Riders and mechanics rebuilding a 24 mm spindle external bottom bracket who want an upgrade over standard steel bearings.
The Enduro CH MRA 2437 LLB is a 24 x 37 x 7 mm replacement bearing for external-cup bottom brackets that run a 24 mm spindle, the Shimano Hollowtech II standard. Rather than replacing the whole BB when it goes rough, you can press in fresh bearings and keep the cups.
It's an angular contact design, so it's built to handle the sideways loads a bottom bracket sees with every pedal stroke. Grade 5 silicon nitride ceramic balls run on 52100 chromium steel races, cutting friction and wear compared with an all-steel bearing.
LLB dual-lip labyrinth seals and a 90% fill of waterproof grease keep the weather out. Angular contact bearings are directional, so they must go in the right way round, with the black seal facing in.
Ceramic hybrid
Silicon nitride balls on steel races for low friction and long life.
Angular contact
Built for the side loads a bottom bracket sees.
Fits 24 mm spindle BBs
Replacement for Shimano-style external cups.
Well sealed
LLB labyrinth seals and 90% grease fill.
Bearing
In the box
Angular contact
The races are shaped to take side loads as well as straight-down loads, which suits a bottom bracket where pedalling forces push the spindle sideways with every stroke.
Ceramic hybrid
Silicon nitride ceramic balls run on steel races, removing steel-on-steel contact inside the bearing to cut friction and wear.
LLB seals
Dual-lip seals ride in a groove in the race to form a labyrinth that keeps water and grit out and grease in.
Great for
Maybe not for
24 mm bore, 37 mm outside diameter, 7 mm wide. Suits external bottom bracket cups built around 24 mm spindle cranks when the cups allow bearing replacement. Sold as one bearing; a bottom bracket uses two. Angular contact: install with the black seal facing in.
Mind the direction
Angular contact bearings only work properly one way round. Fit them with the black seal facing inwards, towards the middle of the bike, and set preload correctly when you install the cranks.
Press, don't hammer
Use a bearing press with drifts that push on the outer race. Ceramic balls are hard but a hammer can still damage the races or seals. If you don't have the tools, bring the bike in and we'll do it.
Enduro makes bicycle bearings in high-carbon chromium steel, 440C stainless steel, ceramic hybrid and XD15, and engineers them with the deepest possible grooved races and dual-lip labyrinth seals for protection against the elements.
