Z-FIRST High Speed 608RS Hybrid Black Ceramic Bearings for Longboard, Inline Skates, Skateboard, Scooters, Skateboard and More (Pack of 4, Black)

Pésima calidad del producto, para usarlo en ruedas de bicicleta no se recomienda

Great quality for the low price. Used to rebuild motor bearing in milwaukee angle grinder. They worked perfectly and made rebuilding the motor easy. The motor spins smoother than before.

I purchased these to replace some trash bearings in a blade balancer I purchased that needed upgrading. These worked fantastically well--almost too well, frankly, since now it picks up VERY small imperfections in weight balance. Oh well, careful what we wish for I guess...

Bought these to replace a set of steel bearings in dishwasher circulator pump. The originals were made in Japan, 608z. The motor was only 18 months old and cost $125; decided to try a bearing replacement this time. Machine tolerances are pretty good. ID bore was probably a hair (maybe a couple thousandth of a mm at most) lager than the 608z steel orininals. Can tell this because a bearing puller was required to remove the original 608z, and these were able to slip over the motor shaft with a few taps from a small hammer. Runout was better than expected from a bearing targeted to the skateboarding market, maybe .5mm at most consudering its nearly impossible to find true specidications the moment a product can also be used for non critical applications like fidget spimners. (The original steel bearings were also, I estimate, about the same .5mm) Free spin time was excellent until, of course, the covers were popped and a dab of bearing grease was applied. All bearings require grease except perpaps full ceramic but even those might want grease in this kind of application. Grease caps of these were a disk of what appears to be stainless, pretty hard stuff, coated with red rubber on the outside. Balls inside are white idicating Zr base. Cage is translucent brown of unknown composition but seems OK for now. Will see if the red bearing grease I applied begins eating the cage over time. Research indicates I can expect at least 3x the life out of these over steel in the little dishwasher, and considering the Japanese 608z steel only lasted 18 months that equated to, at best, 120 hours of continuous runtime, seems pretty weak to me for an expernsive part that's so important to this household. Will install this in the dishwasher and follow up in about 6 months if this listing still exists. So far, I am very impressed considering the target market is basically fidget spinners and I can't find a single video of a person press fitting a ceramic bearing to fix any kind of motor, but it went very smoothly. So far: Thanks for making a good bearing with decent toleranced.

These come dry and have a rattle to them but after adding a couple drops of Krytox GPL 102 they free spin completely silently and roll like a dream. It's great that they come dry cause then you don't have to take them apart or clean out any grease - just pop the cover and add a couple drops and you're ready to skate. There are similar hybrid ceramics that come oiled but they cost twice as much and who knows what oil they used. EDIT: after about a month skating these I managed to crack a ball - deducting one star. The others are still rolling smooth!