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 standard bottom bracket size?
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.
Are all 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.
How do I determine bottom bracket spindle length?
The best way to find out which spindle length you need is by looking up the specs. (The alternative is trial and error…) Spindle length and the resulting chainline have some leeway. If you are within 2-3 mm of the “correct” 43.5 mm or 45 mm, you are doing quite well.
What does BC1 37×24 mean?
‘BC1. 37×24 ROAD’ Means an ISO/’English’ threaded bottom bracket shell, 68mm wide is the road standard width. Shimano external threaded BB cups thread right into that, and all 24mm axle road cranks go right in.
Can I use a 68mm bottom bracket in a 73mm shell?
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.
Does spindle length matter on bottom bracket?
The critical thing is your spindle length: as long as you can set up the correct chainline you will be good to go. But, again, best never to mix standards if you can at all avoid it. If you are looking to replace a cottered crank setup with a square taper setup, then look no further than a cartridge bottom bracket.
What is a 68 73 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.
What is BB92 bottom bracket?
The BB92 standard, also known as Shimano Press Fit, uses a bearing housed in a nylon or aluminum cup that is pressed into a bottom bracket shell that measures 92mm wide. This standard is designed around the 24mm spindle diameter used by Shimano.
Do I need spacers on my bottom bracket?
Much like GXP, you don’t need to add any spacers to the bottom bracket if you have a 73mm shell, but you will need to add a 4.5mm spacer to the right-hand side of the crank axle, unless you’re using a chain guide, in which case a 2mm spacer is required instead, along with a 2.5mm spacer on the right-hand side of the …
What is crank spindle size?
Crank spindle diameter is 30mm from end to end. Crank spindles are 30mm and then have a step-down to 28mm to lock on the non-drive side bearing. Road version designed to work in frames shell width from 68mm to 86.5mm. Mountain version designed to work in frames shell width from 73mm to 92mm.
What are the different sizes of bottom brackets?
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.
Why are there so many different tools available for bottom brackets?
There is a wide variety of tools to choose from due to the variety of threaded bottom brackets, complicated further by the various solutions that tool designers have come up with to fit each BB profile.
What is the difference between and/or and threaded bottom brackets?
And/or is an important distinction because bottom bracket tools normally do one or the other when it comes to press-fit bottom brackets, for example. Low-end, mass-market through to mid-end bikes use threaded bottom brackets which install into threaded bottom bracket shells.
How do I determine the bottom bracket standard in my frame?
To accurately determine the bottom bracket standard in your frame, it is best that you remove your crankset, and any installed bottom bracket cups or bearings. Then measure both the inner diameter and width of your frame’s bottom bracket shell. The chart below lists most of the current bottom bracket standards found on today’s frames.