Powerfly FS 4 | Trek Bikes

You want to get out and explore more trails. You're looking for an e-MTB with trail-smoothing full suspension and the reliable, leg-boosting power of an electric drive system made specifically for the demands of off-road riding.

A durable aluminum frame that fully encases a long-range 500Wh battery, a powerful Bosch Performance CX (250Wh, 85 Nm) motor that helps you sustain speeds of up to 20 mph or 32 km/h, and an ergonomic Purion controller. Plus, a 120mm suspension fork, 100mm of rear travel, a 10-speed Shimano drivetrain, and a dropper post.

This full suspension e-MTB is comfortable, efficient, and fast on rough terrain. The powerful Bosch electric drive system makes it possible to tackle any climb you encounter and adventure farther than ever.

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
Trek's 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 it's 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 you'll get the fastest wheel that fits—29˝ wheels on larger frames, 27.5˝ wheels on smaller frames

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.

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.

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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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.

Calculate your range

This suspension calculator will help you optimize your suspension settings for your riding weight. Simply follow the steps to find your best set up.

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Bosch's Purion display features a fully-functional speedometer with a backlit display, service interval indicator, and battery range indicator. Its thoughtful design allows riders to scroll through functions or choose the right level of support while maintaining contact with handlebars.

The right wheel size paired with your frame size gives you the perfect combination of responsiveness and control.

Use the remote lever to lower your saddle so it's out of your way when you're descending and cornering.

You've got one less detail to sweat with the integrated speed sensor. The chainstay-mounted sensor stays protected while the custom hub-mounted magnet stays secure—no more error codes from mis-aligned sensors.

The bike is already internally wired to accept additional lights. Go to your dealer and simply have them attached to the bike and plug them in.

*spec applies to all sizes unless otherwise noted

Frameset

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	Size: XS , S 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
*Fork	Size: M , L , XL SR Suntour XCR 34, air spring, LO R damper, hydraulic lockout, tapered steerer, 44mm offset, oversized crown for eMTB, Boost110, 15mm bolt-on thru axle, 120mm travel
Shock	SR Suntour Edge R, 190mm x 45mm

Wheels

Hub front	Bontrager sealed bearing, alloy axle, 6-bolt, Boost110, 15mm thru axle
Hub rear	Bontrager alloy, sealed bearing, alloy axle, 6-bolt, Shimano 8/9/10 freehub, Boost148, 12mm thru axle
Skewer rear	Bontrager Switch thru axle, removable lever
Rim	Alex MD35, Tubeless Ready, 32-hole, 35mm width, presta valve
Spokes	14g stainless steel
*Tire	Size: XS , S Bontrager XR3 Comp, wire bead, 30tpi, 27.5x2.35''
*Tire	Size: M , L , XL Bontrager XR3 Comp, wire bead, 30tpi, 29x2.30''
Rim strip	Bontrager TLR

Drivetrain

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
Pedal	VP-536 nylon platform

Components

Saddle	Bontrager Arvada, steel rails, 138mm width
*Seatpost	Size: XS , S , M TranzX JD-YSP18, 100mm travel, internal routing, 31.6mm, 361mm length
*Seatpost	Size: L , XL TranzX JD-YSP18, 130mm travel, internal routing, 31.6mm, 425mm length
Handlebar	Bontrager alloy, 31.8mm, 15mm rise, 720mm width
Grips	Bontrager XR Trail Comp, nylon lock-on
*Stem	Size: XS , S Bontrager alloy, 31.8mm, Blendr compatible, 7 degree, 60mm length
*Stem	Size: M , L , XL Bontrager alloy, 31.8mm, Blendr compatible, 7 degree, 70mm length
Brake	Tektro HD-M275 hydraulic disc
Brake rotor	Tektro, 6-bolt, 203mm

Accessories

Battery	Bosch PowerTube 500
Charger	Bosch compact 2A (100-240V) charger
Controller	Bosch Purion
Motor	Bosch Performance CX, magnesium motor body, 250 watt, 85 Nm, 20mph or 32km/h max assist

Weight

Weight	M - 24.89 kg / 54.88 lbs (with tubes)
Weight limit	This bike has a maximum total weight limit (combined weight of bicycle, rider, and cargo) of 300 pounds (136 kg).

We reserve the right to make changes to the product information contained on this site at any time without notice, including with respect to equipment, specifications, models, colors, and materials.

Bike and frame weights are based off pre-production painted frames at time of publication. Weights may vary in final production.

The charts below show our recommended sizes based on height, but there are some other factors, like arm and leg length, that determine a great fit. That’s why you’ll see some overlap in our recommendations. Not every rider who’s 5´8˝, for example, will fit on the same size bike. The best way to find your perfect fit is to consult the experts at your local retailer.

Rider Height

Inseam

137.0 - 155.0 cm

4'5.9" - 5'1.0"

64.0 - 73.0 cm

25.2" - 28.7"

153.0 - 166.5 cm

5'0.2" - 5'5.6"

72.0 - 79.0 cm

28.3" - 31.1"

161.0 - 175.0 cm

5'3.4" - 5'8.9"

76.0 - 82.0 cm

29.9" - 32.3"

174.0 - 188.0 cm

5'8.5" - 6'2.0"

82.0 - 88.0 cm

32.3" - 34.6"

186.0 - 196.0 cm

6'1.2" - 6'5.2"

87.0 - 92.0 cm

34.3" - 36.2"

All measurements provided in cm unless otherwise noted.

Frame size number	Frame size letter	Wheel size	A — Seat tube	B — Seat tube angle	Effective seat tube angle	C — Head tube length	D — Head angle	E — Effective top tube	F — Bottom bracket height	G — Bottom bracket drop	H — Chainstay length	I — Offset	J — Trail	K — Wheelbase	L — Standover	M — Frame reach	N — Frame stack
14.5	XS	27.5"	36.8	68.3°	76.0°	14.0	66.5°	55.4	33.2	2.4	46.8	4.4	10.7	117.0	69.1	40.5	59.9
15.5	S	27.5"	39.5	68.3°	76.0°	14.0	66.5°	56.4	33.2	2.4	46.8	4.4	10.7	118.0	69.1	41.5	59.9
17.5	M	29"	42.0	67.5°	76.0°	13.0	66.5°	58.9	33.5	3.9	47.0	4.4	11.4	120.6	71.2	43.0	63.7
19.5	L	29"	45.0	67.5°	76.0°	14.0	66.5°	62.1	33.5	3.9	47.0	4.4	11.4	124.0	71.6	46.0	64.6
21.5	XL	29"	50.0	67.5°	76.0°	14.0	66.5°	64.6	33.5	3.9	47.0	4.4	11.4	126.5	71.3	48.5	64.6

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Features

Suspension Calculator

Learn more

Bosch Purion Display

Smart Wheel Size

Dropper post

Integrated speed sensor

Lighting ready

Specifications

Sizing & fit