Originally Posted by Iride01

Have you ever done a ride to determine your lactate threshold in the past? If so, do another using the same method and see what you come up with. If not, then do one so you can get a baseline to use to judge future things.

I like how Joe Friel talks about setting HR Zones. Notice that LTHR in the way he sets them doesn't care what your max HR is.
https://joefrielsblog.com/a-quick-gu...-setting-zone/
https://joefrielsblog.com/the-30-min...s-easy-really/
https://joefrielsblog.com/common-but...raining-terms/

LTHR isn't max HR though some claim it predicts what your max HR will be. It simply another of many ways to establish HR zones. LTHR pretty much the HR that when you exceed it, your muscles put out more lactate than your body can clear. Exceed it continuously and eventually you just get stove up and bonk. Stay below that and you can ride for ever. Well not quite, but your body will eliminate the lactate quicker than your muscles can produce it so your muscles won't quit you when you need them most.

Still all the data you put up just suggests to me that your cardio vascular system is better than it was when you started as evidenced by better times and speed with less average HR. You simply just don't get near what your max HR might be as often.

If you want to find your max HR, then you need to pick a place to really go as hard as you possibly can for a very short time. This can be either a flat or a climb. I'd prefer a climb. But don't confuse this with determining LTHR as LTHR is the fastest steady HR you can manitain for a period. 20 minutes in J. Friel's method. Your max HR is simply how high can you get your HR. If you feel like puking afterward you might have gotten there.