Interesting because I just posted this thread above:
"I have a new Rivendell which I will now become my main commuter but at times I'd like to still take my Specialized Tarmac to work. I've used the Tarmac for many years but the commute started to become more uncomfortable as I got older since I was also wearing a backpack with my change of clothes and other work related items. I purchased a Carradice tail bag for my Rivendall but was wondering if I could also connect one of the Bagman QR supports to the rails of the carbon seat stem so I can use the Carradice on that bike also. Has anyone ever used a Bagman on a carbon stem and do you see any issues with having it attached since it only connects to the aluminum seat rails?"
I live in Atlanta and don't really have any issues with a sweaty back from a backpack but I do have issues with the weight on my back, It really makes my commute less enjoyable having to deal with the weight and occasional shifting straps which is why I asked if a bagman QR would work on a road bike with CF seat post. I'd be free of the backpack if I could make the Carradice bag work. I also read that one of these bags could be strapped to the handlebars of a road bike but since I have the larger Nelson bag I'm not sure how that would work. I left the bag at work so I'm not able to give it a try at the moment but just based on the size of the Nelson it seems like a tight fit. I also would rather have the weight on the back instead of on my front steering.