You've been riding since mid-'04, so I think it's safe to say you've got your 'base' and form down, good job! So no worries about pushing the HR, your body has safeguards that you're not gonna get around; like trying to hold your breathe until you pass out, it'll stop you before you hurt yourself. So you're not gonna be able to push the HR to the point of damage without your body making you quit.

First, you gotta find your true max-HR, I doubt 187 is really it. I suspect it's in the 190s, so do the stress-test on the bike and treadmill to find out. Then you'll be able to make some training plans based on that real-world number (the equation 220-age equation is often off by +/-20% ). Keep up the good work!