Almost any decent hub these days runs on sealed bearings of one type or another. This is why it's important to have suppliers who can deliver top quality sealed bearings. Cognoscenti Cycles relies on a few companies to keep us stocked with some of the best bearings around. Companies like CeramicSpeed, Enduro, F1 Ceramic and Boca Bearings offer what we are looking for. Bearing technology is quite sophisticated and you definitely want perfectionists making sure that top end materials are being used and that tolerances are as tight as they can be.
Sealed bearings for bicycle hubs fall into two camps. All stainless steel bearings were both the ball bearing and the ground race are made of the same material. That bearing is very strong but isn't the highest performing bearing out there. Next level bearings move into the world of ceramic balls that can be made almost perfectly round, enabling them to out perform steel easily. Their hardness is also legendary. Many racing cyclists seeking the lowest possible rolling resistance are taking advantage of high speed ceramic hybrid bearings that out perform most everything else. This is why many hub makers are offering an upgrade to ceramic hybrid types. F1 Ceramic is a USA based company that has been making all their bearings in house for the last 13 years. Their bearings have been on bikes that have been ridden in the Tour de France, Paris Roubaix, the World Championships, The Vuelta Espana, the Olympics and numerous National Championships. That's a long list of success's and certainly would fill anyone with confidence in using their top end bearings.
Below is a photo of Enduro's Zero Ceramic Grade bearing. Made with oversized Silicon Nitride grade 3 balls that roll on races that have been cryogenically frozen to increase hardness and longevity. They employ silicone seals which are more slippery than rubber seals. When reviewed these bearings win independent wattage output tests when stacked against the competition. The definite "go fast" option! If your curious just how high end a grade 3 silicon nitride bearing is here are a few specs that will impress you. The high precision Grade 3 pure ceramic balls are 3/1,000,000 from exactly round in sphericity! That's no typo either. They are 7 times harder than steel and weigh 60% less. Their friction hovers around zero. Imagine these in your hubs...
Enduro's ZERO Ceramic Grade with silicon nitride balls. Made in California.
Enduro also makes top end ceramic bearing loaded bottom brackets and pulleys for your rear derailleur. So after you've sorted out your hubs you can move onto the other parts that need a speed bump.