Carbon Fiber Sporting Goods
Ultralight Carbon Gravel Bike Rims 700c | 34mm Wide, U-Shape, 35mm & 40mm | Disc Brake | Bola
Ultralight Carbon Gravel Bike Rims 700c | 34mm Wide, U-Shape, 35mm & 40mm | Disc Brake | Bola
Couldn't load pickup availability
Ultralight Carbon Gravel Bike Rims — 700c, 34mm Wide, Disc Brake (Bola)
Bola's 700c carbon gravel rims deliver verified disc-brake performance in three weight classes — Normal (460g), Superlight (410g), and Ultralight (360g per rim) — with a 34mm outer / 25mm inner U-shape profile optimised for tubeless gravel tyre compatibility from 28c to 50c. Available in 35mm and 40mm heights to suit either all-day endurance riding or aerodynamic efficiency.
Who These Rims Are Designed For
- Competitive gravel and cyclocross teams requiring sub-400g disc-specific rims without sacrificing structural integrity
- Small and medium cycling brands seeking OEM/white-label rims with consistent, verifiable quality (three-year warranty)
- Endurance cyclists running wide tubeless setups who need a 25mm inner width for reduced rolling resistance and improved tyre volume
Rim Profile Options: 35mm vs. 40mm
| Specification | 35mm Height | 40mm Height |
|---|---|---|
| Primary Use Case | Technical gravel, endurance, rough terrain | Mixed-surface racing, aerodynamic efficiency |
| Outer Width | 34mm | 34mm |
| Inner Width | 25mm | 25mm |
| ERD | 539mm | 539mm |
| Max Tyre Pressure | 125 psi | 125 psi |
| Valve Hole Dia. | 6.5mm (customisable) | 6.5mm (customisable) |
Full Technical Specifications
- Rim Shape: U-shape (wider internal channel vs. V-shape; optimised for gravel tyre profiles)
- Outer Width: 34mm (variant: 31mm available)
- Inner Width: 25mm (tubeless-ready)
- Weight per Rim: Normal 460±15g | Superlight 410±10g | Ultralight 360±10g
- Forward Compressive Strength: >300kg
- Lateral Torsion: >50kg
- Spoke Hole Tension: >280kg
- Dynamic Equilibrium: <3g imbalance
- Flatness Tolerance: <0.15mm
- Roundness Tolerance: <0.3mm
- Assembly Hole Diameter: 7.5mm (customisable)
- Spoke Hole Diameter: 4.5mm (customisable)
- Nipple Direction: Front 7°, Rear 5° & 7° (customisable)
- Tyre Pressure Range: 100–125 psi
- Max Rider Weight: 120kg
- Brake Compatibility: Disc brake only
Why U-Shape Over V-Shape for Gravel?
The U-shape profile maintains a consistent internal channel width of 25mm across the full bead-seat area. Compared to a V-shape rim of equivalent height, the U-profile reduces tyre deformation under cornering loads and supports a broader tyre volume range (typically 32c–50c), which is critical for mixed-surface gravel riding. V-shape rims of similar height typically offer 2–4mm narrower internal widths, increasing tyre sidewall tension and limiting tubeless bead retention reliability on rough terrain.
Weight Class Comparison
| Weight Class | Weight per Rim | Recommended Use |
|---|---|---|
| Normal | 460±15g | Training, endurance, heavier build tolerance |
| Superlight | 410±10g | Race-day gravel, cyclocross |
| Ultralight | 360±10g | Competitive racing, weight-optimised builds (<120kg rider) |
Note: The 50g reduction from Normal to Ultralight (per rim) translates to 100g savings across a paired wheelset. Ultralight rims are recommended for riders under 100kg on non-technical terrain to maintain the rated structural tolerances above.
Customisation & OEM Services
All hole diameters (assembly, valve, spoke) are available in custom dimensions. Nipple angle, drilling pattern, and branding options are offered for cycling brands and professional teams. Minimum order quantities and lead times are available on request. Three-year warranty included on all production runs.
Frequently Asked Questions
- Q: Are these rims tubeless-compatible?
- A: Yes. The 25mm inner width and U-shape profile are engineered for tubeless tyre fitment. A tubeless-ready rim tape and valve are required and sold separately.
- Q: Should I choose 35mm or 40mm height for gravel riding?
- A: 35mm is recommended for technical or mixed-surface gravel where vertical compliance and handling agility are priorities. The 40mm profile provides measurable aerodynamic advantage on faster, smoother gravel or mixed-road segments, with minimal additional weight penalty at this rim width.
- Q: What is the weight difference between Superlight and Ultralight versions?
- A: The Superlight weighs 410±10g per rim; the Ultralight weighs 360±10g per rim — a nominal 50g difference per rim, or approximately 100g for a full wheelset build.
- Q: What tyre widths are compatible with the 25mm inner width?
- A: A 25mm inner width is compatible with tyres from approximately 28c to 50c. ETRTO guidelines recommend a minimum tyre width of 28mm for a 25mm internal rim width to maintain safe bead retention.
- Q: Can these rims be used with rim brake systems?
- A: No. These rims are designed exclusively for disc brake drivetrains. There is no braking surface machined into the rim sidewall.
