Any pro (other than ) or coach you ask will tell you the importance of measuring performance on the bike. There are hoards of articles, books, seminars, webinars, and real live people that will tell you all about the many aspects of training. There are top secret methods that only top level athletes get to use. Only recently has Allen Lim exposed and explained a few of his on and off the bike strategies, and popular cycling websites have documented some extreme measures being taken during the grand tours.
The thing is, you don't need to drop thousands of dollars on a human-sized -150° C cyrotherapy chambers or space boots to have your hands on the most important performance tool. In fact, the most well kept training secrets (other than the white lunch bags) involve parameters measured, displayed, or analyzed by a cycling computer. My favorite is the Garmin Edge 500. To avoid going into full-on, gushy fanboy mode, I've highlighted a few of my favorite things about it.
- It's super minimal. Setup is quick - you can take it out of the box and be out riding in twenty minutes. The system itself is very simple, with only one sensor for both speed and cadence. Heart rate and power also pair up quickly via ANT+, and all together, you can be out training and nobody has to know. Stealthy.
- The array of parameters that you can choose is awesome. And a bit overwhelming. There are 45 different data fields you can choose to track while riding (I just counted), including road gradient! Ever wonder why you suffer so much on that one stretch of BoFax? It's because the road kicks up to 9%. There are nine involving power, eleven for heart rate, and you can even track your vertical ascent rate. It's so customizable that no two riders' Garmin displays need to be the same (really, there are 2.34x10^36 possible permutations of three pages of eight data fields per screen given a bank of 45 unique fields).
- The post-ride analysis offered by Garmin Connect is top notch. The timeline allows you to compare speed, power, elevation, etc. during any point on the ride and view them all on one plot. The lap counter is also pretty neat; I use it to compare intervals in a set using cadence, speed, power, and heart rate averages and maximums. Strava.com is also a fun post-ride analysis tool.
The Garmin 500 is the best cycling-related purchase I've made in the past few years (ask anyone that works at Mike's Bikes in Sausalito, they got tired of hearing about it), and only comes in behind my S-Works road shoes and last year's Cannondale SuperSix as my favorite product ever used in my short time spent riding bikes.