This where Brompton’s
shopping cart mode really shines - 15sec conversion; no need to lock-up outside; frame mounted so no impact to handling/steering. For larger/heavier loads, add a
Burley Travoy with good backpack - 30sec conversions; fully hand-carry/hike-able for stairs, subways, etc. and both can still be wheeled-while-folded (one in each hand).