The last thing I have to fix on the Brompton is hand comfort. Even with the Ergon bar-ends the M bars just don't have enough hand positions to be comfortable for long rides. I also keep finding myself wishing for drops when there's a head-wind. I found these clip-on drop bars on Amazon that solve both these problems.
They are low-profile, ergonomic, clip-on drops for $24 a pair. They are not really compatible with the Ergon GP3 bar-ends so I drilled out the ends of the handlebar grips that originally came on the Brompton and slid them all the way onto a pair of S bars so that I had room to attach these drops. I could see replacing them with Ergon GP1 which would be an improvement over the original grips.
I also added a Satori 4cm riser for the handlebar which put it at a very good height for me. Here's how it looks with my new custom 3D printed Wahoo mount.
I printed my own Wahoo mount because all the Wahoo handlebar mounts I could find on Amazon project too far forward and strike the wheel when the bike is collapsed. Because these drops are compact and I turn them slightly up to get a good "brakehood" hand position, they don't take any more room than the M bars do when the bike is folded.
I rode a fifty mile ride on the new drops and I love them. I swear they are 50% more comfortable and 10% more efficient. I will never get to road bike efficiency because of the Brompton drive train and wheels but I am getting close in terms of air resistance.
Here's the new custom low-profile Wahoo handlebar mount. It attaches with a hoseclamp.
This is fun.