I have a fair collection of Rapha items but that Rapha bag is really small. You could maybe fit a small laptop in there with a t-shirt and a U-lock. Without the laptop, substitute a jacket and sandwich. Just not worth it; get a Camelback or something similar for $50-$75.

FWIW, the only Rapha stuff worth a damn to me are the jerseys, bibs, and the original softshell.