The Series One was our first frame when we started FIT back in 2000 and it’s our most popular bike to date. For 2026 we’ve upgraded to a CNC machined Integrated headtube and a fully sealed bearing front hub. The S1 frame and fork has been lightened up and offered in 3 top tube sizes with corresponding handlebar and crank sizes.
Geometry
Top Tube Length: 20.25"
Rear End Length: 13.11"
Head Tube Angle: 75.5°
Seat Tube Angle: 71°
BB Height: 11.8"
Standover: 8.8"
Frame: Chromoly top, seat and down tube
Fork: Chromoly Steerer Tube, 33 mm Offset
Bar: 8.7" rise, 29" width, 2-piece
Stem: FIT Forged Top Load, 50 mm reach
Headset: Integrated with Gyro Holes
Brake Mounts: Welded
Rear Brake: U-Brake with Low Tension Springs
Brake Lever: 2-finger
Brake Cable: Linear
Gearing: 25/9 RHD
Cranks: Tubular Chromoly, 160 mm length, RHD
Bottom Bracket: Mid, sealed bearing
Sprocket: Fit Key 25T
Pedals: Fit PC
Front Hub: sealed, 10 mm axle
Rear Hub: Cassette, sealed bearings, 14 mm axle, RHD, 17 mm nuts
Rims: FIT S1W, 36H, single wall, alloy
Tires: FIT OEM 20" x 2.4"
Seat: Seat/Post Combo
Seat Post: 200mm Seat/Post Combo, 25.4 mm diameter
Seat Clamp: alloy, 28.6 mm inner diameter
Weight: 12 kg
