How much should I be there, and how does it help? 187 is the highest cycling heart rate I've ever recorded, 191 running.

I find myself latching onto group rides that are one step too fast for me usually. This gives me heart rate data like this.
Two average group rides for me.
http://connect.garmin.com/activity/106892501
http://connect.garmin.com/activity/102437332

Now I don't mind getting my ass kicked, then getting dropped. But am I in any way hurting myself or my progress on these rides? I feel tired after them, but neither sore, nor nauseous.

Most of my solo rides are spent in zone 3 - 4 with short bursts into 5 (usually climbing, I'm a big dude, 205)

Solo ride.
http://connect.garmin.com/activity/106708139

Thanks!