How do I know what is the right bottom bracket for my old road bike?

Asked by: Rachel Pervis

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 size bottom bracket do I need road bike?

The majority used the BSA standard bottom bracket with a 68mm wide shell and a 34.8mm diameter.

How do I choose the right bottom bracket?

To know the size of Bottom Bracket that you require, simply measure the length of the inside of your Bottom Bracket shell. It’s usually 73mm or 68mm on all modern bicycles. Older bicycles may have the less conventional Italian threaded Bottom Brackets, unlike the more modern English Threaded Bottom Brackets.

Are all road 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.

Are all bottom brackets compatible?

In general terms, most cranksets can be fitted to a variety of bottom bracket shells, though much of this compatibility depends upon the availability of suitable hardware (see next section). Any incompatibilities that do arise are often related to the length and/or diameter of the crank axle.

Can I fit a 68mm bottom bracket in a 73mm shell?

You could install it, but it will shift your chainline, shift the centerline of your feet, clearance issues might arise on the non-drive side, and you might be leaving some BB shell threads exposed on the non-drive side as well.

What is 68mm bottom bracket?

The 68mm and 73mm dimension measure the width of the bottom bracket on the frame of the bike with no BB installed, simply the width of the shell. Most road bikes that use a threaded bottom bracket measure 68mm wide and most cross country/trail mountain bikes measure 73mm.

How do I measure my bottom bracket?

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.

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 difference between BB30 and BSA?

BSA is English standard and have screw thread inside the hole ,usually use in shimano,while BB30 is Italian standard and don’t have screw thread, usually use in CP.

How many types of bottom brackets are there?

two main

There are two main types of bottom bracket design, one with a threaded shell which the bearings screw into, or a press-fit design which the bearings press into the shell. Bottom brackets are largely distinguished by the shell and axle width and the diameter of the shell and axle.

Does changing bottom bracket make a difference?

In other words, bottom brackets do different significantly drag-wise in terms of percentages but as far as actual watts are concerned, we’re talking relatively small numbers here that most general cyclists aren’t likely to notice.

What do the numbers on a bottom bracket mean?

The numbers ranging from 86 to 132 refer to the nominal width of the shell in millimeters, which is not related to the press fit of the bearings. These bottom brackets will vary in the width of the dust sleeve used for that different widths.

How many spacers does a 73mm bottom bracket have?

For 73mm Shimano HTII bottom brackets



If your bottom bracket shell is 73mm wide, you only need one 2.5mm spacer fitted to the drive side.

Do cranks need spacers?

For all cranksets with a constant diameter spindle (30mm, 29mm DUB and 24mm), spindle spacers are used as needed to remove any side-to-side play of the crank, and to center the crank in the frame. For most installations, the included spacers will be enough to properly position the cranks in the BB.

How do you install a Shimano bottom bracket?

What Type of Bottom Bracket do I Have?

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).

How do I measure my bottom bracket?

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.

What is the difference between BB30 and BSA?

BSA is English standard and have screw thread inside the hole ,usually use in shimano,while BB30 is Italian standard and don’t have screw thread, usually use in CP.

Is BB386 compatible with BB30?

“The BB386 EVO cranks are compatible with almost every BB shell standard (BSA, BB30, PF30, BB86),” says Jason Miles of FSA.

What cranks fit BB386?

Standard 24mm cranks from Shimano, SRAM and others fit inside BB386 EVO without a problem. The width matches the axle width and there are a host of bearing and cup options to connect crank and BB shell. For 30mm axles, most cranks also fit.

Are BB30 and PF30 the same?

ARE PF30 & BB30 the SAME? No they are not the same. But they are also not all that different. 6806 is a number you’ll see describing the bearings used for both pf30 and BB30.