I haven't tested it, but I went bicycling to school (7 km) when it was raining cats AND dogs (not very pleasant) one day. When I got to school it wasn't wet at all inside the backpack. So if your considering it, just buy it. I still have it, I use it everyday back and forth from school and it works wonders!
By Mickey Jo on 04 January 2014
It should fit fine into the messenger bag, my 17" dell fits in perfectl. Case is slightly elasticated also so anything slightly bigger or smaller should be fine. Can't say about the back pack I'm afraid but I'd assume it'd be the same, messenger bag is great quality.
By adrian on 22 May 2015
you can carry other things like a small (not very thick) lunch box with you. I always have some thick box with me as Iam a lecturer. I think you can accommodate enough for a day ;). Also you can always return it if it was not what you were looking for. I am happy!
By parisa on 09 October 2015
I have the Lenovo y50-70, 15.6". It fits in laptop slot easily with plenty of room on either side, so you would be able to fit your Lenovo model 17.3" in perfectly mate :)
By Hitesh Shukl on 09 June 2015