Sizing Get fitted at a shop with technicians who use stationary trainers to evaluate your body in motion. Don't take advice from anyone relying on only mathematical formulas. "The key is to make the bike fit the rider," says Pruitt.

Shoes Sit on a table with your legs dangling. Note how the outsides of your feet hang lower than the insides. "That's called forefoot varus," says Pruitt, "and 90 percent of people have it." Most shoes fail to take this into account. Buy wedges that slide inside the shoe or under the cleat to maintain the foot's natural cant. OUR PICK: The Wedge, $25; bikefit.com

Saddles "Find a saddle with a flat top that supports the sit bones and has a cutout," says Pruitt. Saddles come in different widths, so buy one that best supports your sit bones; it will reduce pressure on tender areas. OUR PICK: Specialized's Toupe Saddle, $145; specialized.com

What's in your frame?
A quick, authoritative review of the most common bike-building materials
Steel: Cheap and buttery smooth on the road but also heavy and prone to rust. Popular with traditionalists. $

Aluminum: Relatively cheap and incredibly stiff, which means efficient pedaling but also a slightly harsh feel on the road. $$

Titanium: Light, rust-proof, and extremely durable. It provides a ride quality similar to that of steel, but the cost is much higher. Primarily found in boutique and custom bikes. $$$$

Carbon Fiber (as shown in the new Parlee Z4, $3,200; parleecycles.com): The material of choice in nearly all top-end frames, with an amazing strength-to-weight ratio. It can be easily manipulated into different shapes to deliver countless variations in ride quality. The one caveat, beyond expense: If it cracks, it's finished. $$$$