Fulcrum Speed 40C Rim Brake Wheelset

Carbon rim brake wheels at this level are a rarified proposition — and the Fulcrum Speed 40C Rim Brake Wheelset is built for the rider who knows exactly what they want. At 40mm deep, full carbon construction, and 1,420 grams for the pair, the Speed 40C delivers real aerodynamic performance without the handling compromises of deeper profiles. This is a wheel designed for road racing and fast riding, for the rider who is still on rim brakes by choice and wants a wheelset that reflects that conviction.

The rim is full carbon with Fulcrum's twill carbon fiber finish and a C17 internal width — 17mm across — optimized for 25 and 28mm tires. That wider channel allows the tire to sit in a rounder, more aerodynamically efficient profile, improving the aero performance of the wheel-and-tire system rather than just the rim in isolation. The external rim width of 24.2mm contributes to that tire shape as well. The braking surface carries Fulcrum's AC3 treatment — an aluminum-ceramic compound applied to the carbon surface that improves braking modulation and wet-weather stopping performance. For carbon rim brake wheels, the braking surface treatment is not a footnote; it is the difference between a wheelset that inspires confidence in variable conditions and one that does not. The AC3 surface meaningfully narrows the gap between carbon and aluminum in the rain.

The hubs are built around USB (Ultra Smooth Bearings) ceramic bearings in an adjustable cup-and-cone system. The front hub shell is carbon; the rear hub is aluminum with an oversized flange for lateral stiffness and efficient power transfer. Spoke count is 18 at the front — 9 per side — and 21 at the rear, built using Fulcrum's Two-to-One pattern: 14 drive-side spokes to 7 non-drive. This compensates for the lateral tension imbalance created by rear wheel dishing to accommodate the cassette. By doubling the drive-side spoke count, Fulcrum equalizes tension distribution between sides, stiffens the rear wheel under load, and reduces spoke fatigue over time. The spokes themselves are stainless steel, double-butted, aero profile, straight-pull. Available in Campagnolo and HG11 (Shimano/SRAM 11-speed) freehub compatibility.

Specs at a Glance

• Rim Depth: 40mm (front and rear)
• Rim Material: Full carbon, twill finish
• Rim Width: 24.2mm external / 17mm internal (C17)
• Braking Surface: AC3 aluminum-ceramic compound treatment
• Weight: 1,420g (pair)
• Front Hub: Carbon shell
• Rear Hub: Aluminum, oversize flange
• Bearings: USB ceramic, adjustable cup-and-cone
• Spoke Count: 18 front (9L / 9R) / 21 rear — Two-to-One (7L / 14R)
• Spokes: Stainless steel, double-butted, aero profile, straight pull
• Tire Type: Clincher
• Axle: Quick release
• Compatibility: Campagnolo or HG11 (Shimano / SRAM 11-speed)
• Color: Black

Design Benefits

1. AC3 braking surface. Fulcrum's aluminum-ceramic compound coating transforms the carbon braking track into a surface that performs consistently in wet and dry conditions. Carbon rim braking has a reputation for unpredictability in the rain; the AC3 treatment addresses this directly. Pair these with appropriate carbon-specific brake pads and the performance gap versus aluminum narrows considerably.
2. Two-to-One rear spoke pattern. The rear wheel carries 14 spokes on the drive side and 7 on the non-drive side. This compensates for the asymmetry of rear wheel geometry — cassette dishing forces the non-drive side to a shallower angle, which normally results in significantly lower spoke tension on that side. Doubling the drive-side count equalizes stress distribution, stiffens the rear wheel laterally, and reduces fatigue failure risk under sustained power output.
3. USB ceramic bearings. Ultra Smooth Bearings use ceramic balls that are harder, lighter, and smoother-rolling than steel. The adjustable cup-and-cone system allows precise preload tuning for bearing feel and longevity — an advantage over non-adjustable cartridge designs, particularly for riders who put high mileage on their wheels.
4. 40mm rim depth — the versatile aero choice. Deep enough to produce real aerodynamic benefit on open roads and for racing, shallow enough to remain manageable in crosswinds where 55 and 60mm profiles can push back. The 40mm profile is the wheelset depth you reach for across the widest range of conditions — from criteriums to gran fondos to windy coastal roads.
5. Full carbon rim construction. Carbon rims reduce rotating mass relative to aluminum, and rotating weight carries a greater performance penalty than static weight, particularly in acceleration and climbing. At 1,420g for a 40mm carbon clincher pair, the Speed 40C delivers a competitive weight target for a wheelset at this depth.
6. C17 internal rim width. The 17mm internal channel optimizes tire shape on 25 and 28mm tires — the tire spreads into a rounder, more aerodynamic profile that improves both rolling resistance and the aerodynamic system as a whole. Narrower internal widths pinch the tire into a more oval shape that works against both ride quality and aero efficiency.

Final Take

The Fulcrum Speed 40C Rim Brake Wheelset is for the serious road rider who is on rim brakes intentionally — on a high-end frame they have no plans to replace, or on a dedicated racing build where they want the weight, feel, and control that rim brakes deliver. At $2,413, you are paying for full carbon construction, Fulcrum's AC3 braking surface, USB ceramic bearings, and Two-to-One spoke architecture. These are not entry-level carbon wheels dressed in marketing language. They are a purpose-built performance wheelset for a rider who knows what they need — and is prepared to ride at the level these wheels demand.