A basic frame check can be easily carried out by an individual using a check gauge. This is a very easy check to undertake and requires no specialist knowledge.
The gauge consists of two sides a “GO” and a “NOGO”. The frame should permit the GO side go go in, the NOGO side should be too large to go in.
- This gauge is no substitute for accurate measuring with a calibrated micrometer. It is a quick check only.
- There is a reasonable manufacturing tolerance that has been applied of 0.02mm (or just under 0.001″. )
- The material has been left for the choice of the machinist. Brass, Steel, Aluminum are all acceptable
For BBright and BBCorrect (CERVELO and FACTOR)
Cervelo and Factor bikes use BBright or BBCorrect bottom brackets. At some point in the past they modified the tolerance range to make it wider. The gauge is for the original tolerance (pre-widening). Please be aware that their new tolerance range is so wide that no bearing manufacturer (SKF, NTN, NSK,FAG) will warranty their bearings in Cervelo and Factor frames, they have categorically stated the range is too wide to function correctly.
|Gauge Type||Bottom Bracket Suitability|
|41mm GO NO GO||BB86, BB92 (All variants of Shimano standards Road and Off Road)|
|42mm GO NO GO||BB30, BB30A, BB386 (This is a very rare standard)|
|46mm GO NO GO||PF30, PF30A, BB386EVO*, BBright (Cervelo/Factor), BBCorrect (Factor)|
*Most people refer to BB386EVO as BB386. BB386 as it was intended is an extremely rare standard. Most frames that are described as BB386 (46 x 86.5mm) are technically B3