The Great Wheel Ball-Bearing Debate Continues

Can too tight be just as bad as a little loose?

THE QUESTION
There seems to be a lot of confusion out on the roads about whether or not there should be any play in a wheel’s axle.  Do some wheel makers design play into the hubs? Is a little play dangerous? Can wheel bearings be adjusted too tight?

THE REPLY
Look past the deep-section rims, and paddle-shaped aero spokes, and ignore the direct-pull hubs, because the largest potential increase in your wheel’s performance may be rotating much closer to the axle. When a wheel is first built, any free play in the bearings will cause false readings at truing stand’s run-out gauges when it is trued and tensioned (typically, digital or dial indicators that rub on the top and to one side). To eliminate this variable, the threaded hub adjustments are purposely tightened slightly over to prevent unwanted lateral play.

Almost all new wheels are then shipped in this preloaded condition, but when we take them out of the box and give them a spin, the hubs feel super smooth because the bearings are new and the balls and races are polished. When the wheel is installed, however, the compressive force of the quick release mechanism squeezes the axle and further overloads the wheel bearings. Racing mechanics know about this and they preset the wheel bearings with a tiny amount of free play. This compensates for the shortened axles and allows the wheel to roll noticeably smoother.

We asked one wheel builder what he did with new wheels. “I would adjust the bearings a little at a time, and then put them in the frame and fork, close the quick releases and check for free play until the wiggle faded away exactly at the moment that the lever clicked shut. I also used the same amount of closing force on the quick release levers to insure that I benefited from those adjustments on the road.”

Racing wheels cost a pretty penny, and much hype is made about the quality of bearings used by prestigious brands, but you will be throwing away bearing life and dramatically increasing friction by installing your already pre-loaded hub bearings on your frame and then squeezing them further with the quick releases. If all of the claims from ceramic bearing makers are correct-that smoother-rolling bearings can save you a handful of seconds a mile-you probably should use this simple tip to your advantage. Have your shop do this when you purchase your wheels, or adjust them at home. It’s free speed.

WHAT ABOUT CERAMIC BEARINGS?
Long ago we asked posed this question to long-time industry wheel man John Neugent (Neuvation Cycling)  and this was his reply…

On the hubs (not the bottom bracket where the contact seals are more aggressive) I am of the opinion that you get virtually nothing from ceramics.  I sell a boat load of them (almost $50K so far this year) but, in my opinion, if one were to take the seals and grease out and just oil a standard Abec 5 bearing, you would be 99.9999% of the same rolling resistance and save a ton of money.  They get virtually all of their performance increase from the low contact seals and light grease they use and there is nothing stopping someone from doing the same with their stock bearings.  They would need to stay on top of the lubing but that’s not a big deal.  Remember when hubs came with oil holes?

 

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