The meat and potatoes of an inline skate are its boot and frame, colorless, staid components of the whole. Wheels, on the other hand, are sugar and spice, sweet orbs of colorful motion that indulge us in ever-changing scenery, the very eye candy which gives us cause to skate. Fresh out of the package and flashed with grease, these shiny little propulsion units look good enough to eat.

If you chomp on a wheel you'll notice that the urethane gives a bit. Some wheels are so soft they could be gummy bears, while others are so hard they could be Jolly Ranchers. There are advantages and tradeoffs to both kinds. Just as hard candy can jiggle fillings loose, so can a hard wheel rattle your bones. But if you skate an even surface, like velvety-smooth asphalt or polished concrete, a hard wheel will make you scream faster.

Hard wheels slide more readily, too. In some cases, less grip, or bite, is a desirable thing -- such as in a controlled maneuver like a slide (while turning, if you angle your forward skate's wheels to the point where they start losing traction with the ground and then flip the back skate around 180 degrees, you're actually scrubbing your speed with what's called a powerslide).

If you can imagine having superballs for skate wheels, then that's what it's like to skate on a wheel of 74 or 78 durometer. The first thing you'll notice is the rebound effect. It feels as if the wheel is actually giving energy back to you, and in fact, if you think about it, it is. A weighted wheel in contact with the ground surface is slightly squished and storing energy. When rolling, the wheel compresses on its leading edge and then decompresses on the trailing edge. This elastic rebound of the urethane acts like a spring, propelling you onward.

A soft wheel gives the best overall ride. Forget about fillings rattling loose: the soft compound delivers a forgiving ride that'll put a smile on your face as the scenery blows by. Because of its good bite, a soft wheel also corners far better than a hard one. You can push a softie almost infinitely hard without it sliding out on you. One drawback: just as soft candy doesn't last as long in the mouth as the hard kind, so do soft wheels get chewed up faster than hard ones. That's why for frugal skaters, harder 82A or even 85A durometer wheels are da kine because they take forever to wear down.

In some cases, too much of a good thing can be a handicap. If your wheels are all soft, you'll soak up all the bumps on the road, but a powerslide is so difficult that you may twist an ankle attempting one. On hard wheels, you'll be able to execute a powerslide without any problems, but your progress will be uncomfortably slow if the pavement you're on is not mirror-smooth.

Many times I want a combination of the qualities that hard and soft have to offer. Mixed wheels, like a chocolate sampler, is the happy medium that can give you the best of all possible worlds. On my recreational skates, I use alternating hard and soft wheels for a smooth, fast ride that gives me stopping power. The soft wheels grab the road whereas the harder ones glide faster and allow me to powerslide if I need to.

If I'm planning on spending three hours or more training on my racing skates, I choose comfort over performance every time, and set them up with the softest wheel combination possible. Because I tend to keep most of my weight over the rear wheels, I put the most comfortable 74A wheels in the back two spots, and fill in the rest with 78A's. This gives me a sweet ride every time.

For optimum speed on racing skates, my rule of thumb is easy: put harder wheels in positions of greater wear and softer ones in positions of less wear. I put hard wheels in back because I have a chronic tendency to push too much with my heel. By having harder wheels in back, I'm evening out the wear of all the wheels in relation to each other. This way I end up having to rotate them less often.

When racing, the best policy is always to survey the course before making a wheel selection, but you can virtually never go wrong if you combine durometers. For a mostly smooth course, 3 hard wheels and 2 softer ones intermixed is a prudent selection. For pavement that is slightly coarser but not yet rough, 3 soft wheels and 2 harder ones should perform admirably.

It's up to you to determine whether you want to skate on Jolly Ranchers or on gummy bears, or a combination thereof. Given the reality that to skate fast you need hard wheels, to use hard wheels you need good pavement and to skate on good pavement you really have to shop around an awful lot, I recommend opting for a mixed bag of wheels to handle various road conditions as they arise. Then, no matter where you may be, you'll always be on your own little patch of paradise.