Ask The Coach - Wheels & Bearings

Wheels & Bearings
Vocabulary Terms Selecting a Durometer Selecting a Diameter Comparing Core Types Selecting a Wheel Profile Rotating Your Wheels Bearings	Welcome to "Ask the Coach!"
About Inline Wheels Before we start covering this topic, let's make sure you're up to par on a few key terms and the basic knowledge necessary in determining when and how to buy a new set of wheels. Choosing wheels varies based on what type of skater you are, so know a little about your style before we get started.	Coach says, "I'll help you make an informed purchase."
Vocabulary Terms Durometer is the measured hardness of the wheel. This is denoted by the "A" number, where the larger the number, the harder the wheel (on a scale of 1 to 100). Most wheels on the market are 78 or 82A durometer. The harder the wheel, the longer it lasts, but also the less it absorbs shock and vibrations from your skating. Softer wheels tend to provide more grip and absorb more vibration. Unfortunately, all good things come to an end... So the softer the wheels, the faster they will wear down. Diameter is the height of the wheel, measured in millimeters (mm). Most wheels are 70mm, 72mm, 76mm, or 80mm, the major exception being aggressive skating wheels, which are often in the low 60s and may go as low as 57mm. In general, given the same conditions, the taller the wheel, the faster you can skate. The core contains the hub and spokes of the wheel. The hub houses the bearings and bearing spacer (where the axle goes through); the spokes and outer hub bond to the wheel material itself (the polyurethane). Core designs range from solid (no spokes) in aggressive wheels, to super-light spoked designs in racing wheels. The profile is the cross-section of a wheel (looking head on). The profile curve determines how much of the wheel contacts the skating surface at any given time. The durometer and diameter will have the biggest effect on your skating, so you should base your wheel choice based on those factors first. Cores and profiles have significant, but more subtle consequences, so you can compare them after you've figured out the durometer and diameter.

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Selecting A Durometer

One important thing to keep in mind is that you are not required to use the same durometer on all your wheels. Many skaters use mixed durometers to achieve a more desirable blend of grip, shock-absorption, and durability than is possible with a single durometer setup. At first it's hard to know what mix to use, but here are some things to look at:

Wear patterns

Before you rotate your wheels during your routine maintenance, note the wear pattern on the wheels. Do any wheels tend to wear a lot more than the others? If so, you might want to put harder wheels in those positions. For example, I tend to wear my rear wheels more than the others, so use 78A's in the front two positions, and 82A's in the back.

Durability and shock-absorption

You may find your wheels wear down faster than you'd like because you skate on rough surfaces. You could opt to buy all harder wheels, but it might give you a pretty rough ride. One alternative is to replace only half of your wheels with a harder durometer, like half 78A's and half 82A's. The order that you put them in, isn't really that crucial (although I would suggest 78,82,78,82, or 82,78,78,82). What this mix gives you is the shock-absorption of 78A's and the durability of 82A's.

Skating style

Speed skaters and aggressive skaters are the ones who use mixed durometers the most. Speed skaters do it for the hybrid durability and shock-absorption mentioned previously. Aggressive skaters often use the anti-rocker setup where the middle two wheels are very short and hard, and the front and back wheels are tall, to make rail slides easier.

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Selecting A Diameter

Okay, had enough of durometer talk? With the wheel diameter there isn't a whole lot to consider. Most recreational skaters prefer the tallest wheels they can fit on their skates (typically 76mm on middle-range skates, and 76-82mm on high-end skates). Taller wheels means more speed and the wheels last longer than shorter wheels of the same durometer.

Aggressive skaters will obviously favor shorter wheels, possibly even wheels under 60mm, to give room for grinds and slides, and also to keep their skates closer to the ground (or whatever is being skated upon).

Hockey players may opt for a Hi-Lo system using two different size wheels to allow faster take-offs and sharper/faster turns.

Speed skaters usually go for the tallest wheels in the 80 to 82mm range. However, this varies depending on the race situation. For example in sprint races, 76mm may be more appropriate.

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Comparing Core Types

Cores can vary significantly in design. On race wheels, the core may incorporate spokes, and comprise a large portion of the wheel. This is meant to lighten the wheel, and provide cooling for the bearings. A larger core will make the wheel lighter, but that means there is less polyurethane on the wheel to wear down. If speed is the top priority, then that shouldn't matter. If durability is more of an issue, then you may not want wheels with extra large cores.

Cores are usually made of nylon type materials similar to the material that make up the runners and boots of your skates. Some cores are now being made of aluminum, but most are still made of plastic. In the past, some wheels have suffered problems in the core, where the core loosens from the polyurethane. However, this hasn't been as much of a problem recently, due to improved bonding technology that binds the core to the wheel.

In general, there's not too much to worry about in the core. The main exception is if you do lots of jumping. There have been cases in the past where the spokes on the wheel fracture and then collapse after extended periods of stress. This is more the exception than the rule, but you may look for a sturdier core if you think you might crush your wheels.

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Selecting A Wheel Profile

In general, hockey wheels, recreational wheels, and speed wheels are somewhat interchangeable. That is, you can use any of those wheel types for any of those skating activities. You won't get optimal performance, but you won't have to swap wheels every time you switch activities either.

However, if you're looking for the best results, you may want to look at wheels designed for your type of skating. In the following diagram (drawn approximately to scale):

You'll notice that:

Recreational wheels have average height, average taper.
Speed wheels are taller, thinner, more tapered.
Hockey wheels are shorter, wider, rounded.
Aggressive wheels are short, with a wide, rounded profile. Often they are very short and have a solid core.

Eventually any type of wheel will wear down to the point where the original profile is lost. There's no way around that unfortunately. Whether you replace your wheels then, or not, is up to you. For most people, the profile only makes a subtle difference, so unless you're in a highly competitive skating situation, I'd just use the wheels until they're worn all the way down.

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Rotating Your Wheels

There are several methods to rotate your wheels, some involving using a caliper to measure wheel size and recording it all on a data sheet. The truth is, who cares about a data sheet, anyway. We've found this to be the simplest method of wheel rotation:

Move the wheels from one skate to the other.
Put the largest wheels in the front and back positions.
If you wear out your wheels faster on the inside edge, flip each wheel so the most worn-out edge faces out.

Freshly rotated wheels can feel a bit strange when you skate on them and it can be difficult to keep your balance. This problem can be reduced by rotating your wheels frequently, and by rotating the largest wheels to the front and back positions. If you your wheels do feel strange after rotating, they will feel normal again after a few days of hard skating.

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Bearings

For the last decade, skaters have grown accustomed to standard bearings rated by the ABEC bearing system. Now, new technology has allowed the advancement of bearings into a lighter weight, more efficient bearing called the microbearing. These bearings are smaller, and 60% of standard bearing weight. If you buy skates requiring microbearings, they can only be replaced by microbearings and the wheels that use them.

ABEC bearings are rated from 1 to 9. These numbers represent the level of tolerance used when manufacturing the bearing. "Tolerance" is the variation allowed during the manufacturing process. So, the higher the ABEC rating, the more care taken to produce them, the more out-of-pocket cost. Also, a higher rating doesn't necessarily mean a faster wheel, but there is a significant difference between an ABEC-1 and an ABEC-7.

Care and Maintenance

Bearings need to be serviced when needed. Build up of contaminates and dirt will hinder your mobility. Serviceable bearings have a removable outer ring and can be degreased and relubricated. Non-serviceable bearings should be wiped clean with a dry cloth. NEVER lubricate the outside of the bearing, because this only attracts dirt and other contaminates.

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