Its a common feeling I suspect, a lot seems to be psychological to me , like a lot of things in cycling the desire to get home or just the relief of nearly there, gives you new motivation or takes your mind of negatives that were holding you back.
Where I could be wrong I think the body holds something in reserve in most people as they can’t push hard enough to burn it off (even though it psychologically feels like theres nothing there) but those that excel in TTs etc, get it all out on the road and there’s no second wind for them.
I just wondered this few days ago. Did 2x60min tempo on a long ride, the second effort started to feel a bit tough in the end. Kept riding and did a 3rd hour of tempo which felt almost like Z2, effortless.
I’ve noticed this happens to me often after I’ve done my intervals and decide to do some extra, the extra ones feel really easy.
You always get this on a long ride. Let’s say you’ve been riding 10 hours and you feel done in. You then get within an hour of finishing and you can up the tempo as you know you’ve only got to do it for another hour. I think most of us hold something in reserve for the duration / efforts we are expending then tap into that reserve when we feel it will now last us to the finish.
low intensity very long duration rides (10h+): mood/motivation changes throughout ride but there is always enough strength to go on (although sprints can be very laughable efforts)
long Z3/SS interval (a la 1x90min+, with no rest periods): only then I can achieve this euphoric feeling with sense of complete freedom and endless power. And actually even have sufficient power to push 5min at 110%. Haven’t tried past 1x120min, though, can’t tell how long it may last.
I Heard someone say when this happens you are getting close to bonking. Eat something was the thought. I have had this feeling. Feels great. Usually only allow it at the end of the ride. Usually after some previous higher volume. Is it just extra blood volume. Good news is I can replicate it now with planning. So far. Happy cycling