Check picture captions for more details but I essentially scavenged a steel mountain bike frame and brazed it (using a mapp torch 😂) onto the cut off section of a Brompton triangle. And I modified a 20" mini velo fork.
Some stats:
– Entire build cost £450 including frame and all parts, other than the fancy G3ared crank which they sent me for free. I bought a complete Brompton and sold off all the parts I didn't need so net Brompton frame cost was actually negative.
– 20" wheels up to 2.25" wide tyres
– 27 speeds. 11-46T 9 speed cassette and G3ared 3 speed crank that works like a sturmey archer internal gear hub. 750% gear range from 15.2" to 113.9"
– Will weigh less than 15kg with a rack
– 113cm wheel base
– 36cm bottom bracket height
I am building it as part of Bespoked's Apocalypse Build Off in the UK, you can read about it here. I love working within arbitrary constraints and this just tickles that part of my brain haha
If you want to see how it was done, I made a video here! https://www.youtube.com/watch?v=hU5H_IaYm_k
by edtse88
7 Comments
Saw the title and first picture thought “uhuh built’
Then scrolled and… Yeah. Fair one. Lovely build!
That’s rad as hell. I love my Bromptons (349 ISO), and really like their 20” offering. You just took that to a new level OP.
And I thought brazing some v brake mounts was badass…
You absolute madman you. What a beauty. Kudos. Loved the video.
the wheelset looks absolutely horrible though lol but I’m sure you’ll manage
Wicked! I love this. Was very soroses to see the later picture of you actually ****building**** in because it looked so professional. Great design.
Amazing! I love the efforts people have gone to to make larger wheeled Brompton – they are usually much cooler than the factory job
Impressive build.