Originally Posted by
fsrgp
One thing I didn't mention is that I have a very bad back (3 fused vert. in lower spine), thats why I thought a comfort bike would be best (more upright sitting position).
Not necessarily. The forward position on a road bike supports your spine at both ends. All that upper body weight is moved off the lower spine to the arms. An upright puts all the weight on just one end. Flexibility is another issue entirely. And I still think a comfort hybrid is the place to start.
Originally Posted by
fsrgp
Would renting a few bikes over the next few weeks to try them, for more than a trip around the parking lot, be a good Idea? That would set my purchase back awhile.
That's actually a pretty good idea, provided you can rent one like you're looking to buy. As MinnMan says, that could be the hard part. But, even if the rental bikes are different, you might find that renting one for a weekend will ally all your fears, and then you can proceed with your purchase with a little first-hand knowledge of yourself.