Drew Eckhardt 

Aerobic and anaerobic threshold fractions of the maximum vary too much for it to be useful. Numbers from different sports also don't work because muscle recruitment and therefore your ability to use oxygen vary,

Ride as hard as you can for thirty minutes. Take your average heart rate over the last twenty. That's your anaerobic threshold (AnT, VT2, LTHR, LT4, lactate threshold).

Ride as hard as you can without breathing becoming rhythmic, feeling your legs, and conversation not flowing. That's about what you can manage for 5 hours with an even effort split between halves. That's your aerobic threshold (AeT, VT1).

Training above your anaerobic threshold does the most to increase VO2max and one hour power, noting heart rate is a lagging indicator. Just ride as hard as you can for 7-10 minutes and stop when you can't break get past it by the end of an interval. One day a week is plenty. Longer intervals don't stress you enough, shorter limit total time because fatigue is proportional to the square of effort.

Training below your aerobic threshold does the most to increase performance over longer durations. Mark Allen set his unmatched 2:40 Ironman marathon split record in 1989 after training below his aerobic threshold, initially dropping his pace to 8:15 miles with performance improving over a year to 5:20 at the same 155 bpm heart rate. Exceeding it produces a shift in muscle fiber recruitment and energy substrate utilization for the rest of your ride.

Far above your anaerobic threshold you have neuromuscular power using the creatine phosphate energy system which isn't good for a full minute.

Far below your aerobic threshold is fine for active recovery if you don't want unsatisfyingly short rides during rest periods.

Between the two you have fun rides and perhaps racing.