GT Aggressor Expert 27.5" Mountain Bike - 2021

$569.73Compared to $760.00*
Reduced Price. You save 25%
*Intermediate markdowns may have been taken.
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Color: Silver
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Every day is a new adventure with the GT Aggressor Expert bike. The most off-road friendly hardtail from GT, it delivers the best in value, versatility and performance to recreational mountain bikers.

  • Features

    • Locking SR Suntour XCM-DS 80 mm front fork transitions smoothly from pavement to trail, absorbing bumps on the driveway or dirt
    • 24-speed drivetrain ensures a perfect gear for any grade
    • With a slight-rise handlebar and paddle saddle, rolling into the world of mountain biking feels natural and comfortable
    • 27.5 x 2.25 in. WTB Ranger Comp tires
    • Hydraulic disc brakes with 160/160 mm rotors
    • Closeout
    • Specs and images are subject to change


    This bike comes with Coast to Coast Support, which includes:
    • 1 year of free adjustments (see more below)
    • In-store bike assembly
    • Pickup in store or curbside
    • Bike experts available at 170+ bike shops
    REI Co-op Members get more:
    • Free flat tire repairs (labor only; parts not included)
    • 20% off shop services
    More about our free adjustments:
    New bikes go through a normal break-in period, after which they should be readjusted. All bicycles sold at REI include free adjustments for one year after purchase date—as many times as you need. Included: derailleur and brake adjustments, lateral wheel truing, hub and headset bearing adjustments, tire inflation and chain lubrication. Not included: replacement or installation of new components or accessories, any other services. Call your local REI Co-op Bike Shop for more information.

    View all GT Hardtail Mountain Bikes
  • Technical Specs

    Best Use

    Mountain Biking

    Mountain Bike Style



    6061 T6 aluminum, triple triangle with floating seatstays; forged drop-outs with disc brake mounts; zero stack 1-1/8" head tube

    Bike Suspension

    Front Suspension


    SR Suntour XCM-DS, 80 mm, hydraulic lockout and preload, coil

    Fork Travel

    80 millimeters


    Shimano TY301, 42/34/24T

    Bottom Bracket

    Cartridge, square taper


    Shimano SL-M315, 8-speed

    Front Derailleur

    Shimano TY600

    Rear Derailleur

    Shimano Tourney

    Rear Cogs

    12-32T, 8-speed

    Number of Gears

    24 gear(s)

    Brake Type

    Hydraulic Disc Brake


    Tektro M275 hydraulic disc, 160/160 mm rotors

    Brake Levers

    Tektro M275 hydraulic disc


    WTB SX19, 32h

    Front Hub

    Alloy disc, QR

    Rear Hub

    Alloy disc cassette QR, 28h

    Wheel Size

    27.5 inches


    WTB Ranger Comp, 27.5 x 2.25, DNA compound

    Tire Width

    2.25 inches

    Handlebar Shape

    Riser Bar


    GT All Terra alloy riser, 25 mm rise, 8 deg. sweep, 6 deg. rise, 720 mm width


    GT All Terra, 6061 alloy, 31.8, 8 deg.

    Seat Post

    GT All Terra 2-bolt alloy


    GT MTB


    GT Slim Line flat


    Semi-integrated, sealed cartridge


    KMC Z8.3, 8-speed


    30 lbs. 14.4 oz.

    Bike Weight

    Bike weight is based on median size, as sold, or the average of two median sizes.



  • Size Chart

    Effective Top Tube53.254.956.9
    Seat Tube Center-Top384246
    Standover Height70.773.275.7
    Head Tube Length111213
    Head Tube Angle (degrees)686868
    Seat Tube Angle (degrees)73.573.573.5
    Bottom Bracket Height31.531.531.5
    Fork Offset4.24.24.2

    Sizing Notes

    Measurements are stated in centimeters unless otherwise indicated.

    How we measure bikes

    1. Standover Height Standover Height is a measurement from the ground to the top of the top tube, measured at the midpoint of the top tube.
    2. Reach Reach is the horizontal distance from the center of the cranks to the center of the head tube, measured at head tube level.
    3. Stack Stack is the vertical distance from the center of the cranks to the center of the head tube, measured to the top of the head tube.
    4. Effective Top Tube Effective top tube is the distance from the center of the head tube to the center of the seat tube/seat post, measured parallel to the ground.
    5. Seat Tube Center to Top Seat Tube length is the measurement of the seat tube, from the center of the cranks to the top of the seat tube.
    6. Head Tube Length Head Tube Length is measured from the bottom to the top of the head tube.
    7. Head Tube Angle Head Tube Angle is the acute angle between the head tube and the ground (measured towards the rear of the bike)
    8. Seat Tube Angle Seat Tube Angle is the acute angle between the seat tube and the ground (measured towards the rear of the bike).
    9. Bottom Bracket Height Bottom Bracket Height is a measurement taken vertically from the ground up to the center of the cranks.
    10. Wheelbase Wheelbase is the measurement from the center of the front axle to the center of the rear axle.
    11. Chainstay Length Chainstay Length is the measurement from the center of the cranks to the center of the rear axle.
    12. Fork Offset Fork Offset, or rake, is the distance from the front axle to a line drawn parallel to the center of the head tube or steering axis.
  • Reviews
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