New to the forum and appreciate all the info you all have shared! I know this is an old thread, but I thought I'd add to it anyway in case someone is still looking out there as I was. My husband and I just purchased our first carbon road bikes (Giant Avila and men's Defy), and had the same question about what kind of bike rack for the back of the car. Did a lot of research online, then asked at the local bike shop (LBS).

We wanted 4 things: 1) something that would not damage a carbon frame, 2) a hitch mount that could be for both a 2" or 1.25" inch, 2) something light that I could install/take off myself, w/o my husband's help, for those rides when he's not around, and 4) a reasonable price.

We are really happy with the SARIS Thelma (2 bike rack) at the very reasonable price of $272. http://www.saris.com/en/bike-racks/v...&category_id=8

Nothing touches or wraps around the frame, only the 2 wheels of the bike are tied down with very study plastic ties on a hard plastic cradle for the tires. The whole thing weighs about 26 pounds, which is amazing given how heavy the comparable Yakima and Thule platform hitch racks cost. Once you figure out how the whole thing works, you can lift the bike on the platform, scoop the cradle for the front wheel into its forward position and it locks into place; unlock it to take it off, the front wheel support flattens down, and just a short lift down to the ground. When not in use it can fold up against the car. The car fits in the garage even with the bikes on the platform.

The best part was all the help from the LBS (Shark West in Chesterfield, MO): it had two employees who could recommend it (and I got to see it in the parking lot), it highly recommended the company (made in USA and warranty), they recommended a Thule threaded locking bolt so no one could walk off with the bike rack that also stabilizes it, and BEST of all: the LBS put the rack all together for me and even attached it the car and showed me how to work it! Even though the LBS didn't have it on the floor, it was able to order it from Saris online.

The LBS also mentioned that a customer recently bought the Thule Helium, which holds the top tube of the bike. She had a carbon bike and was warned not to tighten the straps; however, turns out she ended up tightening the straps a little too much, and it cracked the top carbon tube. LBS also mentioned he has the Thule T2, and it's so heavy his wife can't put in on or take it off by herself, and he admitted it's even a little too heavy for him.

One last minor issue, if the bikes or rack block your license plate in some states, like MO or TX (and there are others), you can be ticketed 70-100+. Saris, Uhaul, the LBS, and RMV (no duplicate license plate was possible) all had no solutions, but my husband came up with one: take a color pic of the license plate, laminate it, cut 2 slots and insert velcro strips to hang on the outside bike (or the rack when folded up).