Haven't posted in this thread for a while since I just end up giving a weather report, but in that spirit...
Lately my commutes home have been about 78-80 F. This is without doubt the perfect cycling temperature. I love it, a little cooler and its gets too nippy and it takes too long to warm up, a little warmer and you need to drink more. I love it! Correspondingly my speeds have increased to where they were in April before it got really hot.
Al