What is a 'bore' in skating?
In mechanics, a bore is an operation that consists in machining the inside of a cylinder. By extension, the word 'bore' is used to refer to inside diameters.
And in skating?
In skating, the word 'bore' refers, somewhat imprecisely, to the center hole of bearings or spacers.
Some spacers are inserted into the bearings
In skating, there are essentially bearing with bores of 7 or 8 mm. There are also spacers the bore of which is of 6 mm to enter the axles.
Bore diameters in skating
8 mm bores are commonplace in skating, for both spacers and bearings. The '8' in the '608' designation corresponds to the diameter of the center of the bearing. Most of the time, the bigger the axle, the most resistant it is. This diameter tends to become widespread.
In quad skating, 607 bearings (with a center hole of 7 mm) are still common. They can be found particularly in artistic skating, rink hockey and roller derby.
Some aggressive and fitness skates are still equipped with 7 mm axles, even 6 mm sometimes.
Most of the time, when an axle has a 6 mm diameter, it is completed by a long spacer that has a 6 mm bore and an outside diameter of 8 mm to get inserted into a 608 bearing...
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Translation: Chloe Seyres