The BB4129 bottom bracket solves the problem facing riders who have BB86/BB89.5/BB92 frames, which were designed around 24 mm cranks, but have DUB cranks with 28.99 mm axles. Although there is enough room for small bearings, we realize that a single row of balls isn’t enough to ensure durability, which is why we added a second row on each side to help distribute the weight over a greater area.
To keep this bottom bracket running smoothly even after a wet day on the road, we also use high quality seals to keep out the water. Since the bearings sit directly on the frame, we take care to carefully machine the cups so they fit perfectly. This bottom bracket uses Premium bearings or an upgrade to stainless SPB (Sapporo Precision Bearings) bearings.
This bottom bracket is a great solution for riders looking for a long-lasting bottom bracket that fits a BB86 frame but who uses cranks with 28.99 mm DUB axles.