Originally Posted by
chaadster
I don't agree with this at all, because watts are very easy to understand; the numbers are not meaningless, but rather the most accurate and meaningful way we have of quantifying work. Therefore, even if you don't plan to train to a specific goal, the power numbers will still tell the truth about your effort, and whether you were going as hard or as easy as you thought (i.e. watts vs. RPE). Without power, you could come back from a ride thinking you had a good, hard ride, when in fact (due to exhaustion, nutrition, or whatever) your actual output was under what you normally do (perhaps despite a similar HR). Power would reveal that, and even without a plan, you could say, "Hey, that wasn't up to par; why?" and make adjustments from there.
The metrics generated from a PM
initially may have very little value to someone such as the OP who admits that he's an average cyclist who wants to learn more about training and fitness. Especially if he plans to just use the PM to evaluate his actual output in relation to HR (or average speed) of his last ride as you suggest; not money well spent. However, as I said before, if his goal is to train for certain events, or just get faster for his everyday riding, it could be a great tool. If he takes the time and dedication to learn the software and what all the metrics mean, determine his FTP, etc., etc., then it could be a valuable investment. Seems like a lot of money, time and energy just to tell you that your numbers weren't up to par on a group ride. And to get them back up to par, what adjusts do you plan to make? Training plan and intervals which is were this began.