This bottom bracket is for use with a non threaded road bike BB shell, that measures at a width of 68 mm and a shell inner diameter of 42 mm, when you have a 30 mm crank spindle you want to use with your bike. We have a full run of bearing options in this platform, angular contact steel through the top of the line XD15. All of these bearing kits will come with C clips, a wavy washer, 5 narrow spacers, and the bearing seals.
If you have a Cervelo R5CA frame with a 79 mm BB width (42mm ID) - This BB30 will work for you.
For your dirt pedal bicycle this can also be the choice for you if you have a 68 or 73 mm shell width combined with a 42 mm inner diameter. This BB will allow you to run a 30 mm spindle to your dirt loving delight.