Powerfly FS 4 is a full suspension electric mountain bike built to tackle rugged trail adventures. The plush suspension setup soaks up rough terrain, and the powerful Bosch electric drive system boosts your capacity to crush climbs and mile after mile of singletrack.
- For e-MTB, full suspension is a game-changer: it soaks up rugged terrain so you can ride the Bosch pedal-assist system to its full potential
- Treks Removable Integrated Battery (RIB) system looks great and is super user-friendly: it fully hides the battery in the frame for protection, makes it easy to remove the battery without tools, and lets you mount a water bottle cage—even on full suspension e-MTBs
- The dropper post lets you lower your saddle on the fly so its out of the way on descents
- The Purion controller has Walk Assist and an intelligent eMTB mode that automatically delivers the right amount of power based on your terrain
- Powerfly FS frames feature a curved top tube that makes standing over the bike easier. Plus, Smart Wheel Sizing means youll get the fastest wheel that fits—29˝ wheels on larger frames, 27.5˝ wheels on smaller frames
Bosch Performance Line CX motor
Bosch Performance Line CX sets the standard for eMTB performance with up to 85Nm of torque and an intelligent eMTB mode with Extended Boost that automatically adjusts the amount of assist based on the terrain.
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Custom eMTB Lite mode
Trek eMTBs feature a custom eMTB Lite mode in place of Tour mode. It gives you more natural-feeling power delivery and longer battery life.
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Removable Integrated Battery
RIB is a one-piece battery and cover with a built-in handle that can easily be removed and re-installed in the frame with no tools and no hassle. It’s the most convenient way to remove your battery for transport, security, or just easier charging.
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What is the range?
To see how far you can ride your electric mountain bike on a single charge, check out Bosch’s range calculator. We’ve auto-filled the variables for this bike model and the average rider, but you can make adjustments to get your most accurate estimate.
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Compliant with leading safety regulations
The e-systems on Trek and Electra e-bikes are third-party tested to meet the latest e-bike safety regulations, including the stringent UL 2849 certification — so all you have to worry about is where your e-bike will take you next.
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Frame |
Alpha Platinum Aluminum, Removable Integrated Battery (RIB), tapered head tube, internal routing, Motor Armor, magnesium rocker link, rack and fender mount, ABP, Boost148, 100mm travel |
Fork |
SR Suntour XCR 34, air spring, LO R damper, hydraulic lockout, tapered steerer, 41mm offset, oversized crown for eMTB, Boost110, 15mm bolt-on thru axle, 100mm travel |
Shock |
SR Suntour Edge R, 190mm x 45mm |
Tire |
Bontrager XR3 Comp, wire bead, 30tpi, 27.5x2.35 |
Hub Front |
Bontrager sealed bearing, alloy axle, 6-bolt, Boost110, 15mm thru axle |
Hub Rear |
Bontrager Approved DC-3248, sealed bearing, alloy axle, 6-bolt, Shimano 8/9/10 freehub, Boost148, 12mm thru axle |
Rim |
Alex MD35, tubeless compatible, 32-hole, 35mm width, Presta valve |
Rim Strip |
Bontrager TLR |
Spokes |
14g stainless steel, black |
Skewer Rear |
Bontrager Switch thru axle, removable lever |
Shifter |
Shimano Deore M4100, 10 speed |
Rear Derailleur |
Shimano Deore M5120, long cage |
Crank |
FSA Bosch CK-220, 36T ring, 165mm length |
Cassette |
Shimano Deore M4100, 11-46, 10 speed |
Chain |
KMC X10, 10 speed |
Chainring |
FSA, 36T, steel |
Brake Rotor |
Tektro, 6-bolt, 203mm |
Pedal |
VP-536 nylon platform |
Saddle |
Bontrager Arvada, steel rails, 138mm width |
Seatpost |
TranzX JD-YSP18, 100mm travel, internal routing, 31.6mm, 361mm length |
Seat Collar |
Bolt-on, 36.4mm |
Handlebar |
Bontrager alloy, 31.8mm, 15mm rise, 720mm width |
Stem |
Bontrager Comp, 31.8mm, Blendr compatible, 7 degree, 60mm length |
Headset |
FSA IS-2 |
Grips |
Bontrager XR Trail Comp, nylon lock-on |
Fender |
Trek Powerfly 29 custom fender |
Battery |
Bosch PowerTube 500Wh |
Motor |
Bosch Performance CX, magnesium motor body, 250 watt, 85 Nm, 20mph or 32km/h max assist |
Charger |
Bosch compact 2A, 100-240V |
Geometry Chart
B B Drop |
2.4 |
B B Height |
33.2 |
Chainstay Length |
46.8 |
Eff Seat Tube Angle |
76.0° |
Eff Top Tube |
55.4 |
Frame Reach |
40.5 |
Frame Size Letter |
XS |
Frame Size Number |
14.5 |
Frame Stack |
59.9 |
Head Angle |
66.5° |
Head Tube Length |
14 |
Offset |
4.4 |
Seat Tube |
36.8 |
Seat Tube Angle |
68.3° |
Standover |
69.1 |
Trail |
10.7 |
Wheelbase |
117 |
Wheel Size |
27.5" |
B B Drop |
2.4 |
B B Height |
33.2 |
Chainstay Length |
46.8 |
Eff Seat Tube Angle |
76.0° |
Eff Top Tube |
56.4 |
Frame Reach |
41.5 |
Frame Size Letter |
S |
Frame Size Number |
15.5 |
Frame Stack |
59.9 |
Head Angle |
66.5° |
Head Tube Length |
14 |
Offset |
4.4 |
Seat Tube |
39.5 |
Seat Tube Angle |
68.3° |
Standover |
69.1 |
Trail |
10.7 |
Wheelbase |
118 |
Wheel Size |
27.5" |
B B Drop |
3.9 |
B B Height |
33.5 |
Chainstay Length |
47 |
Eff Seat Tube Angle |
76.0° |
Eff Top Tube |
58.9 |
Frame Reach |
43 |
Frame Size Letter |
M |
Frame Size Number |
17.5 |
Frame Stack |
63.7 |
Head Angle |
66.5° |
Head Tube Length |
13 |
Offset |
4.4 |
Seat Tube |
42 |
Seat Tube Angle |
67.5° |
Standover |
71.2 |
Trail |
11.4 |
Wheelbase |
120.6 |
Wheel Size |
29" |
B B Drop |
3.9 |
B B Height |
33.5 |
Chainstay Length |
47 |
Eff Seat Tube Angle |
76.0° |
Eff Top Tube |
62.1 |
Frame Reach |
46 |
Frame Size Letter |
L |
Frame Size Number |
19.5 |
Frame Stack |
64.6 |
Head Angle |
66.5° |
Head Tube Length |
14 |
Offset |
4.4 |
Seat Tube |
45 |
Seat Tube Angle |
67.5° |
Standover |
71.6 |
Trail |
11.4 |
Wheelbase |
124 |
Wheel Size |
29" |
B B Drop |
3.9 |
B B Height |
33.5 |
Chainstay Length |
47 |
Eff Seat Tube Angle |
76.0° |
Eff Top Tube |
64.6 |
Frame Reach |
48.5 |
Frame Size Letter |
XL |
Frame Size Number |
21.5 |
Frame Stack |
64.6 |
Head Angle |
66.5° |
Head Tube Length |
14 |
Offset |
4.4 |
Seat Tube |
50 |
Seat Tube Angle |
67.5° |
Standover |
71.3 |
Trail |
11.4 |
Wheelbase |
126.5 |
Wheel Size |
29" |