no3puttchad
07-30-04, 04:06 PM
I have a new frame, and need a BB for it. How can I tell the right size? Is the width the measurment of bb shell on the frame?
Bicycle Mechanics - How to tell the BB size
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Retro Grouch
07-30-04, 04:22 PM
I have a new frame, and need a BB for it. How can I tell the right size? Is the width the measurment of bb shell on the frame?
There are actually two key width measurements.
The first has to do with your frame. Most road bike bottom bracket shells are either 68mm wide (English threading) or 70mm wide (Italian threading). Mountain bikes with their wider rear triangle tend to have 73mm wide bottom bracket shells (English threading).
The second has to do with your crankset. The spindle length of your bottom bracket has to match your crankset. Most of the newer Shimano cranksets take either a 109.5mm spindle length (double chainrings) or 118mm (triple chainrings).
There are actually two key width measurements.
The first has to do with your frame. Most road bike bottom bracket shells are either 68mm wide (English threading) or 70mm wide (Italian threading). Mountain bikes with their wider rear triangle tend to have 73mm wide bottom bracket shells (English threading).
The second has to do with your crankset. The spindle length of your bottom bracket has to match your crankset. Most of the newer Shimano cranksets take either a 109.5mm spindle length (double chainrings) or 118mm (triple chainrings).
canuck88
08-09-04, 07:41 AM
Have you tried calling the manufacturer and asking them? Chances are it's 68mm, but you never know. The spindle length will largely be determined by which crankset you are using (again, your manufacturer will likely know). If you hate the telephone, take it down to the shop where you plan to buy the BB and have them fit one.
live311
08-09-04, 07:53 PM
What make, model, and year is the frame?