@ascentale @xtaran @bikenite Most of my bikes have boring derailleur drivetrains, but I have a Brompton folding bike with a 78-speed gear hub and a double chaining with no derailleur (the chain tensioner that's needed for the fold can take up the difference in chain length).

You have to pick the chain up and hook it over the big chainring by hand, but with a bit of skill you can kick it down to the smaller one with your toe while pedalling. In practice, it gives me an extra ratio at the top or bottom of the gear range, so I tend to pick one according to the hilliness of the place I'm riding in, and leave it there for the duration of the ride.

@kim @ascentale @bikenite #BikeNite A3 follow-up: A Brompton with 7-speed hub gear sounds non-standard. I so far only know of 1,2 (sprockets), 3 (hub, BSR/BWR), 4 (sprockets), 5 (old Sturmey Archer hub), 6 (2×3), 8 (Alfine in the G-Line) and 12 (4×3) gears ex-works, but not 7. Front derailleurs seem non-trivial with the Brompton due to the bottom bracket not sitting at the bottom end of the seatpost, but in front of it.