Any question answered...

Heart rate monitors. I've been reading about how they aid training. Mostly about Zone 2 rides to build an aeroic base or something.
I rode with one for the first time today, topped out at 187bpm, seem to have a resting bpm of 70 and over 30 miles averaging 150bpm when going 20mph. It was a fairly average ride, on a route I've done a good few times. Although I didn't feel particularly strong today. That puts my average bpm at 80% of max and apparently in "no-man's land"
Apparently if I were to ride at 120-140 bpm instead then it would raise my aerobic capacity and would be able to go faster for the same effort.
This sounds good to me, but I can't get past the feeling that riding slower for the same distance just isn't going to help. I don't get much time to cycle, usually just 1 or 2 days a week, so want to make the most of it.
Does anyone on here use or have used a HRM to train? Have you done the whole cycling in zone 2 thing and has it worked?

My info is based purely on reading a lot of books and one season of racing so don't take my words as the truth but my experience is:

Having read a few slevless and ironman training books, they recommend staying below Anaerobic Threshold (AT) to build up base fitness, then do interval training to boost speed. The interval training stretches your muscles to the point of 'damaging' them but then when they recover, they recover stronger, thus making you faster. The side effect is also that you raise your AT over time, thus allowing you to ride faster/harder without crossing the AT and so you can keep it going for longer. You can always replenish oxygen by breathing, but as soon as you go AT, you have a finite amount of muscle energy/strength without resting, so you'll end up burning out/blowing up/not being able to ride very fast any more. To compare the turtle and the hare, the hare sprints off above his AT, then knackers himself out, and limps home, whereas the turtle stays in zone 2 the whole time and crosses the line first. The books say if you don't stay in zone 2 after doing AT training, your muscles won't recover and repair so you won't see the benefit of your effort.

Used to.

Ride faster to go faster.

There's a HRM thread.

After reading Adam Topham's book, he basically says screw all that namby pamby recovery and zone 2 shit and just ride hard all the time as much as you can. What's the point in rolling around at 15 mph when you want to race at 25mph? Your body needs to get used to what you want to do, so if you're going to spend your time at 25 mph in the race, train like that.

It's sort of a build your strength for the race over time method versus keep smashing yourself over and over again and your body will get use to it method.

I utilised the zone 2 and intervals method over winter 2011/2012 and when I did my first race I didn't really feel prepared, I then spent the season just riding liking I was racing all the time and I got better over the course of the season, but then that could be that the 2nd method was better or that I was getting used to racing.

Too many variables, and too long a post from someone who knows too little.

TL;DR