SKF tapered roller bearings sphericalrollerbearing.com have the logarithmic contact profile that provides optimum stress distribution over the roller/raceway contacts in automotive bearings.In addition, highly accurate manufacturing processes make adjustment of the bearings against each other more reliable, which dramatically improves performance especially during the very first hours of operation.Facts About Skateboard BearingsPrecise bearings are great for high speed.Flag this photoIf you're interested in getting some new bearings, you might want to brush up on your knowledge of them. What Does ABEC Mean?The Annular Bearing Engineering Committee or Council (ABEC) of the American Bearing Manufacturers Association (ABMA) developed a system meant to rate ball-bearings against a standardized scale of precision.ABEC ScaleThe ABEC scale includes odd numbers between 1 and 9, where one is the least precise bearing, and 9 is the most. 

The higher the number, the tighter the bearing, meaning that the bearing is less tolerant to varying measurements during the manufacturing process. In general, a tighter bearing is generally more expensive than it's less-precise counterpart.Skate RatedSome skateboard bearings, like Bones timkenBearings, aren't ABEC rated, since this scale isn't intended to be the sole criteria for selecting bearings for highly specialized applications. According to the Bones Bearings website, "the ABEC rating system ignores side loading, impact resistance, materials selection and grade, appropriateness of lubrication, ball retainer type, grade of ball, the clearance between the balls and the races, installation requirements, and the need for maintenance and cleaning."The International Organization for Standardization (ISO)The International Organization for Standardization also has a scale for rating bearings called the ISO scale. The levels of precision are comparable to the levels of the ABEC scale, in the following way: ISO Normal, ISO Class 6, ISO Class 5, ISO Class 4 and ISO Class 2 are equivalent to ABEC 1,3,5,7 and 9, respectively.The German National Standards Organization (DIN)According to the DIN system, bearings are rated as either DIN: P0, P6, P5, P4 or P2. These figures align with the five incremental tiers of both the ABEC and the ISO scales.

Wheels W/ "Abec Bearings" for RAZOR SCOOTERS 100mm RED Includes 2 Wheels with Abec 7 Bearings. Diameter: 100mm. Durometer: 88a. Bearings: Abec 7 Rubber Shield Servicable. These high-performance, high-rebound scooter wheels were formulated specifically for street scooters. The 7-Star hub is designed to maintain strength & integrity of the wheel for riders who attempt extreme moves. Replacement wheels fit all 100mm type mini-scooters with and without suspension. Each bearing had dual rubber shields to protect the bearing from dust and other contaminates. The Shields are removable for routine servicing.