Accurate record of elevation gain does matter, since you may want to compare yourself to the pros. I use http://ridewithgps.com/ It's easy to use, free, and has a cue sheet print out. Checking against the barometric altimetry of my Sigma ROX 9.0 recorded at 5 sec intervals, this program agrees within +/- 16 feet over a 3.4 mile climb.

Ultimately you would want to convert to metric and figure your VAM, vertical ascent per meter, and finally your relative power output in watts per kilogram. The only additional info you need is a stopwatch to clock your climb time. Use this link http://www.cyclingfitness.net/what-i...-calculate-it/ to see if you're anywhere close to Contador and the gang.