I'm an avid XC mountain biker, and now my orthopedist says I can no longer hike or run for fitness, and swimming doesn't appeal to me. So I'm looking into road biking for fitness. I own a high-end mountain bike, and since I'm not sure whether or not I'll like road biking, I don't want to spend big bucks just yet. Also, I have a lumbar issue, so I'm thinking an upright bike, hence the Trek FX. (I also tried a Trek Lexa SLT that I liked, but I'm not sure whether I'll ride 30 miles, 60 miles, or 100 miles, so I'd rather not get the Lexa unless I know I'll be road riding for a long time.) I have lots of mountain and canyon roads and the popular rolling coast highway to ride near my house. I do not plan on using this bike on a dirt trail, except maybe on the sand along the beach near my home. Oh, and I like climbing, and I'm a bit competitive.
Should I buy the entry level Trek FX 7.2 or the higher caliber component, lighter bike Trek 7.5? Thanks in advance for any advice.