Are all bottom bracket diameters the same?
A frame with a BSA fit is incredibly commonplace. There are 4 widths available with BSA bottom brackets; 68mm, 73mm, 83mm or 100mm. For road bikes, a BSA bottom bracket is always 68 mm wide. Other sizes, and particularly the 73 mm width, is commonplace with mountain bikes.
How do I know what size crankset to buy?
The crank length represents the distance between the centre of the bottom bracket and the centre of the pedal axis. The most common lengths are 170, 172.5 and 175 mm, but it is possible to find cranks between 165 and 180 mm in the market.
Can I use a 68 BB instead of 73?
Multiple spacers are included in order to fit both sizes meaning if you see a BB for sale that says 68/73 it means it will fit both but it includes a couple spacers in the box to make it fit the 68, those spacers (or fewer of them) are not needed if the shell is 73mm wide.
What is BB30 crankset?
The BB30 bottom bracket shell is typically 68mm (road) or 73mm (mtb) wide with an inside diameter of 42mm. Originally the BB30 system was designed to use 30mm diameter crank spindles. A BB30 shell itself is not threaded, instead the bearings press directly into the frame, also known as a direct-fit bearing system.
What are the dimensions of a bottom bracket?
The two major dimensions that differentiate bottom brackets of similar types are the shell width and spindle diameter. Hopefully, we can help clarify some of the more common bottom bracket sizes so that upgrading your cranks can be a simpler process.
What’s the standard thread size for a bottom bracket?
The common threaded bottom bracket uses cups or adaptors with the thread specification of 1.37″ x 24 threads per inch (approximately 34.8mm diameter). The most commonly used term for this standard is “ English ” threading, sometimes abbreviated as ENG.
How big of a bottom bracket do I need for a bbshd?
The BBS02 comes in one size only (68mm) unless you have a custom machined unit with a longer square tapered spindle other than a 68mm. The 68mm BBS02 and BBSHD can easily fit 73mm bottom brackets.
Can a 68 mm bbs02 fit in a 73 mm bottom bracket?
Usually only the 4 notch M33 lock ring will fit on the remaining spindle shaft threads and the second outer lock ring may not fit. What this all means is this… a 68 mm BBS02 can easily fit in both 68 mm and 73 mm shells.
