AER Go Pack vs The North Face Surge II Daypack

These are going to be more suitable for ‘true’ one bagging (ie when you travel without a checked bag). If you decide to opt against a checked bag, perhaps look at a packable day bag and one of your options above, or take a look at the Peak Design Travel Bag, as this is designed with photographers in mind, is effectively a big bucket of a bag, and can expand from 35-45l (although I think when expanded to the full 45l it is slightly too big for most airlines). For a daily carry, you ideally want to be looking at something 25l or less, even under 20l.

4) Still gotta use this on a mountain bike. The back is breathable - but its a big bag. I'll update this after the first ride. There is no bladder option on this bag (unless you hack the laptop area)