This is a pretty good summary of Aerobic base training and heart rate caps by Mark Allen
READ...this is some of the best pre-season advice I have ever read.

http://www.markallenonline.com/Base.asp

This is how I calculate my estimated Aerobic Cap, a little different than Allen. This is how I learned from some good Cardiologist Athletes while in Med. School in Florida

Take 220 and subtract your age
From this number, subtract your waking, resting HR
From this number, multiple by 0.7 (70 %)
Now, to this new number, add back your resting HR value.
This final number is very close to your Aerobic cap.

Example: My age is 41, my resting HR this morning was 46
220 - 41 = 179
179 - 46 = 133
133 X .7 = 93
93 + 46 = 139
So, virtually every ride and run should never go above 139 for me. At least for the first 8-12 weeks. Hill rides are ok...you just have to slow cadence and work on muscular endurance.
Your estimated Anearobic threshold (not aerobic) uses the same formula, but instead of multiplying by .7 (70%), you multiply by .80 (80%) which will be very close to your threshold (Zone 5a using Joe friel's "going long" book to calculate) Using this method and resting HR of 36 last spring, I calculated 150 as my Zone 5. Well, using treadmill to calculate my true max last spring, then using Joe Friel's methods, HE came up with 149 for my top of zone 4, so, 150 would be zone 5....amazing. This is the reason I trust Friel's HR and zone estimates, and why I use them.

Now, Mark Allen's method for aerobic cap:
180 - age
subtract 5 beats from this number if freshly starting
subtract 3 beats if workouts 2-3 times per week
If you workout 5-6 X per week, leave alone
If you workout 7 or more times per week for a year, add 5 beats.

So, for me, I say 5-7 days per week as I am starting up again:
180 - 41 = 139
139...and my own calculation is also 139.

Now, how does MY number change? The only changing variable is my resting HR and age. My resting HR will be down to 32-36 by mid January. Using 36 as my new resting HR (because I will be getting into better shape) the new calculated Aerobic cap for me will be 136

How does this tie in to Allen's calculation? Well by mid January I will be doing 7-10 workouts per week. Thus I have to add 5 beats to his formula of 180 - age. Allen's new number for me is 144.
Try it yourself...I am interested in how close your "scientific calculation" comes to Allen's "quick calculation. Using Allen's quick calculation, there IS a difference between my 136 and his 144. Your HR caps at the aerobic and anaerobic ends should decrease as you get more in shape. Not a large amount, but by 3-5 beats. This doesnt make much difference on the low end, ie: the aerobic cap. But, for doing Zone 5 or 5a work (sub-threshold and threshold) being 5 beats over your zone can lead to overtraining in several weeks.
So, I didnt originally catch the reasoning behind Allen's adding 5 beats if you workout 7 times or more per week, but I am not sure what to make of it. It is a good formula to start out with if working out in base zone for the first month or 2. Then as fitness improves, I think the best way is to manually calculate your max off the treadmill.

Calculating the max:
I like to have 4-6 weeks of base work first, primarily so I dont hurt myself.
Treadmill test:
Start in your zone 1 pace. Run 10 min warm up. Take a couple min. and lightly stretch if needed.
Then start by running 2-3 minutes at an easy pace, top of zone 1.
Start increasing the pace about 10-15 sec. per mile every minute.
After the first 30 seconds, start another 1 min. cycle by increasing the grade 0.5%
So every other 30 seconds, you are either increasing pace or grade.
Continue this until you literally have to step off the treadmill because of exhaustion.
Take 3-5 min. to lightly stretch and repeat. Take the higher of the 2 numbers.
This is your max. However, I have done this test in the winter, and raced a week later, usually 5K (back when I was a pure runner). When I did this, more than once, I could reach a max in race situation slightly higher than the treadmill, usually about 2-3 beats. I believe its just the energy of the race-situation.
So, after I get my max off the treadmill, I add 2 beats to the higher number, and use for my max. This seems to work well for me.
I typically start at 8 min pace and 0% grade. When exhausted, I am usually around 6:40 pace at around 5 % grade. Each of the 2 tests should not take more than 8-10 minutes. If the first test took you more than this, then you started out too slow. Simply start out at a faster initial pace than the first test if this occurs. Estimate it. If it took you 12 minutes for the first test, you only have to start about 30 seconds faster from the first test. If it takes you 15 minutes, then you probably are starting out far too slow. If the test takes you only 6 minutes...you started out too fast.
Dont worry if you aerobic cap is not exact to Friels' method. Friel has 4 zones before the anearobic threshold. So, Friels zone 1 is not the aerobic cap, its Recovery. I think zones 1, 2 and probably half of zone 3 would still be highly purely aerobic in Friels book. Top of zone 3 and zone 4 are getting into sub-threshold pace. Sub threshold work is not purely aerobic, and be careful training in these zones for longer than 10 % of any workout greater than 12-16 weeks out from the key race.