On paper, the Trek Powerfly+ FS 8 Gen 4 is a full-suspension eMTB with a Bosch Performance Line CX motor, an 800 Wh removable battery and wireless SRAM shifting. It’s listed at 54 lb. What it lacks for US riders is a price: Trek’s US Powerfly FS page describes the Gen 4 platform, but its Powerfly category page showed no FS 8 as of October 2026.
Here’s what is confirmed, what the parts mean on the trail, and what to ask a dealer.
What the FS 8 gets
| Part | Listed spec |
|---|---|
| Motor | Bosch Performance Line CX, assist to 20 mph |
| Battery | Bosch PowerTube 800 Wh, RIB 2.0 removable |
| Display | Bosch Kiox 300 |
| Travel | 130 mm front, 120 mm rear |
| Fork | Fox Rhythm 36, Float EVOL air spring, GRIP damper |
| Drivetrain | SRAM GX Eagle AXS T-Type, 12-speed, 10-52 cassette |
| Brakes | SRAM DB 8 4-piston hydraulic discs |
| Wheels and tires | 29-inch Bontrager Line Comp 30, tubeless-ready, Gunnison Pro XR 2.40-inch |
| Dropper | Bontrager Line, 170 mm |
| Frame | Alpha Platinum aluminum, Mino Link geometry adjustment, UDH, rack and fender mounts |
| Weight | 54 lb (24.48 kg) listed |
| Max total weight | 299.9 lb (136 kg), rider plus bike plus cargo |
| Sizes and colors (non-US retailer listing) | S, M, L, XL; Gloss Lava/Matte Dark Web or Matte/Gloss Mulsanne Blue |
Motor, battery and charging
Start with the motor. Trek says the Gen 4 CX ships at 85 Nm, and a Bosch firmware update (available from July 2025 onward) can raise it to 100 Nm. On the trail, that means more peak torque on steep, technical climbs, the ones where you’re crawling in a low gear. Who applies the update, and whether it costs anything, isn’t stated. Ask the dealer to confirm it’s applied before pickup.
The battery is the 800 Wh RIB 2.0, which comes out of the frame for charging indoors or travel. Trek says a full charge from empty takes about 7 hours, so plan an overnight top-up after a big day.
Want more range? The Bosch PowerMore extender works with the Gen 4 platform, but it needs a 100 mm reversed cable. It’s an easy detail to miss when you order.
The Bosch eBike Flow app handles assist tuning and ride logging, and syncs with Strava, komoot and Apple Health. Trek also lists over-the-air updates for the line.
The price question
Trek’s US Powerfly category page showed one Gen 4 model with a price: the Powerfly+ FS 4 Gen 4 in bluelight teal at $4,499.99. If you searched for what the Powerfly 4 Gen 4 costs, that’s the number. Prices as of October 2026.
Trek sells the FS 4 with a 600 Wh or an 800 Wh battery, so confirm which one that price covers. The FS 8 is a different bike with better parts, and I’d expect it to list above the FS 4. By how much is unknown.
Also unconfirmed: US arrival dates, which sizes and colors reach dealers, the rear shock model, and geometry numbers beyond the 66-degree head angle Trek quotes for the Gen 4 line. The parts list above comes from a UK Trek retailer, so a US build could differ. Bosch’s US page for the FS 8 confirms the 20 mph limit, the weight and the 29-inch wheels.
FS 8 against the FS 4 and the rest of the Gen 4 line
Both bikes share the same 130/120 mm travel. The differences are in the parts.
| Part | Powerfly FS+ 4 Gen 4 | Powerfly+ FS 8 Gen 4 |
|---|---|---|
| Battery | 600 Wh (800 Wh upgrade available) | 800 Wh |
| Fork | RockShox Recon Silver RL | Fox Rhythm 36 GRIP |
| Rear shock | RockShox Deluxe Select | Not listed |
| Drivetrain | Shimano CUES, 10-speed | SRAM GX Eagle AXS T-Type, 12-speed |
| Controller or display | Purion 200 | Kiox 300 |
| Brakes | Hydraulic discs | SRAM DB 8 4-piston |
Bosch’s US list also shows an FS 5 and an FS 6 Gen 4, both with 800 Wh. Neither spec sheet is in front of me, so compare them with the FS 8 once Trek posts US prices.
If you cross-shop another brand’s Bosch CX full-suspension bike, line up the same four things. Check rear travel against 120 mm, fork against the Fox 36-series, brake piston count and claimed weight against 54 lb. Those four numbers separate bikes that look alike on a spec sheet.
Where I land
The FS 8 looks like a sensible all-day trail bike. A 36-series fork and four-piston brakes suit a 54-lb bike better than the lighter parts on the FS 4. The AXS T-Type drivetrain also means no shift cable to stretch or snag.
It fits riders who want one bike for long mixed days: big climbs, flowing descents and the odd rack or fender for a commute. It’s a poor fit if you want a light bike, or more than 120 mm of rear travel. Trek’s own pitch for the FS 4 is rough roads and light singletrack, with no steep rock gardens or jump trails in the forecast. The FS 8 has the same travel and the same limit. For harder terrain, look at Trek’s Rail+ line, and our Rail+ 9.8 Gen 5 specs and US price status covers the nearest bigger option.
Two checks before you commit. A 299.9 lb total limit minus the 54-lb bike leaves roughly 245 lb for you and your gear. And the 20 mph assist limit matches the Class 1 pedal-assist rule, but many trail systems still ban e-bikes outright. Europe and Asia-Pacific bikes are limited to 25 km/h, so buy a US-market bike from a US dealer.
Right now, call a Trek dealer and ask for three things: the FS 8 out-the-door price with the battery size named, an expected arrival window for your frame size, and a spot on the waiting list. Ask them to confirm the 100 Nm update is applied, too.
Photo: Bicycle Art – La Digue – Seychelles by NorbertNagel, CC BY-SA 4.0, via Wikimedia Commons. Cropped.
