Superfly Cycles

There are several vendors who advertise dry lube or dry treated bearings; that is, bearings that do not use grease.  The claim by the manufacturers is that the bearings have some lube impregnated into the bearing to reduce friction and eliminate the need for conventional lubricants.  Having worked with with coatings in the past, I was a bit skeptical.  Matt at Enduro Bearings was also skeptical so decided to test the bearings on his bearing tester.  The bearing tester at Enduro is a beast of a machine that applies 100 pounds of radial load and 50 pounds of thrust all spinning at 135 rpms.

This machine is an accelerated tester so that bearing failure occurs more quickly than in real life.  For example, a Shimano Dura-Ace bottom bracket bearing lasts 6 hours on this machine and that is a pretty good result.  Incidentally, stock Dura-Ace bearings are pretty decent.  We use this time as a reference for other bearings.  In relation, the same size Enduro ceramic bearing lasts twice as long (over 12 hours) and the Enduro Zero bearings last over 20 hours.  Matt put the dry lube bearing in the tester before lunch and let it run.  He came back 45 minutes later to check the bearing and the to his surprise, the dry lube bearing had literally exploded (see picture).

If you look just below the bearing, you’ll see a metal bearing shield that was on the dry lube bearing.  The bearing failed because the balls in the bearing started to skid due to the bearing races failing from the lack of lubricant.  The bearing races form microwelds or imperfections so when the ball hits these spots, they start to skid. Once the balls start to skid, they start to stack.  Stacking occurs when the leading ball stops rolling (eg. skidding) and the trailing ball rolls into the back of the leading ball.  The dry lube bearings we tested use steel races.  When stacking occurs with steel races, the railing bearing will distort the race to such a point it pops the seal off and the bearing explodes which happened in this case.  Why is the time to failure important?  The obvious reason is that we all want durable bearings.  The corollary to having durable bearings is that is has lower friction, thus faster.  However, think why the bearing failed.  It failed because the lack of lubricant damaged the races.  Whenever imperfections exist on any of the bearing surfaces, resistance increases.