On our first extended winter trip (to southeast AZ and Southern CA) we carried our two mountain bikes on the back of the TM. The
bike rack was an Outback model that could carry up to 4 bikes and had a quick release pin to lower the
rack out of the way. We had to lower the bikes each time the TM was opened otherwise the rear shell would not clear the top of the bikes. There were a few times we bottomed out with
bike rack during our travels. We did notice a difference in the pulling characteristics when the bikes were on the back of the TM. There was more of a porpoise effect between the TV and the TM. Also noticeable was the extra slop in the
rack which was meticulously taken care by a series ratcheting straps and bungee cords. We did get better at removing the straps and bungees each time the TM was opened and reversing the process the next day. It did get old fast . . . especially when raining.
The next year we decided to add a front receiver to our TV and get a different
bike rack (
http://www.etrailer.com/Merchant2/me...gory_Code=BR2B). The new set up no longer interferes with opening or closing the TM. While this particular
rack does not drop down, it takes about 1 minute to remove or install each
bike. We do remove the
bike seats when traveling as they will hamper visibility. We feel more comfortable being able to see the bikes and no longer worry about whether or not they have come loose of fallen off (going down the highway). Over time the extra weight (of the bikes and
rack on the back of the TM) could cause problems with the bumper welds. I understand the newer TM's don't have the 2" receiver bolted to the back bumper. Instead the receiver is welded to the frame of the TM . . . a much better arrangement.
http://picasaweb.google.com/commodor47/FrontBikeRack#
It looks like you have 5 choices when it comes to carrying bikes: inside the TM; back bumper of the TM; between the TV and the TM; on the roof of the TV; in front of the TV. It sure is nice to have the bikes available when camping though!
Good luck on your choice and happy biking!