Leathers should be comfortable in a riding rather than standing position. Look for armor in the shoulders, elbows, hips and knees, and stretch panels on the backs of the knees and elbows as well as the lower back. Leathers can be a bit snugger than a street-riding outfit because you will rarely need extra clothes underneath-add layers over the leathers in cold weather. Additionally, speeds are higher on the track and any loose material will flap annoyingly.
What you wear on a bike may not help you to ride better, but improper gear can certainly spoil a street ride or slow you down on the track. Case in point: At last year's fall Daytona Moto-ST race, our man struggled with his bike's tank constantly battering his chest on the banking, distracting him and making it difficult to tuck in. A chest protector only made things worse. It turns out the rear bulge on the tank put pressure exactly on the zipper pull of his inner suit, which in turn pressed directly on his sternum. The solution? A tiny piece of cloth padding taped over the zipper pull. Sometimes the simplest details can make a big difference, and sometimes you may not even realize that a piece of loose or tight gear is causing you grief until you wear something that fits correctly. Here, then, are some guidelines to follow when selecting riding gear for the street or track; apparel that fits comfortably and provides ample protection, yet doesn't irritate or distract you.
The most important piece of riding gear is the helmet, from both safety and comfort standpoints. Choose a helmet that meets DOT standards and is approved by another entity such as Snell, ECE or BSI, and try different brands and models to find a lid that fits your head's shape as well as its size. Look for good peripheral vision if you do a lot of street riding. Helmet prices vary wildly, but it's worth paying extra for something that is lightweight, has good venting characteristics and has an optically clear shield that doesn't fog in cold weather. Wear a dark shield rather than sunglasses, as glasses can interfere with your peripheral vision. You can wear a thin balaclava underneath to help keep sweat out of your eyes and to add a layer of insulation, and a pair of earplugs will keep out wind noise, which protects your hearing.
Good-quality boots will have a mechanism to restrict side-to-side movement in the ankle yet allow easy fore-and-aft movement to operate the controls. Some boots do this externally, some internally. Boots should be tight enough that your foot doesn't move inside, and snug in that calf area whether you wear them outside or inside of your pants or leathers. | 
A good racing back protector will provide coverage right down to your tailbone and fit comfortably under a set of leathers. This may be too long under a jacket/pants combo for street riding in a more upright position; a shorter protector will fit under a jacket yet still provide good coverage. | 
For street riding, your jacket and pants should have ample protection in the elbows, shoulders, knees and hips. Choose either a one-piece suit or a jacket and pants combination that zips securely together; the outfit should be loose enough that you can fit a couple of extra thin layers underneath on a cool day, yet snug enough that nothing flaps in the wind. |
The most common mistake we see when people try on a jacket, pants or leathers is they stand upright to determine fit. When was the last time you rode your bike standing upright? Proper sport-riding gear has forward-rotated sleeves and stretch panels on the inside of the elbows and knees so that the material doesn't bunch up. Sit on your bike or crouch down to properly feel how the gear fits. A good street riding outfit will have padding in the elbows, shoulders, knees and often-overlooked hips, and you should have room underneath for a spine protector and additional clothing for insulation. Layer up for warmth rather than use one thick sweater; this will help avoid bunching and let you peel off layers as needed over the course of a day.
At the track, a good set of leathers has all the padding that a street suit has, and you should invest in a quality, full-length spine protector and a chest protector. If you doubt the benefit of a chest protector, ask the Geek about getting poked in the ribs by a ZX-10R key at the dragstrip. The suit should be snug enough that it doesn't flap in the wind yet loose enough that you can move around freely on your bike. A mesh inner suit will help with the latter, and you can replace that with a "wind-stopping" inner suit for colder days if you choose a suit with ventilating holes. Look for stretch panels in the backs of the knees and elbows as well as in the lower back area, and comfortable armor that doesn't dig in when you're in a riding position.