Inline Speed Skating - Skate

Skate

An inline speed skate is a specialized shoe version of the inline skate. The boot or shoe is close-fitting, without much padding and usually made of leather and carbon fiber and/or fiberglass composites. For best performance, the boot must conform closely to the shape of the foot, so most inline speed skating boots are heat-moldable, which allows the user to re-shape the boots to some extent when heat is applied (by placing the boots in oven at 185 °F (85 °C) for 15 minutes after taking off the wheels, frames, and straps/buckles). It is also quite common to have boots custom-made, for improved fit.

Speed skating boots are low-cut and offer little ankle support, allowing the skater extra ankle movement. Skin blisters due to friction can be a problem, and common solutions include: neoprene or silicone "ankle bootee" such as "Ezeefit" or "Bunga Pads", double thin synthetic socks, smaller boots, improving technique, re-moulding the boots, sports tape, and use of "advanced healing" plasters to help recovery.

The frame (sometimes called the chassis or plate) which holds the wheels is made of aircraft-quality aluminum or magnesium. Frames flex during skating, and the amount of flex can be a personal factor in which one to choose. Very "stiff" frames are usually favoured by heavy skaters. A frame which is too stiff for a particular skater may feel unstable on corners, and a frame that is not stiff enough will be slower. Frame stiffness also works along with boot and wheel stiffness, so there are endless possible variations. A light frame is desirable. Ideal frame length is affected by foot size and wheel size. A slightly shorter frame is often preferred for the tight curves of smaller tracks.

The frame position can usually be adjusted with respect to the skate, to adjust for a skater's individual foot, ankle and leg characteristics. The frame usually mounts three, four, or five polyurethane wheels. The three wheel frames are used by skaters with small feet, otherwise 4 wheel frames are commonly used, with 90 mm to 110 mm diameter wheels. Five-wheel frames with smaller wheel have lost favor. Each wheel contains two ball bearings with an aluminum spacer, held in place with an axle screwed into the frame.

Larger wheels require better skating technique, so skaters generally progress upwards in wheel size as they gain experience. "Hi-Lo" arrangements are also available, which usually have three larger wheels and one smaller wheel under the ball of the foot, allowing a lower and shorter overall frame design.

Harder wheels minimize elastic hysteresis energy absorption, due to skater's weight deforming the solid polyurethane "tyre". So, speed skaters tend to select the hardest possible wheels, with the highest polyurethane durometer for their skating condition, limited by either wheel slip or surface roughness. Durometer selection is also affected by skater weight, and temperature. Wheels for indoor use are hardest with a durometer of 88–95. They tend to last well, but can be easily damaged if used outdoors. Wheels for outdoor use are softer with a durometer of 82–87, and tend to wear more quickly. Harder outdoor wheels can also be used effectively indoors. Skaters sometimes combine different hardness wheels on the same skate in an attempt to achieve the best combination.

Skaters also refer to wheel "rebound". This refers to the relative height to which a dropped wheel rebounds. It is a reasonable comparative indicator of the relative energy absorbed by elastic hysteresis of a wheel during skating.

Bearing sizes have been standardized around the popular 608 series. A smaller and lighter 688 series has had limited acceptance. Bearing manufacturing precision generally run from ABEC-1 to ABEC-9, and some skate bearings are additionally designed to be "loose" to minimize ball rolling friction.

Various grades of steel offer better hardness, rust resistance etc. Bearings with ceramic balls (and races) have been available since the late 1990s, They are lighter and longer lasting, however significantly more expensive. Black silicon nitride ceramic is superior to white zirconium dioxide ceramic, since it is considerably harder and tougher. At the modest rotational speeds encountered in skates, manufacturer data suggests negligible difference in friction performance between the various bearing materials. At these speeds, ball bearing friction tends to be dominated by seals and lubricants.

Bearing shields reduce the entry of dirt into the bearing. Metal and rubber non-contact shields are commonly used, of which rubber shields are slightly more effective. Neither shield type is totally effective, often resulting in the need for bearing maintenance. The ball retainer is usually made of either metal or plastic. Plastic types are preferred since they are quieter.

Bearing lubrication is usually either light oil or grease. Synthetic types last longer before breaking down. Grease assists in holding dirt away, and stays in the bearing longer, reducing maintenance and increasing bearing life. The lifetime of bearings used for outdoor speed skating is often quite limited due to damage caused by dirt ingress.

In search of the maximum speed the principal goal is to minimize wind resistance, hence the use of skinsuits, special helmets and techniques. The second issue is elastic hysteresis energy absorption in the wheel. The distant third is bearing internal friction, a set of bearings in good condition, properly inserted and lubricated is normally enough.