This came on the Mountaineer frame only with an extension crossbar, was a full length bag, with a separate bottom compartment meant for a sleeping bag
[Update from Smart: "The motor assist controls have been moved to a lift thumb shift on all new retail versions of the bike," so buy in the UK from new and you'll gain this benefit.] It's not all just about speed though: the built-in front and rear LED lights can also be controlled from the centre controller
This larger size is also ideal if you regularly haul binoculars or a DSLR camera, will be carrying gear and food for others, or want room to stash a book, hammock, or packable blanket for a mid-hike picnic
Valuables are placed closer to your body, protecting them from theft
The Aerohead also has a forward-overhanging shape that Giro claims is fast over a spectrum of head positions