Factor OSTRO VAM: TeXtreme, Biconvex Sections and the 15 mm Seatpost

Laminate and Curing: TeXtreme and Pitch-Based Fibre

Factor owns the factory that lays up its frames, and the OSTRO VAM is the clearest expression of what that ownership buys. A brand that outsources production inherits the curing schedule of its supplier: ramp rates, dwell times and the tooling that constrains them are chosen once and applied across every customer's layup. Factor sets its own. That latitude is what allows a frame to combine TeXtreme spread-tow sheets with Toray pitch-based fibre in the same structure without the laminate failing at the interface between them.

Spread tow is the less visible of the two materials. Conventional unidirectional tape carries a crimp where fibres cross, and every crimp is a small resin-rich pocket that adds mass and starts cracks. Spreading the tow into a wide, thin tape removes most of that crimp and lets plies overlap with a smaller step. Pitch-based carbon is the opposite kind of material: higher modulus than PAN fibre, more brittle, and used only where bending stiffness is worth the penalty in toughness.

The result is a frame quoted at 820 g painted in size 54. The second generation removed 250 g from the first, and the manufacturer attributes most of that to the layup rather than to the tube shapes. The ordering matters. Mass removed from the laminate is removed everywhere at once, while mass removed from a tube section is removed only where the section was changed.

Biconvex NACA Sections and the 15 mm Seatpost

The tube sections are NACA-derived, and the nose is biconvex rather than truncated. Most aero frames cut the trailing edge of the aerofoil flat and rely on the UCI's 3:1 rule to keep the section legal; the flat back is cheap to mould and behaves predictably at zero yaw. A biconvex nose is a different bet. It has no single stagnation point, so the flow can attach across a range of yaw angles instead of being pushed to one side of a sharp leading edge. The cost is depth: for the same drag at zero yaw, a biconvex section is deeper than a truncated one.

The seatpost follows the same reasoning at a smaller scale. It measures 15 mm across, a width the current UCI rules permit and the previous rules did not. A seatpost sits in the dirtiest air on the bicycle, downstream of the rider's legs, and a narrow post presents less surface to flow that is already turbulent. Making it that thin required moving the Di2 battery out of the post and into the seat tube, mounted from behind the bottom bracket. The change is as much about maintenance as about drag: battery access no longer requires removing the post, so saddle height cannot drift through repeated removal and refitting.

Bottle Cages, T47A and the Black Inc 48|58 Wheelset

Bottle cages are usually an afterthought and always a drag penalty. Factor designed two cages as part of the frame's aerodynamic package. The down tube cage guides air over the bottle rather than around it, and the seat tube cage reattaches flow to the seat tube behind it. The manufacturer's claim is specific: with the seat tube cage fitted and empty, the frame is faster than with no cage at all. Whether that survives independent testing is not the buyer's problem. The point is that the cages are supplied, shaped for those positions, and should not be replaced with generic hardware.

The bottom bracket is T47A, threaded, 86.5 mm wide. Threaded shells cost a little mass against press-fit and repay it in bearing alignment and serviceability: the cups seat square against machined threads, and a worn bearing is replaced without a press. CeramicSpeed bearings are fitted as standard in this build, which matters less for the friction figure than for the tolerance the cups are machined to.

The wheelset is Black Inc 48|58: 48 mm at the front, 58 mm at the rear, on the brand's own hubs. The depth differential keeps the front wheel manageable in a crosswind while the rear takes the deeper section where steering input is not a concern. Factor measures the complete second-generation bicycle at 7 W less drag than the first at 48 km/h on these wheels, a figure that belongs to the complete system rather than to the frame alone.

Mass, Fit and Acquisition

Mass for the reference build is 6.70 kg without pedals, in size 54, with Dura-Ace Di2 R9200. That is close enough to the UCI minimum of 6.8 kg that the choice of pedals, cages and computer mount decides whether the bicycle can be raced as delivered. A rider who intends to race should weigh the complete bicycle with their own contact points before assuming it is legal.

Tyre clearance is 32 mm, which is the current race standard rather than an endurance allowance. A 30 mm tyre on a 23 mm internal rim measures close to 32 mm once inflated, so the clearance is real but not generous. Riders who intend to run a nominal 32 mm should confirm the measured width on their rim before ordering.

Size 54 is the reference for the geometry quoted here, and the frame's stack and reach place it in the current race range rather than the endurance range. Riders between sizes should compare reach first: reach cannot be changed without altering the steering the frame was designed around, while stack can be adjusted with spacers within the manufacturer's limit.

At $11,899 or €11,600 the OSTRO VAM is the least expensive complete bicycle in this catalogue and the one with the narrowest margin between its natural build weight and the racing minimum. It is the correct choice for a rider who wants one bicycle for climbing and sprinting and is prepared to weigh it rather than assume it.