I have a garmin forerunner and use ascent to download the data. I have the HRM and cadence monitor. (Also works for any other activity as long as you are moving.)http://www.montebellosoftware.com/index.html

I have also used excel spreadsheets that I set up for whatever event I'm training for to keep track of mileage goals.

It can be that you spend more time tracking your miles etc than you do logging the actual miles. The Forerunner makes it easy.

sarah