FIT Series One v4 Complete Bike 20.5"

The Series One was FIT's first frame when the brand started back in 2000 – and it is still their most popular bike. For 2026 it gets a CNC-machined integrated head tube and a fully sealed front hub, and the lightened S1 frame and fork come in 3 top tube sizes with matching bar and crank sizes. This version has a 20.5" top tube.

Features

• 20.5" top tube
• CNC-machined integrated head tube with gyro holes
• Sealed front hub and sealed cassette rear hub
• Sealed Mid BB, FIT Key 25T sprocket

Specifications

• Top tube length: 20.5"
• Rear end length: 13.11"
• Head tube angle: 75.5°
• Seat tube angle: 71°
• BB height: 11.8"
• Standover height: 8.8"
• Frame: Chromoly top, seat and down tube
• Fork: Chromoly Steerer Tube, 33 mm Offset
• 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
• 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