Engineered specifically for demanding cycling applications, this ABEC 5 radial bearing provides superior rotational smoothness, reduced rolling resistance, and long-term durability. By utilizing Grade 5 Chromium Steel balls and mirror-polished 52100 High-Carbon Chromium-Alloy races, Enduro delivers manufacturing tolerances twice as tight as standard ABEC 3 options.
The standout feature of this bearing is its dual-seal combination. It features a full-contact LLU seal facing outwards toward the elements to stop water, dirt, and trail grime from entering, alongside a light-contact LLB seal facing inwards to minimise drag while keeping high-pressure grease contained around the balls.
ABEC 5 Precision Rating: Features Grade 5 Chromium Steel balls and mirror-polished races for ultra-smooth operation and tight tolerances.
LLU/LLB Combination Sealing: Outer LLU full-contact seal guards against harsh trail contaminants, while the inner LLB seal reduces rotational friction.
High-Pressure Rheox Grease: Packed with waterproof grease designed to withstand severe weather, washdowns, and high load forces.
Dimensions: 17 mm (Inner Diameter) x 30 mm (Outer Diameter) x 7 mm (Width)
Bearing Code: 61903 / 6903
Precision Rating: ABEC 5
Material: 52100 High-Carbon Chromium Steel
Seal Type: LLU (outer) / LLB (inner)
✅ Hub & Bottom Bracket Upgrades: Ideal for riders rebuilding high-end hubs or bottom brackets that require a precise 17 x 30 x 7 mm fitment.
✅ All-Weather Reliability: The dual-seal design prevents mud, water, and road grit from contaminating the races during wet rides.
✅ Smooth Rotational Efficiency: Delivers significantly lower rolling resistance compared to basic ABEC 3 replacement bearings.
❌ Suspension Pivot Points: Designed for high-speed radial rotation, not the extreme oscillatory loads of frame suspension pivots (which require MAX full-complement bearings).
❌ Ceramic Enthusiasts: Those seeking ultra-lightweight, zero-corrosion ceramic bearings may prefer Enduro’s Hybrid Ceramic or XD-15 options.
❌ Incorrect Hub Sizing: Ensure your hub shell or bottom bracket specifically requires a 61903/6903 size (17x30x7 mm) prior to installation.
When pressing new bearings into your hub shell or bottom bracket, always use a dedicated bearing press or drift that contacts only the outer race of the bearing. Applying press force to the inner race or seal can damage the internal balls and races before you even take your first ride!
