OSBB is the acronym for Specialised’s OverSized Bottom Bracket. It features a 46mm diameter and 61mm width shell. As it is unique, it requires a unique bottom bracket to mate BB30 cranks to it.
The cups come installed with one of two CeramicSpeed bearings. The Standard Bearing has ceramic CS balls and hardened-steel races. The Coated Bearing has the same balls running on hardened-steel races with a 3-micron thick metallic coating making the races harder and smoother, increasing service life and reducing friction.
In The Box
- 2 cups with bearings installed.
- 2 3mm spacers.
- 2 1mm spacers.
- 2 0.5mm spacers.
- 2 dust covers.
- Wave washer.
- Telescoping spacer tube.
- 10ml All Round Grease.
- Sticker sheet.
Specialised’s bottom bracket standard is narrower than most. As a result, you’ll find several spacers packaged with. They take up the space from the 61mm of the shell to the 68mm that is more common for BB30 cranks, which have also have a 30mm spindle.
The OSBB and BB30 are both performance enhancers. CeramicSpeed’s bottom bracket improves the performance of both. It’s also nearly zero drag. Standard Bearings typically have frictional drag of 0.3-0.4 watts per set. That’s in the range of a 75% drag reduction compared to conventional bottom brackets. The bearings last at least three times longer than other bearings.
Performance can be customised by changing the grease. All Round comes with, but you can change it to TT and Track Grease for less drag or to LongLife for greater durability.