Red Lining

[Nightsbane]

If you don't have a tach, how do you know if you are?

I am currently commuting this fall to class about 25 min away. I am not wanting to damage the bike. I know height, weight, hills, wind affect speed, but how do I know if I am running it too hard? Just trying to be careful. There is one stretch for five miles where it's low traffic and still only two lane, but 65mph. I'm 6ft, 200 pounds.