I try to never go below 6.5mph on any climb, but on a long ride...like over 50+ miles I'll drop down to 5mph. I try to stay between 7.5-10mph on a serious climb. I'm kind of sick of climbing...I wouldn't mind some flats...just can't find them here. But you know the grass is always greener. I'd be bored in a flat area.
I know people that stay at 14-15 mph on the same climbs that I do 7-9mph. damn them