How Do I Know What Size Bottom Bracket I Need?

How do I know what size bottom bracket I need? To find out the size of bottom bracket needed, measure the inside of the bottom bracket shell in your frame, it will be 73mm, 70mm or 68mm. Some older frames may have Italian threaded bottom brackets, instead of the more modern English.

What is the diameter of a bottom bracket?

Bottom Bracket Standards

BB Standard Frame BB Shell Inner Diameter Common Shell Width
Specialized OSBB Alloy 42mm 68mm (Road) 84.5mm (Mountain)
Cannondale BB30a 42mm 73mm 83mm (Cannondale BB30A-83)
PF30 46mm 61mm (Specialized OSBB/FACT) 68mm (Road) 73mm (Mountain) 83mm (Downhill) 100MM (Fat Bike)
BBRight (Press Fit) 46mm 79mm

Will any crankset fit on my bike?

In most cases three-and two-piece cranksets are compatible with the same bottom brackets so long as the axle is the same diameter. They are commonly used in conjunction with the mid-style bottom bracket standard.

How do you match a crankset with a bottom bracket?

What cranks fit PF30?

Crankset Standards

Crankset Spindle Diameter Bearings
GXP 24mm/22mm 24x37 (Drive) 22x37 (Non-Drive)
SRAM DUB 29mm 29x42
BB30 30mm 6806 (Drive) 6806 (Non-Drive)
PF30 30mm 6806 (Drive) 6806 (Non-Drive)

Related guide for How Do I Know What Size Bottom Bracket I Need?


How do you measure a bottom bracket spindle?

Pull off both crank arms, then measure the spindle of the BB, that's what the Shimano Crank is saying it needs. When you measure spindle length, you need to only measure to the ends of the square taper. Some spindles have threaded bits that extend beyond the square taper. Don't include those in that measurement.


How do I know if my bottom bracket is English or Italian?

The key difference is in how the two thread into the bottom bracket shell. Like pedals, one side of a BSA standard bottom bracket shell is reverse (left) threaded, while both sides of an Italian standard bottom bracket shell are regularly (right) threaded.


What size is BB30?

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.


How do I know if my bottom bracket is worn out?


What is the bottom bracket on a bike?

The bottom bracket is the bearing system between the cranks. It sits inside the part of the frame called the bottom bracket shell. The bearings are held in the shell by an adaptor or a cup. The spindle connects the two cranks to one another and to the bearings.


Are all Shimano cranksets compatible?

Nearly all pinch-bolt style Shimano road cranks are able to be interchanged in equivalent lengths. Stages Power R right-side Shimano road power meters can also be used with any Hollowtech II compatible left crank arm.


How do I know what crankset to get?

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.


How many teeth does a Shimano bottom bracket have?

Phil Wood uses a similar splined design to the Shimano bottom bracket. The difference is an 18-tooth versus a 20-tooth as per the Shimano design.


Why does my bottom bracket creak?

As the crank arms are rotating, the bottom bracket will make a dry creaky noise, and is usually caused by axle oscillation around dry bearings, where the grease inside has been washed out of the many contact points,” he says. Many bottom brackets do, and these can also dry out and click.


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