it has nothing to do with what the sponsor is tellin them to ride, given that any model is in their quiver
I disagree, Cervelo would have a huge say in the bikes they want them to use. Yes, all models are "avaliable" to them, but cervelo would want to take full advantage of the advertising and "request" that the riders ride R series frames.
....yes, it is well known that riders on most pro teams are told what to ride (nothing new), often based on whatever new gadget their sponsor is trying to market. However, I have read in more then one interview that things are a bit different with Garmin. Perhaps what I have read is just more marketing drivel, but given the consistent patterns of which rider chooses which bike based on type of stage, is evidence that there are some degrees of freedom on the Garmin team (e.g. the S3 is Cervelo's newest frame which presumably is at the top of marketing priorities, but you won't find Telansky riding any of the Tour's mountain stages on the new S3 or an S5).
Here is a good example of some of the stories out there:http://www.cervelo.com/en/engineering/a ... chell.html
"We often hear those exact questions. It is important to point out that Cervélo is unique in that we don’t tell our pro riders which bike they have to ride. We let them choose. Whether it is a David Millar choosing the S5, a Dan Martin on the R5, or a Jack Bauer opting for different bikes on different days, there are only great options in the Garmin-Sharp truck"
Now, back to my response to the OP (which appears to have been misunderstood)....I was mealy suggesting that the R3 is less expensive, lighter and more comfortable then the S3. These are facts that even Cervelo engineers don't dispute, not to mention they promote in their marketing materials ( e.g. note how they describe the newly designed pencil thin seatstays on the S3 as near equivalent to the stays on the R-series frames...aiming to reach the comfort level of an R-series frame in a large aero tube bike). There is no question that all are great bikes, but given the OP's budget and the riding that he intends to engage, I was suggesting that the R3 might be the best bet. EM3