After looking at all the different types of bike computers, Ive narrowed it down to a Garmin. I've noticed alot of guys/gals use the Garmin Edge 305 over the Edge 205. Is there a reason why the Edge 305 is preferred over the 205. 205 is cheaper but the 305 has the heart rate monitor, cadence, and the elavation. Or is it just a preferrence and the cadence and monitor are more for a training aid? Any opinion would be great.