There are a number of BB standards in the bike industry right now. Here is what you will find on our bikes, and why.

 

Traditional: The BSA standard. The standard forever. A steel BB spindle, 17mm in diameter, turns within a 68mm or 73 mm shell and upon sealed cartridge ball bearings that are threaded into the BB shell. Not particularly light, not especially stiff (by today’s standards), but reliably durable and definitely cost effective.

 

External Bearing: The BB shell is still 68mm or 73mm wide and just under 35mm in diameter, but the bearings have been moved outside the BB shell (Shimano Hollowtech II, SRAM GXP, FSA MegaExo). This allows the spindle diameter to be increased over 40% to 24mm and hollowed for a huge stiffness increase with a significant weight reduction. The larger diameter spindle does not compromise bearing size because all bearings now reside outside the frame. The spindle is also better supported with bearings nearer its ends rather than its center.

 

PressFit30: PressFit30 (SRAM) is a derivative of the BB30 (FSA) system. BB30 increases the spindle diameter to a whopping 30mm for the ultimate in stiffness. But because the BB shell’s inside diameter is also increased from just under 34mm to 42mm, bearing size is not compromised. The challenge with BB30 is that bearings are pressed directly into the frame, leading to durability issues if there are any frame or bearing tolerance deviations. The beauty of the PF30 system is that bearings are housed in nylon cups that are pressed into the frame’s bottom bracket shell. Bottom-line advantages of the PF30 system over BB30? Improved bearing-to-shell interface, greater bearing durability and simplified installation.

 

BB386EVO: The BB386 EVO bottom bracket design amplifies the benefits of the proven BB30 and PF30 system. It takes the lighter, stiffer 30mm alloy spindle from the BB30 design, incorporates press-fit bearing cups from the PF30 system and marries both to a wider 86.5mm BB shell (which is the same width as on a standard 68mm shell with external bearings). All without changing Q-factor. Why a wider shell? It allows us to increase the diameter of our seat and down tubes at the BB shell a full 30%, for increased stiffness where you really need it. We can also optimize chainstay design with an increased diameter that doesn’t crowd the rear tire.

All our frames and forks are tested continually to meet or exceed (in some cases, well exceed) EN standards 14764, 14765, 14766 and 14781 as well as the new ISO 4210 standards. We conduct these tests at our frame manufacturing facilities, but we also use EN accredited testing laboratories such as Intertek and SGS to verify the results of our own tests. If these tests aren’t telling us everything we want to know about our bikes, we increase the loads and cycles, or we determine another way to test. Where current hydraulic testing machines, jigs and hardware aren’t up to the task of emulating some of the forces and impacts our bikes might be subject to, we’ve designed our own.

 

We relentlessly cycle test for fatigue from pedaling and torsional forces on every single frame size, with deflection tests for stiffness at every point of the frame. Brutal impact tests with massive weights dropped on fixed frames or forks are performed. Then reversed, with weights attached to the frame, the frame hoisted to a given height depending upon product type, then released.

 

This destructive testing is enormously instructive and important. And it is in continual process. But it’s our ongoing non-destructive testing of frames and forks fresh off the factory floor that’s just as vital.

 

For our carbon fiber frames, EVERY frame is weighed to make sure it’s neither resin rich nor resin deficient. We also measure the stiffness of each frame in 6 critical areas as a check on lay-up production. Each deflection test must fall within 5% of the standards our machine and field-testing have established. This weighing and stiffness deflection testing guarantees every single frame we produce meets all Jamis manufacturing protocol and will

deliver the ride qualities we defined and demand.