Unless you are a seasoned rider and already have 80 mile rides under your belt, I would be very surprised to see someone get on a new bike and ride 80 miles. But, each person is different and you may be fine. Does your bike shop want the bike back after 100 miles to check it out. Your cables will stretch, and things may need adjusted.
Have fun if you go!!!!!!!!!!!
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2007 Jamis Ventura Comp
2006 Jamis Explorer 2.0
2000 Specialized Hardrock (bought used)
Swim, Bike, Run and sounds like fun