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Project Sports

Questions and answers about sports

Switching Parts to a New Frame

4 min read

Asked by: Kevin Blake

What is the bottom bracket on a bicycle?

The bottom bracket is a bicycle component used to connect a bicycle’s crankset to its frame, allowing it to rotate independently of the frame itself.

How do I know if my bottom bracket needs replacing?


Quote from video: Changes are likely to be compromised. As well. But if it's just making noises. It might just need taking apart cleaning and servicing re-greasing and putting back.

Are all bike bottom brackets the same size?

There are 4 widths available with BSA bottom brackets; 68mm, 73mm, 83mm or 100mm. This bottom bracket clearly shows you on the outside what bearings have been fitted to the bike. 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.

Can I put any bottom bracket on my bike?

To a certain extent which bottom bracket you end up buying is up to what kind of frame you have. Certain frame materials and drivetrain options only support one type of Bottom Bracket. There are two main types of bicycle bottom brackets in today’s market, namely, threaded and press-fit BB’s.

How do I know what kind of bottom bracket I have?

Quote from video: Found at any point here by hitting the information icon in the corner. The bottom bracket is the bearing system between your bicycles cranks.

How long does a bottom bracket last?

They are still in use and come stock on many bicycles, especially lower end ones. These bottom bracket units can actually be pretty sturdy and can last for years or decades and the user pretty tosses in a new one when it seizes up in a rainstorm.

Do I need to grease the bottom bracket?

In the case of the bottom bracket, you will use the grease when you install it, whether it is threaded, press fit or similar, and in the same way when you install or clean the cranks. The point of contact of the cranks with the bottom bracket should be greased too.

Why is bottom bracket creaking?

Most of the time, the true cause is a loose chainring bolt—tighten them up and that’ll quiet most creaks. After you check the chainring bolts and if you still hear the noise, look at your pedals, crank bolts, seatpost, and seat. By checking these first, you’ll save an hour of digging into your bottom bracket.

Is BB92 the same as PF92?

The frame’s bottom bracket shell inner diameter is 37mm. A bearing with an OD of 37mm is pressed directly into the frame. Trek is moving away from the BB90/95 system to what they call PF92, which is the same as a BB92 (41mm ID shell and 92mm width).

What is the standard bottom bracket size?

The common threaded bottom bracket uses cups or adapters 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 do you measure a bottom bracket on a bike?

Quote from video: In there so frame to frame. And you just want to measure that you're going for the metric. So you can see this is 73. That is 73 millimeters. So usually you're gonna have a 68.

Are all BMX bottom brackets the same size?

BMX frames are made in a variety of sizes and shapes and the tubing where the bottom bracket fits is no different. Bottom brackets for BMX bikes come in 19mm, 19mm mid, 22mm, 22mm mid, and 24mm. Basically, this size refers to the size of the spindle that will pass through the bearing and allows the cranks to spin.

Are all square taper bottom brackets the same?

Bottom Brackets come in a variety of sizes, types and tapers, each manufacturer clearly specifies which Bottom Bracket type would be compatible with their Chainsets and details are included in the product descriptions on our website so this makes choosing the right BB easy.

Do I need to grease the bottom bracket?

In the case of the bottom bracket, you will use the grease when you install it, whether it is threaded, press fit or similar, and in the same way when you install or clean the cranks. The point of contact of the cranks with the bottom bracket should be greased too.

Which is better square taper or hollowtech?

Hollowtech is a bit stiffer and easier to take apart, but square taper will last much longer.