I realise this might be nitpicking, but what's best in terms of cycling ease (not convenience)? I ride to work with one side mounted pannier on a rack. I sometimes ride without the pannier and am surprised that there is a noticeable difference. Other than the additional weight, I'm thinking that the pannier is not very aerodynamic and creates a lot of drag. I also suppose that you are adding weight to the area of your bike that already has the greatest load; the rear mech; cassette and yourself. I'm thinking about going back to a rucksack. I think that the rucksack nestled behind my back will be more streamlined, the weight will be a "mobile" weight moving with my body and not a "dead" weight, and that I will be able to put the extra weight into my peddle stroke. Is this a load of bollocks?