Fairwheel Bikes’ Factor O2 Disc Project weighs just 5.1kg

Fairwheel claims to have made the world’s lightest road disc-brake race bike

US bike shop Fairwheel Bikes, which deals in high-end and exotic bikes, has put together what it claims to be the world’s lightest road disc-brake race bike — but says that building the world’s lightest bike was not its goal.


Total weight for the build comes in just under 5.1kg, though Fairwheel claims it could have brought that down by a further 328g to 4.76kg.

The aim of the project was to build “something that is very light, but still race worthy,” and it appears to have achieved that goal.

The build began with a Factor O2 Disc frame and fork, weighing 853.2g and 352.1g respectively. The drivetrain is based on SRAM Red eTap with minimal modifications, seeing only the pulleys on the rear derailleur replaced with lighter Extralite pulleys.

The rear derailleur was upgraded with Extralite pulleys
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As well as using ultralight components, a lot of thought went into saving weight elsewhere. For example, the headset is the stock CeramicSpeed lower bearing, for improved durability, but the upper has been replaced with a lighter Cane Creek AER bearing.

Similarly, the bottom bracket is fitted with full ceramic bearings and has the centre shield removed. Plus, the brake line isn’t routed past the crank spindle inside the frame, so isn’t at risk of being worn through which this saves a little extra weight too.

Thm Clavicula SE Cranks with some Carbon-ti and Fibrelyte chainrings
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The build also sees a plethora of exotic parts from the likes of Thm, Schmolke, Tune and Carbon-Ti. Standouts are the Thm Clavicula cranks and Tibia stem, Schmolke bars, and Carbon-Ti and Fibrelyte chainrings.

Custom wheels were built on Extalite SPD hubs, FSE prototype rims, Pillar titanium spokes and alloy nipples, delivering a wheelset that weighs just 820.4g.

From shaving off a few grams trimming brake lines, to replacing bolts with titanium versions, every detail has been considered on this build, and it can happily join the ranks of the esoteric and rarified builds Fairwheel has put together before.

A lightweight Ashima rotor is paired with some decadent rainbow Ti bolts
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Fairwheel Bikes lightweight bike build spec and weights

  • Frame: Factor 02 Disc, 853.2g
  • Fork: Factor 02 Disc, 352.1g
  • Headset: CeramicSpeed, Cane Creek AER, 52.8g
  • Stem: THM TIbia, 85.1g
  • Top cap/Expander: EE Cycleworks, 9.7g
  • Spacers: Tune Mg., 8.9g
  • Bars: Schmolke TLO, 146.4g
  • Bar tape: Lizard Skins DSP, 44.6g
  • Bar plugs: FWB Carbon, 5.4g
  • Saddle: Gelu, 46.4g
  • Seatpost: Schmolke, 78.3g
  • Seat collar: Factor integrated, 22.4g
  • Bottle cages: Carbone, 16.5g/pair
  • Shifters/brakes: SRAM e-Tap Hydraulic with calipers, 744.4g
  • Caliper bolts: Titanium, 9.9g
  • Front derailleur: SRAM e-Tap, 162.3g
  • Rear derailleur: SRAM e-Tap, Extralite pulleys, 224.2g
  • Cassette: Recon Al 11-25, 108.3g
  • Cranks: Thm Clavicula SE, 300.5g
  • Chainrings: Carbon-ti 50t, Fibre Lyte 34t, 104.4g
  • Chainring bolts: KCNC SL, 7.5g
  • Chain: YBN Titanium, 215.6g
  • Bottom bracket: HSC Full Ceramic, 68.6g
  • Rotors: Ashima Ai2, 144.3g
  • Rotor bolts: Titanium, 15g
  • Thru-axles: Factor, 57.5g/pair
  • Front hub: Extralite SPD, 64.9g
  • Rear hub: Extralite SPD, 145.4g
  • Rims: FSE Prototype, 442g/pair
  • Spokes: Pillar Xtra Titanium, 150.4g
  • Nipples: Pillar 13g, 17.7g
  • Tyres: Vittoria Corsa Speed, 377.2g/pair