Editor’s note: This story originally ran in the July issue of Bike.
Bottom Bracket Racket: Chris King's Answer To Press-Fit Woes | $165 | chrisking.com
If I had to name the source of the most considerable frustration during my time as a mechanic it would easily be press-fit bottom brackets. Even a skilled mechanic armed with expensive measuring tools, bearing presses and sleeve-retaining compounds, is not guaranteed a good interface. At the last shop where I worked, we'd send dozens of brand-new frames back each year because the bottom-bracket shell didn't meet tolerances.
It's difficult to make frames at a high volume and meet the tight tolerances required for bearings to push in just right. If a bore isn't perfectly round or is a fraction-of-a-millimeter off, the bearing won't seat properly. Press fit's biggest challenge is that it requires higher accuracy than bike manufacturers are willing to adhere to.
In an attempt to rectify the problem, manufacturers decided to shove bearings inside a plastic housing designed to make up for frame-tolerance discrepancies. Shockingly, installing a piece of plastic in one of the most critical areas of the bike doesn't really work.
The failure of Shimano and SRAM to make a decent press-fit bottom bracket has opened up a market for solutions from brands like Chris King, maker of some of the most precise and durable bike parts in the world. King makes everything in its environmentally friendly facility in Portland, Oregon. This includes the bearings used in all its components, which might be the most impressive aspect of King's business. The hardened steel used is so tough, and the craftsmanship so perfect, that it's not uncommon for a Chris King bearing to outlast several bikes. Removing the bearing's dust shield, rinsing it with degreaser and re-greasing it can easily restore a frozen King bearing to like-new condition without replacing a single part.
King Press Fit Bottom Brackets feature King's indestructible angular contact bearings in precision-machined aluminum cups that can be installed and removed multiple times without damaging and won't flex and deform like plastic. King still relies on the frame to be manufactured correctly, but its engineers can at least attack the press-fit problem from their meticulous machine shop, ensuring that at least one part of the equation is made to exacting standards.
I installed this Press Fit 30 bottom bracket into a carbon Specialized Stumpjumper and forgot about it for a season without a single groan, moan, creak, click or migration from the frame–like what can happen with the $50 plastic bottom bracket that comes on the bike. After removing the trusty King cups for the above photo, I discovered, to no surprise, that the bearings still felt as smooth as the day I installed it. Press fit may be here to stay, but I'll rest easier knowing that there's a solid fix to all this madness. – RP