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.