How to choose multi-style roller skate bearings?

Professional Roller Skates Configuration

If you own a double or single row skating, skateboard bearing and you want to know its specific parameters, or how to open it for cleaning, please continue reading this guide.

At present, there are mainly 3 types of bearings used in roller skates, namely 627, 608 and 688. The 627 type bearings are mainly used for high-end figure roller skates and double row speed roller skates made in Italy; while the 608 type bearings are mainly used in the United States Manufactured inline skates and all inline skates and all skateboards and longboards; plus 688Mini bearings and 167 Mini bearings. The main difference between these three bearings is the diameter of the inner bore, indicated by the letter A in the figure below, followed by the type of guard, fixed or removable, and the precision of construction.

Outdoor Adult Two Color Roller Skates
A=627 bearing inner diameter is 7mm
A=167 bearing inner diameter is 7mm
A=608 bearing inner diameter is 8mm
A=688 bearing inner diameter is 8mm
B=22mm outer diameter (both for 627 and 608)
B=16mm outer diameter (for 688)
C= 7mm thick (for 627 and 608)
C= 5mm thick (for 688)
D = bearing code
E = ABEC ruler
G=outer ring
H = cage (metal or plastic)
I = gap
Note: In the early wooden wheel era, there was another bearing size with an inner hole diameter of 7mm, an outer diameter of 19mm, and a thickness of 6mm, which was installed on an old Italian 60s roller skates for women with a wooden wheel. To get back on this type of skate, you’ll need to replace the wheels and use 627 bearings, and equip yourself with M7 self-locking nuts instead of the classic M7 hex nuts.

Girls Outdoor Trend Roller Skates

Bearing code: 627, 608, 688

Bearing designation (D) Display number: 627, 608 or 688 followed by one or two Z. Z represents the dust cover. 1 Z means 1 dust cap, ZZ means 2 dust caps. Dust caps keep bearings clean from dust and water and are available in metal or black or colored rubber as shown. However, dirt will always manage to seep into the crevices indicated by the letter (I), so the bearings must be cleaned at some point.

ABEC specification

The ABEC specification is a system for classifying the build tolerances of precision bearings, which has been developed by the name of an American organization (AnularBearingEngineeringCommittee – Comitato ingegneristico per i cuscinetti anulari). The space (L) refers to the two slides between the balls (F) and in the outer and inner rings of the bearing, the smaller the space, the more precise and smooth the bearing will be. You might think that the higher the number indicated, the faster you can achieve, this theory is only true if you are using the bearing in a working machine that runs at 20000 rpm. In addition, especially in road use and after repeated T-stops or power stops, the bearing tolerances are reduced as the balls rub the rails to make a small section wider, so that ABEC-9 becomes 5, -3, -1, etc. In gliding, the speed you can achieve is just a matter of your legs. However, ABEC scales exist, and are: ABEC-1, ABEC-3, ABEC-5, ABEC-7, ABEC-9, ABEC-11, most commonly -5 and -7

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