(Custom Road Bike - Folding) Using the Brompton Frame geometry

[phillipsf]

Hey guys,

Wanted to show my folding road/gravel/commuter project here and see if anyone in the Bay Area/Cali area has seen it out in the wild!

I'm a pilot and travel in a small single engine plane, with a tiny baggage compartment. The space is small enough to fit a Brompton sized folding bike but I wanted a capable road bike that could do century rides with my friends and group rides at higher speeds (25 mph+) too. Also something that could handle Mt Tam and the Marin backcountry.

Here is what I came up with below, let me know what you think and any ideas I could make it even better!

I machined everything with my shop in USA and 2x factories in China for the frame parts and wheel set. Its pretty much the old C-line Brompton shape but redone with 20" wheels, 135m drop outs in the back for a proper cassette and everything in grade5 Titanium for no flex.

Specs
- 17.5 pounds Titanium and Carbon Fiber
- Quick Release Speed play pedals to save space for storage and convert to gravel mode (spd) or commuter (flat pedals)
- 58T and 9-36 Cassette gets 118 gear inches per rotation (standard 700c is around 125 inches)
- Sram Force Group set
- Folding drop bars into the tri-spoke allows it to be overhead capable in the commercial plane as carry-on. Also moma cubby checkable
- DLC diamond coated hardware to resist from scratches and smoother bearing rolling surface for pedal axles
- Gravel wheel set tested at Grinduro!
- Aerobars with wireless blips and 3d printed holders

Is there anything else you guys would add or think of for this? Trying to make the most capable folding bike possible

Phillip

[phillipsf]

[Pastashop]

This is the best thing I’ve seen on the bike forums in a long time! Awesome!!

[phillipsf]

Thanks pasta 🍝!

[weisan]

Very very cool!

phillip pal, I like the way you think. At one point, I got three coupled bikes, and four foldable bikes, all because I like to fly with my bikes.

When I saw your bike, the first thing that came to mind is the Bike Friday that Rob English built for himself a while back:

https://bikefriday.com/bike-models/r...e-great-white/

[phillipsf]

Thanks weisan. I love bike Friday, but the slightly bigger wheels wouldn’t allow me to fold it up and put it in the overhead compartment of the airplane! I need to do the trifold with 20 inch wheels and it just barely fits.

[NHAero]

Terrific! Thanks for sharing this.

[philhan89]

love the backstory behind this. the hands on approach with the custom machining and extensive field testing by you is SO badass. it all makes sense now! i know you been putting in the extra effort on the faster PAS rides aboard this rig. good on you man, those are hard rides. i wish you many safe happy miles! (in the air and on land)

[phillipsf]

Oh man, so if you know those PAS rides out to MT Vision and Lighthouse and back to SF (120+ miles at super fast pace) then you know...

Smaller wheels definitely not in the front of the pack, but the rider is getting little faster now! haha. Real world bike testing meant so many miles to test this out properly with competitive riders... and some hard days. But I went from 150 > 300 ftp, and clocked some 1100W sprints on that little thing!

[feynman]

That's very cool and creative. I loved some of the photo settings too.

[basilic]

This is fantastic, kudos! very creative and practical. I find the basic bromptons just too heavy to be enjoyable. What is the final weight?
What changes did you make to the frame/fork to fit 406 wheels?
What is that thing affixed to the headtube?

[phillipsf]

Final weight is only 17.5 lb! Maybe .5 less actually with some changes, but in the most practical state we're at 17.5.

The fork and triangle are big departures from the traditional Brompton setup.
It has 135mm dropouts to accept a proper XDR hub and cassette, and disc brakes. Means you can put it on a trainer too, which is a new feature for that kind of folding bike.

[hokoman]

This is pretty awesome. Can you share how much you've spent on this project? I have the Titanium Brompton, the thing that annoys me the most is that that it creaks all over....

[Mark Davison]

Bike Friday does have the Pakit with 16” wheels which folds up into a backpack. Not a full performance rig like this impressive setup. I think the Pakit is more of an urban utility bike.

See
https://bikefriday.com/product/bike-...-folding-bike/

[mass_biker]

Love this post and photos…I am the proud owner of an older BF Pocket Rocket and more recently a BF PakIt. I’ve taken that Pocket Rocket all over the place, and have been enjoying the PakIt in/around the neighborhood. I have always wondered “what if” in terms of modding these to be even more “road worthy” - and your post is inspiring!
Thank you.