ORTLIEB Vario bag, £100, www.ortlieb.com

Ortlieb panniers are 100 percent waterproof. So a pannier-cum-rucksack with this admirable attribute is of great interest. 
In two words — it works. The Orlieb Vario takes A4 files and a laptop (protective case optional) and has a neat interior zip pocket for valuables. On the outside are two open neoprene pockets to take bottles, gloves etc, plus a detachable holder for a helmet and a useful handle. The clever bit comes with the rucksack attachment which packs away into another neoprene outer pocket or attaches in seconds to the back of the pannier. 

The rucksack is comfortable and not sweaty on the back. Well designed products like the Vario obviously come at a price, but its flexibility and functionality are hard to beat. Capacity 20-litres, three colours.