I'd only head out with a 35 or 40 deg. bag. In fact, hitch-hiking from Boulder to Sun Valley Idaho in the summer of 1999, I had a 15 or 20 degree bag, and was fine.

The bag you've chosen isn't even advertised as a camping bag. I'd only use something like that in the tropics or in lowland mid-summer camping. That Lamina model seems more appropriate to touring. You don't really need uber compressibility when bike touring. That same 15/20 deg bag I mentioned above went along with me on a Belfast-Galway-Dublin bike tour and was fine. Even in July, the wind off the Atlantic on the Aran Islands was enough to make it useful.