Roll-Line Devil FreeStyle Roller Skate Wheels (Set Of 8, 57mm)

You need 8 wheels for a pair of roller skates (2 x 4 packs or 1 x 8 pack)

DEVIL 36D, 39D, & 42D – 57mm Professional Injection FreeStyle Wheels

Hardness:  Ivory=36D, Aqua=39D, & Light Blue=42D
Diameter:  57mm
Compound:   A NEW Roll-Line patented-Mixed Compound Elastomeric Formula

The Roll-Line DEVIL 57mm Professional FreeStyle Wheels represent completely NEW design in the Patented Mixed Compound Elastomeric Formula and the start of a whole new class of Wheels.  This very high quality wheel, is designed to be used on many types of extremely slippery skating surfaces including standard wood floors coated with plastic or poly urethane, but also unusual surfaces like, tile type basketball and volleyball courts, tennis courts (Indoor or outdoor), and concrete or terrazzo surfaces that are more common around the World. The DEVIL 57mm Professional FreeStyle Wheels are used a great deal internationally, where there are few indoor skating centers like there are here in the USA. 

The Roll-Line Devil 57mm Professional FreeStyle Wheels utilize a stiff Delrin hub which is Strong, Light, and with Close Tolerances for Roundness, Trueness, and for the Cage where the Bearings and Spacers are mounted. The Roll-Line Tread is a NEW Patented Injection Molded secret Mix of Elastomeric Materials Formula, which provides ultra-strong Grip, even landing on the outer edge of the wheel, while providing great ROLL with a “Noiseless Effect”.
The Roll-Line DEVIL 57mm Professional FreeStyle Wheels have a little more feeling of spring or bounce as they have a higher REBOUND than most other Roll-Line Thermo-Plastiche and Urethane wheels (except the Helium Wheels).  This REBOUND creates a feeling of smoothness to the roll on the floor.  The Roll-Line DEVIL 57mm Professional FreeStyle Wheels has a small profile width.

The tread color identifies which hardness the wheels are.
36D = Ivory,
39D = Aqua, & 
42D = Light Blue

See the Picture for a DEVIL Comparison Chart

The softer the wheel, or lower Shore “D” hardness number, the more the grip and slightly less roll. The harder the wheel, or higher Shore “D” number, the more the roll, with slightly less grip.  The Shore “D” scale is used for Rubber and Plastics, while the Shore “A” scale is used for Urethane.

It is almost always recommended to use spacers in the wheels, when using standard 7mm bearings. Long ago, before the use of Lock Nuts (the nuts that have the Nylon Plastic inserts) to hold the wheels on the axles, Jam Nuts were used, but when the spacer was not as wide as the web of the wheel, or the wheel was not machined accurately, the bearings would lock up, the nut had to be tight, and could not be “backed-off”. This method, of locking the Axle Nut down, did promote proper bearing alignment and did increase the diameter of the axle from 7mm to approximately 14mm, because everything was locked down, which also saved the problems of bent axles. Today we do use Lock Nuts. It is still very advisable to lock everything down (especially for FreeStyle, Jam, and Roller Derby Skaters). Roll-Line does provide Spacers for Roll-Line Wheels with each pair of Frames or they can be purchased separately. Properly locking the Wheels down when using standard bearing types, will also promote longer bearing life.

The Roll-Line 7mm SpeedRace & SpeedMax Bearings , are specifically made for very High Level Competitive FreeStyle Roller Skating and are a very Durable Bearing with lots of ROLL. The SpeedRace & SpeedMax  Bearings are Free Rolling with minimal Radial Play which promotes and very evenly distributes the load across the 7 or 8 (of the SpeedMax) balls for optimal Roll and a good amount of Axial Play or Thrust, which is the side movement of the inner race in relation to the outer race. This movement is very important because when Skaters push, we always put side load on the skate to get power in the push or stroke. If the Bearing does not allow for this, it will bind and LOOSE operating speed or ROLL. These provisions in the Race Curvature and Contact Angle allow the Roll-Line SpeedRace & SpeedMax Bearings to ROLL very freely 

The Roll-Line SpeedRace Bearings have 7 balls and a rubber sealant Shield and the SpeedMax have 8 balls and a metal Shield and are ONLY available for 7mm Axles. The Roll-Line SpeedRace & SpeedMax Bearings are skated on by most of the World level FreeStyle Skaters and Champions.