I've had my Brompton for over 4 years, taken it to Europe etc. ... but I really didn't climb anything steeper than the 14% grade to my house until I took a job in Studio City and did an AirBnB (for the week) in the hills off Coldwater Canyon.

Here's my normal daily ride:



And there's an alternate route to the same destination:



The Bike is a H6L (low gear of 29.1") and I am in the Clydesdale Class of riders.


(Guess the City)

I'm a spinner and found even the reduced gearing not low enough on some spots.
Swapped the 44T for a 39T; works better for me. towards the end of this clip; it's a
bit hard to tell in the video - but that lady is not a pedestrian. She's pushing her bike
up that steep hill(what the majority of riders do) ; while my Brompton zips along:
In this clips; my Brompton is passing a few carbon roadbikes uphill:

Yes, the -12% gearing. I live at the top of this in Carlsbad, CA (well, now only on weekends) so I knew I needed it.

I've never had problems with my Curve (305 wheel) and nexus 3 (53t cranckset x 13t cog) in Lisbon hills

I'm not going to outclimb riders who weigh 70lbs less than me :-) but fortunately, I have huge legs and can max out the leg press machine.

One consequence, I had to re-tension and true the rear wheel because the torque on the daily 28% climb had un-tensioned the "non-pulling" spokes and some of them had come loose. No big deal.

The Strava Track for the 35% ride: https://www.strava.com/activities/1556955026

Hint:

2 speed geared cranks I got the reduction gear version... as if a 50t/20t..
overdrive version, a 34t acts like a 54t

I have a Front derailleur mount ,Bought but not used, hand made steel , black gloss powder coat..

Test to see if I can post now.