The last few years have seen some fantastic improvements to road and mountain bike technology and along with this comes a new phenomenon called BBC - bottom bracket confusion. To try help our clients out I thought it wise to publish this spec list.
If you need help beyond what you see here please e-mail me at clive@glorycycles.com
| Bottom Bracket Thread Name | Nominal Thread Description | Cup Outside Diameter | Shell width | Shell Inside Diameter |
|---|---|---|---|---|
| ISO/English or BSA | 1.37 in x 24 TPI | 34.6-34.9 mm Left-hand thread drive side | 68 mm (73 mm Oversize)(83 mm Some Downhill & FR bikes)(100 mm "Fat bikes") | 33.6-33.9 mm |
| Italian | 36 mm x 24 TPI | 35.6-35.9 mm Right-hand thread both sides | 70 mm | 34.6-34.9 mm |
| French | 35 mm x 1 mm | 34.6-34.9 mm Right-hand thread both sides | 68 | 33.6-33.9 mm |
| Swiss (very rare) | 35 mm x 1 mm | 34.6-34.9 mm Left-hand thread drive side | 68 | 33.6-33.9 mm |
| Chater-Lea (very rare) | 1.450 in x 26 TPI | oversized Left-hand thread drive side | ||
| Whitworth (obsolete, found on older English 3 speeds) | 1-3/8 in x 26 TPI | 34.6-34.9 mm Left-hand thread drive side | 71/76 | 33.6-33.9 mm |
| O.P.C. Ashtabula | Male threads on crank 24 tpi (most) 28 tpi (Schwinn, Mongoose) | 68 mm (2.68 in) wide | 51.3 mm (2.02 in) (approximate) | |
| O.P.C. Fauber | Male threads on crank | 68 mm (2.68 in) wide | 45 mm (1.77 in) | |
| Raleigh | 1 3/8 in x 26 tpi | 34.6-34.9 mm Left-hand thread drive side | 33.6-33.9 mm | |
| BB30 | Press fit, not threaded | No cups | 68mm (road) or 73mm (MTB) | 41.96mm |
| Press Fit 30 | Press fit, not threaded | 46mm Plastic Cups | 68mm (road) or 73mm (MTB) | 46mm |
| BB90 | Press fit, not threaded | No cups | 90mm | 37mm |
