Originally Posted by jpr95 .
Perceived effort, heart rate and cadence are your available metrics. Speed is meaningless, save for overall progress if you regularly ride the same course in similar weather conditions (and small changes are still meaningless--only major time/pace/speed differences tell you of improvements or regression).
+1, with RPE and HR being the two big metrics for how hard you're working.
Personally if I was starting from scratch and a power meter was not in the budget I'd train by RPE with particular emphasis on breathing:
- On easy long days you should hardly notice your breathing at all and could hold a conversation at will.
- On Tempo days you should notice your breathing, it should be moderately deep but steady and you could still talk to folks but perhaps a bit haltingly and not in long winded sentences. You should be able to sustain this sort of pacing for long periods if you have the open roads or long climbs so it's not so hard that you're getting exhausted but you're still riding quickly at your own best 'fast fun pace'. This is typically a fun zone to train in as you roll along at a pretty good clip but it's still totally within your personal capabilities and you're not really suffering.
- On Threshold days where you try to sustain 15, 20 or 30 to 60 minute hard but sub-maximal intervals your breathing should be very deep, conversation would be limited to a word or two here and there but breathing is still controllable and not ragged or gasping. But this is about as hard as you can ride and still have controlled deep breathing.
- Move it up to VO2 Max pace for 3 to 6 minute maximal intervals and after the first minute and a half or so breathing will be maximal, no conversation is possible and you will be gasping by the end of each of these.
- Pretty much the same for really short hard efforts except the ragged maximal breathing comes on much sooner and then with full out sprints they're so short the maximal breathing happens after you shut down after ten to fifteen seconds of all out effort.
I'd use those guidelines with attention to the durations for each training level (e.g 15 to 60 minutes for classic Threshold work, up to a couple or more hours for Tempo work, as long as you have the time, motivation and saddle tolerance for long endurance work) and not get caught up in HR based training.
And that's coming from someone who trained religiously with HR for a couple of decades and worked with coaches who prescribed tight HR based training targets. Switching to power based training showed how often I under trained and how rarely I really did solid rides when I was spending so much time trying to stay in tight HR zones instead of just riding solid efforts for appropriate durations. If I had those years back I'd do as the old timers tried to tell me when I first started racing and before HR monitors first appeared on the scene and just ride my bike, ride fast on my fast days and ride hard intervals for preset times regardless of how my heart responded during those efforts.
-Dave