Bottom brackets are probably the least glamorous of all bicycle components. Most folks tend to install them and then forget about them until a mysterious noise or knock starts to emanate from the cranks’ vicinity.
My previous experience with external bottom brackets has been disappointing. One unit’s bearings essentially seized after six months, and another’s bearings were lube-free after one season. When it came time to select a compatible BB for my Salsa’s Shimano compact cranks, I decided to give Shimano’s Dura-Ace (SM-BB7900) unit a try.
While the BB7900 bottom bracket may reside in the top-tier Dura-Ace group, its appearance is very unassuming. There are no blingy color options to appease the style-conscious parts matchers. If you didn’t know better, you might think that it was a mid-range product and not one aimed at high-mileage racers.
But pretty colors and laser etching don’t mean squat if a bottom bracket’s bearings and seals are no good. To test Shimano’s claims of “improved seals,” and “smooth rotation and long-term durability,” I decided that I would install the bottom bracket and then basically ignore it.
And ignore it, I did. For twelve months I rode the BB7900-equipped bike on pavement, dirt, gravel, and everything in between. I rode sans-fenders, and hosed the bike off when I couldn’t see the decals on the downtube. Maintenance consisted of wiping down the exterior of the cups with a discarded t-shirt. Approximately ten months into the experiment I pulled the cranks to change a chainring. The external seals were dirty, but the bearings still felt smooth. I checked the cups’ tightness–more out of habit than anything else–and found them as snug as when they were installed.
With a street price (read, eBay) price of around $35, Shimano’s Dura-Ace bottom bracket is a tremendous bargain. It’s outlasted and outperformed competitors’ products selling for 2x-3x more, and shows no signs of giving up anytime soon. When it came time to build up my Rawland rSogn, I grabbed another 7900 bottom bracket faster than you can say, “Add to cart.”