Carbon Fiber Sporting Goods
Bola 27.5" Carbon Downhill MTB Rim – 40mm Outer, 32mm Inner, 30mm High
Bola 27.5" Carbon Downhill MTB Rim – 40mm Outer, 32mm Inner, 30mm High
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Engineered for modern downhill MTB, the Bola 27.5" carbon rim features a robust 40mm outer width and 32mm inner width for superior tire support and stability on aggressive descents. Weighing 560g, its 30mm height and T700/T800 carbon layup optimize impact resistance while maintaining precise handling, tailored for riders and builders demanding durability, lightweight construction, and competitive performance.
Product Features
- Rim Size: 27.5" (650B, ISO 584mm)
- Widths: 40mm outer / 32mm inner (hookless, tubeless-ready)
- Height: 30mm profile for lateral stiffness
- Material: UD T700/T800 carbon fiber, epoxy resin
- Spoke Count: 28H (J-bend/straight-pull compatible)
- Weight: 560g ±5%
- Valve: Presta (6.5mm valve hole, customizable)
- Recommended Tires: 2.0–2.6" MTB, optimized for 2.3–2.5"
- Max Rider Weight: 120kg
Why 32mm Inner Width?
- Maximizes cornering grip & reduces pinch-flat risk with wide MTB tires
- Supports lower tire pressures for aggressive downhill runs
- Meets ETRTO, ISO, and UCI rim/tire compatibility standards
Specification Table
| Parameter | Value |
|---|---|
| Rim Diameter | 27.5" / 650B (ISO 584mm) |
| Outer Width | 40mm |
| Inner Width | 32mm |
| Profile Height | 30mm |
| Spoke Count | 28H |
| ERD | 540mm |
| Valve Hole | 6.5mm (Presta, customizable) |
| Tubeless Ready | Yes (hookless profile) |
| Weight | 560g ±5% |
Test Certifications & Tolerances
- Impact and fatigue tested per ISO 4210-7
- Forward compressive strength: >300kg
- Spoke hole tension: >280kg
- Lateral torsion: >50kg
- Dynamic balance: <3g
- Flatness tolerance: <0.15mm
Comparison: 27.5" vs 29" Carbon DH Rims
| Feature | Bola 27.5" DH | Typical 29" DH |
|---|---|---|
| Rim Diameter | 27.5" | 29" |
| Outer/Inner Width | 40/32mm | 31/30mm |
| Weight | 560g | 590–650g |
| Agility | Better cornering, faster turns | Smoother rollover, higher momentum |
| Rider Height Suitability | Shorter/medium | Medium/taller |
Frequently Asked Questions
Is a 27.5 inch carbon MTB rim with 40mm outer width good for downhill riding?
Yes, the 40mm outer/32mm inner rim is ideal for downhill as it allows for stable tire profiles, increased traction, and improved impact resistance for aggressive terrain.
What's the advantage of a 32mm inner width rim for mountain bike downhill setups?
A 32mm inner width provides wider tire bead seating, allowing use of modern 2.4–2.6" tires at lower pressures, which increases cornering grip and reduces puncture risk.
How does a 27.5er carbon DH rim compare to a 29er rim for aggressive trails?
27.5" rims offer quicker handling and increased playfulness, while 29" rims excel at rolling over obstacles. Your choice depends on terrain and rider style.
Are tubeless-ready carbon rims worth it for downhill mountain biking?
Tubeless-ready carbon rims allow lower tire pressures and reduce flats, benefiting traction and comfort in aggressive downhill. Ensure rim tape is installed properly for airtightness.
What rim depth and width should I look for in a downhill mountain bike wheel?
Look for inner width of 30–32mm and rim height of 25–32mm for optimal tire support and lateral stiffness when riding technical and steep trails.
