This carbon fiber mountain bike rim is built for all-mountain use, featuring a 25mm height, 33mm outer width, and straight-side design—optimized for tubeless setups and easy tire handling. Crafted with lightweight yet durable carbon fiber, it balances agility and strength, fitting 2.2-2.45" tires for stability across trails, enduro, and XC rides. Backed by 10 years of manufacturing experience, our factory offers customizations to meet specific needs, ensuring tailored performance for every rider.

Product Features and Advantages

Rim Design:

25mm Height + 33mm Outer Width

The 25mm height ensures longitudinal rigidity while reducing rotational inertia, enhancing climbing efficiency and steering responsiveness. With a 33mm outer width, it perfectly accommodates 2.2-2.6 inch mountain bike tires, boosting sidewall support to minimize cornering deformation. This translates to over 20% better grip on muddy, gravelly, or technical terrain, and exceptional stability during high-speed descents.

Straight-Side Design:

Optimized for tubeless setups, it achieves superior airtightness without the need for extra sealing tape, eliminating the risk of air leakage common in traditional rims. The flattened edge design speeds up tire installation and removal by 50%, making on-trail repairs quicker and easier.

Reinforced Spoke Hole Construction:

Features embedded spoke holes paired with high-strength aluminum spoke nipples. This design distributes spoke tension evenly, reducing localized stress on the rim and lowering the risk of loose spokes or rim cracks—significantly enhancing overall wheel durability.

Carbon Fiber Material:

Weighs over 35% less than equivalent aluminum rims, reducing rider fatigue and improving acceleration and climbing efficiency. Crafted from high-modulus carbon fiber composite, it exceeds EN 14766 mountain bike standards, with impact and fatigue resistance far surpassing metal—easily handling repeated hits from rocks, roots, and rough terrain.Carbon fiber’s natural vibration-damping properties filter out small road imperfections, increasing comfort during long rides. Meanwhile, its exceptional rigidity ensures instant power transfer, delivering precise handling during cornering and sprints.

Customization and Reliability：

Backed by 10 years of carbon fiber rim manufacturing expertise, we offer customizations such as spoke count and color options to match different frames and riding styles. Every rim undergoes rigorous pressure testing and real-world ride validation, guaranteeing durability and safety across all mountain scenarios.

Strict Quality Control:

KOBIKE do 100% tire pressure(150 PSI), flatness(＜0.2mm) and roundness(＜0.2mm) inspections before shipping, also offering 2 years warranty for our carbon rims.

Product Structure

Rim Well:

A narrow, deep-groove design with an integrated rubber sealing layer creates an airtight channel for 2.2-2.45" tubeless tires. No extra tape needed, solving common air leakage issues.

Rim Flange:

Straight-side (no hooks) with a flush, reinforced edge—15% thicker than aluminum equivalents. Eases tire installation/removal while ensuring a secure grip on high-pressure tubeless beads, preventing slippage.

Rim Wall:

25mm depth balances low wind resistance and rigidity. Crafted from UD carbon with 3 internal reinforcement ribs, it weighs ~450g per rim while boosting longitudinal stiffness by 30% for downhill stability. Matte finish adds UV and scratch resistance.

Valve Hole：

Standard Presta (6mm diameter) with 12mm offset to avoid spokes. Fitted with a high-elasticity rubber seal (-20℃~80℃ resistance), ensuring airtightness for 6+ months with most tubeless valves.

Application Areas

Application areas for the XC-MA25X33HL-27.5ER carbon bicycle rim:

• Road Cycling:

Excels on smooth roads, with 30mm aerodynamic sidewalls and 28mm width boosting speed and pairing well with 25C-28C tires—ideal for races, training, and endurance rides.

• Fitness/Recreation:

 Lightweight and vibration-absorbing, it enhances comfort for commutes or casual rides, with customization for personal style.

• Time Trials/Triathlons: 

Streamlined 30mm height reduces drag, while rigid carbon ensures efficient power transfer for competitive gains.

Technical Parameters

Customized Weaves & Finishes:

Customized Holes:

Weight Check:

Clean burrs ＆ residues:

Rim Diameters Check:

Cleaning:

Packing:

AM-MA25X33HL-27.5 Product Show