Non-sarcastic tip:

Your heart rate is somewhat correlated to your cadence. Your legs help pump blood through their rhythmic contractions. Increasing the rate of the contractions seems to increase heart rate, even if you're putting out less power.

Note: correlation is NOT causal - so I don't know if a higher cadence causes higher heart rate. I just observe the two are related.

So let's take your hill. You're climbing at, say, 85 rpm. You're at 80% max, a hard but attainable pace. (I'm using my own numbers as an example).

You crest. You start to accelerate. Your cadence goes to 120 rpm. Your heart rate will sky rocket at the same time. You hit 90% max or higher and explode. The group rides away from you.

To prevent this you need to balance cadence, heart rate, and speed.

Hills typically require lower cadence. Downhills typically require bursts of pretty high cadence.

To reduce the burst cadence bits, use your gearing. As you crest, keep an eye out on your cadence. Try to keep it within a 4-5 rpm window. That's very narrow but that's the point. If you're climbing at 85 rpm, shift up as soon as you see 89 rpm. Repeat as necessary. You'll shift maybe 3-4-5 times as you crest.

The drawback is that your legs will feel kind of loaded, i.e. not as snappy as normal. You'll be pushing a bigger gear than normal on the following flat/descent. If someone launches a sharp attack, you'll be at a disadvantage.

However your heart rate will stay about even, maybe going up or down a few bpm.

As you recover you can shift into lower gears (one at a time) and increase your cadence 4-5 rpm at a time. As your cadence climbs (and your heart rate stays the same) you'll increase your legs' responsiveness to attacks. For 10-20-30 seconds you'll be a bit vulnerable, but after that you should be fine.

The only time this really doesn't work is if there's an extended false flat after the climb. This means there's no easing of the grade, which in turn means you don't have an opportunity to unload the pedals a bit and increase cadence. You end up bogging down in big gears, with less and less snap available. In false flat situations you need to either maintain a bit higher cadence or ease a bit and rely on jumping on the back as the group passes you.

This trick has gotten me over a lot of climbs with the group and able to respond to moves over the top. If you've ever seen me climb, you'll realize how significant that is for me (I'm a total non-climber).

Hope this helps,
cdr