Originally Posted by
Tourist in MSN
For rear panniers, if you get larger panniers than you really need, you have the capacity if:
- you decide to carry some extra water bottles or
- if you buy some extra bread for a picnic lunch or
- if you get the urge to buy a six pack or
- etc.
The front Ortliebs at 25L are a good size for one reason - it forces you to avoid putting too much weight on the front rack.
If you really are considering that small of a set of panniers for the rear for credit card touring, you might also consider getting one of the rack trunks that have zip out mini panniers. I think the combination is even larger volume than the front Ortliebs and they are quite light. They also work well around town as a normal rack trunk when you do not need the extra volume you get with the panniers.
With the great price that popped up on bestbuy.com for the Ortlieb rear panniers (only $10 more than for the fronts) recently, I decided to go with the bigger pannier, for all of the reasons you cited. I saw the rack trunks, but was concerned that the mini-panniers with them wouldn't be substantial enough.