Thanks for the replies. Most of the reviews I've read about the QuickTrack are positive and say that it works well, but I've read few reviews that say it's not sturdy enough. The zippers in Topeak bags have got a lot of negative comments too. Also the material quality is not the best what I've read. I read reviews from amazon.com and rei.com.

How about the fastening mechanisms on all products. Is clip straps worst? How about velcro straps, will they keep the bag in place or will the bag move sideways? Ortlieb's locking mechanism would work with any rack which is a plus and additional lock can be purchased to prevent theft. Topeak's as mentioned needs their own rack and doesn't have theft preventing locks. But which locking stystem is better?

Could you measure the width, lenght and height of the main pocket for me so I know if it can fit my lunch boxes?