I'm contemplating selling my '09 Roubaix and moving to an '11 Tarmac. Why? The Tarmac is significantly lighter (a Tarmac module weighs about the same as a Roubaix frame -- not a heavy frame, but . . . ). And the Tarmac will likely handle a little more crisply on steep, technical descents.

But I still have questions that a 20-mile test ride is not likely to answer. For one . . . before I got my Roubaix, I had no problem with comfort on a racing-geometry bike. Is the Tarmac noticeably harsher than a Roubaix on chipseal and smooth roads? Second, if I use the same number of spacers under the stem, will I really notice that much of a position difference? The head tube difference is about 3/4". Will I really notice the difference? Over short distances, I don't see any issues here. The Tarmac will require a tad more vigilance to keep in a straight line. But, for 75, 80, 100 miles, (for those who have ridden both), is there really a massive difference between how the two bikes ride?