Pros: All in one
Cons: Needs some exposed seatpost.
Want a bag for a triathlon? Want a bag you can quickly take in the shop? Want a bag that doesn't need a rack? Want a bag with a HI-VIZ rain cover? This does it all!
As you can see the bag fixes by a special seatpost extender to the KlickFix bracket (both needed and included in above price) and the clamp band goes up to 32mm diameter. I have seen a 5Kg weight restriction quoted for the clamp and bracket, but don't worry I had way more than that in it. In fact I did 9 days of touring with this bag alone on the northern half of Lands End to John o Groats. It has outside pockets to get at your midge repellent and sun lotion quickly. It has secure pockets inside for valuables. If it rains you pull out the cover from another pocket & easily it is on. You can leave this bright yellow cover on all the time if you wish and obtain really good visibility for Mr. Half-a-Glimpse. It takes only a moment to get the knack of detaching and reattaching the bag to the bike, then you have no worries of someone stealing your stuff while visiting that stately home or castle. The bag is also very comfortable as a rucksack. The bag is no lightweight but you don't need the rack on your bike so the total is about the same as a rack and one pannier and then has the same 26 litres of space - enough for a week or more in hotels/hostels.