The Trek 3900 is the top model in Trek's 3 Series of hardtail mountain bikes which are designed for beginners looking to hit the local park or take the long way home. The Trek 3900 has a 100mm suspension fork for comfort and durability for years to come. It also features a full Shimano 8-speed drivetrain and uses various other parts from Bontrager, such as the seat, handle bars and 26 x 2.0" tires. It has a redesigned Alpha White Aluminum frame with semi-integrated head tube, bi-oval down tube with integrated gusset, rack and fender mounts, disc compatible dropouts, replaceable derailleur hanger and is available in sizes from 13" to 22.5" in a Matte Black or Matte Orange finish. The Trek 3900 comes with the option of rim brakes or with more powerful disc brakes as the Trek 3900 Disc.
- Sizes: 13, 16, 18, 19.5, 21, 22.5"
- Frame: Alpha White Aluminum w/semi-integrated head tube, bi-oval down tube w/integrated gusset, rack and fender mounts, disc compatible dropouts, replaceable derailleur hanger
- Front: Suspension SR Suntour SF9 XCT V2 w/coil spring, preload, 100mm
- Trek 3900: Formula Alloy FM31 hubs; Bontrager 550 rims w/brushed
- Trek 3900 Disc: Formula Alloy DC20 front hub, FH-M475 rear hub; Bontrager 550 rims w/brushed sidewalls
- Tires: Bontrager LT-3, 26x2.0"
- Shifters: Shimano EF50, 8 speed
- Front Derailleur: Shimano C051
- Rear Derailleur: Shimano M360
- Crank: Shimano M191, 42/34/24
- Cassette: SRAM PG830 11-32, 8 speed
- Pedals: Wellgo nylon platform
- Saddle: Bontrager SSR
- Seat Post: Bontrager SSR, 31.6mm, 20mm offset
- Handlebars: Bontrager Approved Riser, 30mm rise
- Stem: Bontrager Approved, 25 degree
- Headset: VP-A68-TK, 1-1/8" semi-cartridge, sealed
- Trek 3900: Tektro V w/Shimano EF50 levers
- Trek 3900 Disc: Promax, mechanical disc w/Shimano EF50 levers