Different people aim at different features in their bikes. I aim at utility under my circumstances and am about finished tweaking my Brompton. The highlights, some of which were individually reported before, are as follows:

• 27 Gears, in practice 15, evenly spanning the range from 1.05 to 8.6 development meters
• Twist shifters, with operation aligned with that common on bikes
• Rear rack equipped with stronger than original, titanium stays
• Added transverse roller wheels to make it possible to roll the bike like a suitcase
• Two kickstands, center & rear, to make the bike stand with a fully loaded 15kg+ T-bag
• Lock bag holding an Abus 6500 folding lock
• Accessory bar taking phone, radio, power banks, camera etc.
• Cloth bottle bag that also serves as a container for small pieces and has a concealed pocket with a USB charger and spare cable
• T-bag turned into a backpack

You might say that I could start with a Bike Friday and have a lot of gears and twist shifters at that start, but I cannot make the BF's fold as small and convenient as Brompton's. Photos illustrate the features. I should now pause now with tweaking. The weight is 15.6kg w/o lock and 17.2kg w/lock (you are free to laugh here).

Dude, if you're happy with it that is all that matters! Fortunately, we live in a world where there are different bikes available to fit our unique needs. Your bike sounds like a beast - meaning very durable. The weight would kill me, but that's obviously not important to you, or at least not primary. Glad you got it sorted the way you want it; now just enjoy the heck out of it =).

I love your set-up....I too enjoy solving problems pertinent to personalizing my vehicles, to suit....ME!

The accesory bar you fabricated is the shizz!

What is the black disc I see at your triangle pivot? Can you provide some info?

I use 2 types of mechanical coupling between different pieces, tripod thread + velcro. Phones have velcro on their backs and so have power banks and pouches protecting from rain. The disk has opposing velcros on 2 sides and it is connected with ballhead tripod mount to the accessory bar. You can attach power bank underneath the disk or sandwich it between disk and phone. All can be moved to a car and mounted there, put on a QR mount on another bike etc. The key is to standardize couplings just like with USB for electric.

The weight of course matters. My practical solution has been, like with a suitcase weight, to make the bike very rollable. I decided against a number of aftermarket options that could save weight, but looked way too fragile. I cannot afford the bike breaking under conditions where I am completely out of my element and yes sometimes my life can depend on it.

All I was saying is it sounds like durability is more important to you than the weight, thus the modifications. Priorities. It's your bike and you know how you use it. I personally think it's great that you were able to achieve the end result you wanted and hope you enjoy it for many years to come =).

27 gears = BWR + three sprocket cassette + triple crankset ?

What front mech do you use?

Very interesting and unique Brompton. I am confused about the second kickstand. I see one in the back, holding the bike up, and something behind it. What is that?

Also on the non drive side where hinge for folding the rear wheel under, what is that?

Is your shifter for the sprockets indexed?

If you installed a mountain drive you could have 54 gears!

Correct
I use Suntour XC Pro, but I tweaked the cage a bit using a stainless steel soldering kit and pieces of stainless steel to improve shifting. I added a piece of sheet steel to the inner side of outer cage, in the middle, to improve the downward shift from the middle to small ring. I added a piece of sheet steel to the bottom of back cage, to improve the upward shift from small to middle ring. The downward shift problem is there because the seat tube is of a large diameter and the derailleur cannot go far enough in. The problem should be there for any folder with a large diameter seat tube including Dahon and Birdy. The upward shift problem is there because of a large size difference between small and middle ring in my 20-32-50 setup. I must say that one could get an OK shifting without cage modification, but with the modification the shifting is more robust - no matter what you do, it shifts fine.

I think you refer to the second kickstand, folded in the photo. I use a Kamoya center-mounted kickstand.

https://www.kamoya-ne.com/?pid=51274909

All my 3 shifters are indexed. Yes, indeed, but the mountain drive would add 1kg of weight or something close to that. At this point I am fine with the gears , but @pastorbobnlnh has 54 on his Dahon !

More pics! Great tips
I would love to see how you did the transverse roller wheels, and kamoya stand. (Cyclodonia has them, gorgeous stuff there )
I have too many rough sidewalks in my life.
Brompton needs to keep that reinforcing bar for the old M bars in production, hose clamps are just inelegant. Useful but bulky and snag things.

I'm Ok with 6 (17 ~ 77 g") BSR + MD that gram counters dismiss ..

Modified an older front bag frame to carry boxes & so forth.*. (same house of commons bench seat green)

Schmidt new XS hub, B&M Eyc Head + toplight line tail, lights ..

Carradice SQR bag on seat post..

* or Touring and an O bag ..





(Nice shoes ! matches the brake lever covers color ..)








...

Hm, so I have added a third cog with a friction shifter so it could work with an SA 3-speed indexed?

Why two kickstands?

Also, on your rear dropout, non drive side, there is some thing else there beside the kickstand. What is it?

Thanks

It is raining cats and dogs here today and during the day I am at work, but I will try something. There is a post there in the past on the transverse rollers.


Yes, any 3-speed indexed shifter should work. Some shifters are weak but not much force is needed to pull the Brompton rear derailleur.

The two kickstands are there because I sometimes heavily load the T-bag and the bike might lose balance with the T-bag on and only one kickstand active. Kamoya acts as a backup.

By the axle you have a Radical Design trailer hitch designed specifically for Brompton. They make it for use with their own trailers, but you can adapt any other trailer to work and I have used it with Bike Friday system.

OK here are 2 kickstands deployed. The Kamoya is activated in difficult situations, heavy T-bag possibly combined with inconvenient alignment with a slope.

Nice bike (for certain philosophers https://en.wikipedia.org/wiki/Utilitarianism). Thinking about it mine (H6RD) is more of a Rationalist Brompton (https://en.wikipedia.org/wiki/Rationalism).

2_i Did you add or do have an inline cable adjuster on your derailler?

I use Ritchey adjusting barrels, see the photo, for the rear cog shifter and front triple shifter. I put a heat shrink over the barrel for the rear in order to absorb the large slack that the cable has for the smallest cog position. There is another manufacturer of such barrels, maybe Jagwire.

Thanks

How did you make the accessory bar mount? It looks like you rigged up something? TIA

It is a stock alu tube, with ends shaped to fit the handlebars and small cuts made to pass hose clamps through, for holding the tube against the handlebars. The tube needs to be pushed slightly back, towards the rider, so that it does not interfere with the fork upon folding. It takes about half an hour to shape that tube, provided you do not need to redo anything. The ends of the tube may be hammered slightly to wrap them a bit around the handlebars.

Seems that about 3 years after this first post, you still have your Brompton.

Either you are very lucky or you didn't use often the bike thieves beloved Abus Bordo 6500 !?

Of course I have it. It has evolved a bit, but I still secure it, here and there, with the 6500. I did not know that the latter lock is loved so much . I usually go by the nose in precautions and these, of course, are never quite perfect. I once parked a moped in France and secured it, to make a phone call, but I did not empty the tool pouch by the seat, holding a single screwdriver. I turned around and then back towards the moped and the screwdriver managed already to depart from the pouch. On the other hand, I regularly secured the Brompton with the Abus in provincial France and went on shopping and all was good.

Commercially available:

https://www.etsy.com/listing/1141802...sr_gallery-1-1

These are for later made Bromptons.

OK, here is the 7/8"=22.2mm tube shaped into the crossbar. The tools are a saw and a round and a flat files. The small cuts for the hose clamp can be made with a dremel or with a combination of a saw and a knife. Alu is soft. The length and the slight angles for the ends depend on the intended elevation for the crossbar within the M-bars.