big players: Hai Bike, Cube, Scott… But the motor comes packaged in a bulky plastic casing that usually means manufacturers have to compromise on pivot location and chainstay length, ending up with massive back ends and suspension designs that may not be fully optimised to the small front drive sprocket. Trek’s engineers cracked open the box, realised there was unutilised space that would allow them to run shorter chainstays and a higher pivot, and decided to design and mould their own casing. The result, Trek claims, is a better main pivot position and chainstay length around 15mm shorter than its competitors without the need to use a complex idler system. Plus, the motor covers also get a built-in chain guide, belly armour, integrated cable routing and all-important bottle opener.


Did you say the geometry and kinematics are altered too?

Yes. Trek’s engineers found that the smooth, consistent torque output from the Bosch motor reduced pedal-induced bobbing and required less compression damping. So, the RockShox Monarch shocks fitted to the Powerfly + typically run about 30% less compression damping than those found on bikes such as the Fuel EX and Remedy, which should allow the bike to gain grip and track the ground better.


Aren’t e-bikes cheating?

Perhaps for you and I, the idea of an e-bike goes against the whole idea of taking a bicycle off-road, but as the population ages, and people become more active in their later years, so e-mtbs could find a place. Certainly, in Germany, Austria and Switzerland they are ‘a big thing’. Enough to make manufacturers such as Trek sit up and take notice. And we can definitely see the potential of e-bike fleets at trail centres, where whole families could head out for a full-day’s mountain bike ride with only modest fitness.

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Details of the three models are above. We’ll bring you full specs, prices and geometry just as soon as we get them, and look out for a first ride on the Powerfly + in the April issue of MBR.