The wheel spacer is a part located between the bearings inside the wheel, and is responsible for its proper wheel spin.
By tightening the wheels, side walls of a frame are getting very tight which guarantee bearing to stay in their permanent position and proper spinning. Spacer mounted in a wheel, is responsible for maintaining an optimal distance between the bearings even with a very strong screw tightening.
Lack of spacers in a wheel causes way too strong emphasis on a core , resulting in increasing problems with proper wheel spin.
Spacers are available in two sizes: 6 and 8 mm, both are suitable for all inline skating bearings.
Regardless of the size (608, 688, 668) and class (ABEC, ILQ etc) all bearings for inline skating have the same diameter of the screw hole: 8mm.
Depending on the diameter of the screws in the frame, wheels will need 6 or 8 mm spacers.
8mm spacers are mounted freely between the bearings. Mounting bolt passes directly through the opening in the bearing, and then through the spacer.
6mm spacers have special tabs inserted into the placenta, which reduces the diameter of the hole from 8 to 6mm. Mounting screw in this case passes through the entire length of the spacer.
Again, we emphasize that all bearings have the same diameter of the screw hole, and before buying new spacers one should check the size of screw rings. If the original wheels were mounted with 6mm spacers, you should buy new 6mm spacers too or if the state allows it, use the original parts.
NOTE: You do not need to measure the diameter of the spacers in order to assess its size: spacers freely mounted between the bearings have always 8mm and spacers with insets are 6mm.
When you buy spacers, pay attention to the design of the core circle. Most of the wheels on the market is designed to mount 8mm spacers that facilitates the centering of the mounting axle. However, there are models which the core is able to accommodate only the spacer of 6 mm.
Width of the core in the wheels is in most cases the same. Differences in width using standard spacersare undetectable in normal skating.
In time, it is worth paying attention to the state of spacers that can reduce its width - thus tighten the bearings on the core wheels and increase the rolling resistance.
Professional skaters who want to exploit the full potential of their wheels and bearings, benefit from a dedicated spacers to a specific model of wheels. Their width is exactly the same (accurate to 0.01 cm) as the width of the core.
Replacing the bearings should go hand in hand with the exchange spacers to maximize the potential of the new equipment.