“Even the companies that promote high-tech fitting services admit that the profession is still as much about nuance as it is about data points. Others in the industry simply call fitting an art form.”
(Andrew Tilin, Bicycling Magazine)
Though there has always much debate about exactly how to do it correctly, there is nearly universal agreement that correct (frame) sizing and some type of basic “fitting” of each rider to their specific bike is very important–and necessary to achieve maximum efficiency (and maximum comfort) on any bicycle.
Clearly, the more efficient you are, the farther and faster you can ride with the same amount of effort. And the more comfortable you are on your bicycle, the less prone you will be to injury–and the more likely you will be to ride at all. (When was the last time you got excited about spending 30 minutes, an hour, two hours, four hours, etc–doing something strenuous, in an uncomfortable position?)
The following are some web links to interesting articles that I run across from time to time about bike fitting in general. I recommend reading through them to educate yourself about the topic before deciding on whether to spend $40 or $50 at a local bike shop for a basic fit… or spending $200 to $700 on a more involved, elaborate, personal fitting with an “expert”.
http://www.bicycling.com/news/featured-stories/fit-fundamentals
http://www.jimlangley.net/crank/bikefit.html
http://www.bikefit.com/s-13-road-bikes.aspx
Serious / professional riders often take FIT to the next level by ordering custom built built frames that are designed for their exact / specific measurements–and their particular type of riding… then special ordering various other components (stems, handlebars, cranks, seat posts, saddles) for the most perfect fit possible. (As you can imagine, this can be a very expensive exercise–with fully built bikes costing well into the $10,000+ range.)
If you watch much bicycle racing you’ve seen how most races come down to the wire with margins of victory in the seconds rather than minutes… so, any competitive advantage–no matter how small–can be worth the expense to a pro cyclist… or even to a highly competitive amateur. But to the average rider, more / better training will have a more measurable effect than more expensive equipment.