Still, it’s not impossible, and given the modularity of Trek’s frame design, it wouldn’t warrant a complete redo of the entire frame, either.įor bottom bracket-related issues that a shop can’t solve, Trek has little choice but to supply a new frame, or bring the original one back in-house for an expensive, and time-intensive, repair. Trek’s current BB90 shell uses essentially the same width as a wide-format T47 shell, but its diameter is much smaller so there would be some redesign involved. Currently, I know of only two: Enduro Bearings offers oversized bearing cartridges that press into the frame a little tighter (which is useful for oversized, but not misshapen, bearing bores), and Token recently introduced a dedicated thread-together system, but it relies on undersized bearings that introduce other problems. And unlike with other press-fit systems on the market, there are few aftermarket solutions available. Trek touted a weight savings of about 40g relative to conventional outboard threaded cups, and with fewer parts, there was supposed to be less chance of creaking relative to other press-fit systems.īut Trek’s system relies on a level of manufacturing precision that doesn’t seem attainable in reality. Press-fit was already a thing, but BB90/BB95 eliminated cups altogether by pressing the bearings themselves directly into the frame itself (BB95 is the same as BB90, but with wider bearing spacing to suit mountain bike drivetrains). Trek heaped huge piles of praise on its the then-revolutionary BB90 system it launched in 2007. This Orbea Orca uses a BB386EVO press-fit shell, which uses nearly identical internal dimensions to a wide-format T47 setup. One of the mandates for the original developers of T47 was that it should be easy for frame manufacturers to make the switch from existing press-fit formats. Shown here are two bottom brackets designed for the narrow-format shell: the one at top is designed to fit a wide-format 24mm crank (such as Shimano), while the other one is designed for a narrow-format 30mm crank (such a Specialized S-Works carbon model). Both versions of T47 use the same shell diameter, but there are two shell widths supported for brands that prefer wide-format or narrow-format bearing spacing. The T47 threaded bottom bracket system is basically the same as PF30 and BB386EVO, but with threaded ends and threaded cups instead of smooth bores and press-fit cups. The only issue, however, is that none of the bigger brands have bought into the idea - seemingly until now. In other words, it’s like the English threaded bottom bracket format we all know and love, but with inflated dimensions to better suit modern frame materials and crank spindle diameters, and with the same ease of installation, removal, and maintenance - not to mention a far greater chance of quiet operation. In essence, T47 is the same as PF30 and BB386EVO, but with metal threads instead of a smooth, cylindrical bore. But those bearing spacings mimic what’s used currently, and the bottom bracket shell’s internal diameter is essentially identical to PF30 and BB386EVO. There are two versions: one with narrower bearing spacing, the other with wider bearing spacing. T47 instead utilizes an oversized threaded format. So yes, press-fit may not be terrible in theory, but overall, it’s bad enough that it’s an outright deal breaker for many. And plastic ones aren’t really meant to be reused at all. And worse yet, those problematic frames are difficult to properly diagnose, and can result in months of annoying creaks, groans, and curses in the meantime.Īnd even when press-fit does work properly, there’s still the matter of multiple specialty tools required for service - one of which is often a big hammer - and the fact that the cups themselves get looser every time they’re reinstalled. Mass manufactured bikes have been more hit-and-miss, particularly when they’re made of molded carbon fiber. However, it seems that most of those positive experiences have come from smaller-volume builders that can spare the time and energy to ensure it’s done properly. I don’t necessarily have fundamental issues with the concept, and I’ve ridden countless examples that work quite well. I’ve made my disdain for press-fit bottom brackets clear over the years. The handful of years since have seen mere glimmers of that hope - mostly amongst the custom crowd - but now Trek is rumored to be the first major brand to take the plunge. The T47 oversized threaded bottom bracket shell design was introduced in 2015 to much fanfare and claims that it would finally provide a truly universal standard that everyone in the industry could support.
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