Full Suspension.
Full Power.
Real Trails.

There's a conversation we have regularly in the shop. Someone comes in riding a Powerfly+ hardtail, they've been on it a year, they love the motor, they love the Bosch system — but the trails are getting rougher and the descents are getting longer, and they want more. The answer, more often than not, is this bike.

The Trek Powerfly FS+ 4 Gen 4 is the entry point into Trek's full suspension e-MTB range. It shares the same Bosch Performance Line CX motor as everything above it in the range, adds 130mm front and 120mm rear suspension via RockShox, and wraps it in Trek's Alpha Platinum Aluminium frame with the RIB 2.0 removable battery system. At £4,000, it sits at the base of the FS+ range — but it doesn't ride like a base model.

The Case for Full Suspension

It's worth being clear about what full suspension actually does on an e-MTB, because it's easy to assume it's just about comfort. It isn't — or at least, not entirely. Rear suspension keeps your wheel in contact with the ground on rough terrain, which means traction when you're accelerating out of technical corners, stability on loose descents, and confidence when the trail throws something unexpected at you.

The Powerfly hardtails are brilliant bikes for the right rider. But once you're regularly riding trails with roots, drops, or loose over hard surfaces, you start working against the bike. The FS+ 4 removes that friction. The RockShox Deluxe Select rear shock and Recon Silver RL fork aren't the most exotic components in Trek's catalogue, but they're properly set up for the intended riding — trail use at mid-speed, not enduro racing. They do exactly what they're supposed to do.

One thing experienced riders often note about the Powerfly FS platform: the Bosch CX motor changes how full suspension feels. On a conventional full suspension bike, pedal bob can be a nuisance on smooth climbs. With the CX motor delivering power smoothly through the cranks, and with Trek's ABP (Active Braking Pivot) suspension design separating braking forces from suspension movement, the rear end stays composed and active without wasting energy. It's a genuinely clever piece of engineering that matters on long climbs.

What the Bosch CX Actually Delivers

If you've read our Powerfly Buyer Guide, you'll know we go deep on the motor question. The short version: Bosch Performance Line CX is the best motor in the Powerfly range, and every FS+ model gets it. There's no compromise here at the bottom of the FS+ ladder.

100Nm of torque is a significant number. On a steep West Sussex bridleway in wet October conditions, it means you're choosing your line, not fighting to maintain momentum. The eMTB mode is where most riders spend their time — it reads your pedal input and adjusts assist automatically, which means you don't spend the ride fiddling with modes. It just responds.

The 600Wh PowerTube RIB 2.0 battery is integrated cleanly into the downtube and removable without tools — meaning you can take it off the bike for charging, lock it separately, or swap it out for travel. The RIB 2.0 generation is notably rattle-free, which matters on rough terrain where older battery systems would clatter. It's also compatible with the Bosch PowerMore range extender, adding up to 250Wh if you want to push further.

Range on the FS+ 4 in mixed use — a mix of eMTB and Tour modes, decent trails, some flat — realistically sits around 35–50 miles depending on your weight, the terrain, and how hard you push it. Longer than most days out on the South Downs. If you want to push further, the 800Wh version of the FS+ 4 is available at £4,250 — same bike, bigger battery, no other changes needed.

Is the Powerfly FS+ 4 Right for You?

The FS+ range sits between the Powerfly+ hardtails and the Rail full-enduro models. Understanding where the FS+ 4 sits within that is the most useful thing we can tell you.

The Honest Take

The most common question we get about the FS+ 4 is whether to step up to the FS+ 8. The 8 adds an FOX suspension package, SRAM wireless shifting, an 800Wh battery, and a price tag roughly £1,000 higher. If those things matter to you — and they might — the 8 is worth the jump.

But the FS+ 4 is not a bike that will leave you wanting. The Bosch CX motor is identical across the FS+ range. The RockShox suspension does its job well for the intended use. The tubeless-ready Bontrager tyres at 2.4" are proper trail rubber. And the dropper post is fitted as standard, which means you're set up correctly from day one.

For riders in West Sussex and the wider South Downs area, this bike is well matched to local trails. The South Downs bridleway network rewards a bike with rear suspension — the chalk and flint loose-over-hard surfaces are exactly what the Deluxe Select shock handles confidently. You don't need 150mm of travel for these trails. You need something that keeps your rear wheel planted and your confidence high, and the FS+ 4 does both.

One note on weight: the FS+ 4 is not a light bike. At around 25–26kg fully built, it's heavier than a hardtail e-MTB by several kilos. That matters if you're lifting it onto a car rack, but on the trail — where the Bosch motor handles the climbing and the suspension handles the descending — it rarely registers. Most riders stop noticing the weight within a few rides.

If you're unsure whether the FS+ 4 or the hardtail range is right for your riding, the best thing to do is talk to us. That's what we're here for — and we'll give you a straight answer, not a sales pitch.