Prototype 20" Brompton

[Origamist]

What ever it is, it looks way better then a normal Brompton. I'll be in the market for a new folder later this year. Not going to go down the Brompton 16 again, so may have a look at one of these if they are released by then.

Hi Ian, hope you're well.

I'd not hold your breath on this model being available this year. A couple of years, maybe? If I didn't have a Kinetics Brompton, I'd be all over this!

Not sure what you're after in terms of a new folder, but you can pick up a 8 speed Tern BYB at a discounted price at the moment. Smaller fold than most 20" folders, but a bit fiddly. Good tyre clearance and adjustable cockpit.

 

[ianrauk]

Hi Ian, hope you're well.

I'd not hold your breath on this model being available this year. A couple of years, maybe? If I didn't have a Kinetics Brompton, I'd be all over this!

Not sure what you're after in terms of a new folder, but you can pick up a 8 speed Tern BYB at a discounted price at the moment. Smaller fold than most 20" folders, but a bit fiddly. Good tyre clearance and adjustable cockpit.

Hey chap, good to see you back on here.
I have actually been looking at Terns, specifically the D9.

 

[rogerzilla]

Moulton have been quietly making wheels bigger since the company was relaunched in the 80s. They haven't used 16" wheels since the original firm was sold to Raleigh and the line died out.

The 17" size has very limited tyre choice (although they still use it) but most Moultons are now 20"; the "Pashley Moultons" and the New Series. Bigger wheels just roll better, if you can package them. Brompton must be coming to the same conclusion.

 

[berlinonaut]

I'd not hold your breath on this model being available this year. A couple of years, maybe?

I'd agree with that. WBA talked about a "revolutionary new product" in conjunction with announcing the build of the new factory in Kent. Possibly the 20" is this new product and possibly it will enter the market only after the move to the new factory.

 

[Origamist]

Moulton have been quietly making wheels bigger since the company was relaunched in the 80s. They haven't used 16" wheels since the original firm was sold to Raleigh and the line died out.

The 17" size has very limited tyre choice (although they still use it) but most Moultons are now 20"; the "Pashley Moultons" and the New Series. Bigger wheels just roll better, if you can package them. Brompton must be coming to the same conclusion.

I often think a 17/369 Brompton with decent tyre clearance would have been the sweet spot in terms of fold and handling, but what do I know.

 

[berlinonaut]

I often think a 17/369 Brompton with decent tyre clearance would have been the sweet spot in terms of fold and handling, but what do I know.

Given that there are only Kojaks available in that size (and off the beaten track the Strozapretis and the Bridgestone tire) this would have been a miserable choice, at least from today's perspective.
What one should have in mind is what the constraints and targets were when the Brompton was designed. A lot of the design decisions followed the goal to fit in the train compartments of the time when the Brompton was designed. This led i.e. to the original smallish roller wheels of the MK2. Possibly the tire size was part of that, too (and Brompton had to use what existed in opposite to today where the shear amount of Bromptons produced and around opens a market for itself, so they are less dependent from existing things but often can define things).
Today the world has changed as have the train compartments (and technical possibilities as well as the financial situation of the company) and thus there's more freedom today for the design than it was back then.

 

[Origamist]

Given that there are only Kojaks available in that size (and off the beaten track the Strozapretis and the Bridgestone tire) this would have been a miserable choice, at least from today's perspective.
What one should have in mind is what the constraints and targets were when the Brompton was designed. A lot of the design decisions followed the goal to fit in the train compartments of the time when the Brompton was designed. This led i.e. to the original smallish roller wheels of the MK2. Possibly the tire size was part of that, too (and Brompton had to use what existed in opposite to today where the shear amount of Bromptons produced and around opens a market for itself, so they are less dependent from existing things but often can define things).
Today the world has changed as have the train compartments (and technical possibilities as well as the financial situation of the company) and thus there's more freedom today for the design than it was back then.

Yes, the 17" wheel has been slowly rotating towards obsolescence for decades. In the mid 2000s, I thought of upgrading my Birdy with 17" wheels, but the limitations of tyre and rim choice put me off then.

I'm not sure if 369 wheels were experimented with by Andrew Ritchie back in the day, but I imagine they were at least, considered. I'm sure you're right that engineering and compactness of fold were key considerations as was the relatively narrow size of most 369 tyres: approx 32mm. Dunlop was the main tyre manufacturer in this size, pre-2000, as I recall.

When I was getting my Kinetics stretch conversion, what I really wanted was 17" wheels and 40mm tyres....Dreams, eh?

 

[Fastpedaller]

Like all bicycles it will be a compromise - possibly a 'better' ride for some (IMHO the Brompton is fine) but undoubtedly the fold won't be as compact?
I've not done any detailed investigation, but for me a more standard (130mm?) OLN dimension would open up more possibilities (and gears), but again may prove less compact.

 

[berlinonaut]

Like all bicycles it will be a compromise - possibly a 'better' ride for some (IMHO the Brompton is fine) but undoubtedly the fold won't be as compact?
I've not done any detailed investigation, but for me a more standard (130mm?) OLN dimension would open up more possibilities (and gears), but again may prove less compact.

My ETRO 349 Cooper Brommi with disk brakes and a 135mm OLD rear frame with a Rohloff hub folds to the same size but the folded package needs a bit more depth. So in comparison with my 2 speed there are spaces in trains where the 2 speed (or any stock Brompton) fits but the Cooper doesn't. The difference is small, the effects in certain situations are not. But then again the advantages I get from the Rohloff over the 2 speed (or a BWR Brommi) are also huge, so you trade one for the other. Having the luxury of owning both and thus being able to pick according to the situation is nice.

 

[ExBrit]

Seen at the junction with Caledonian Rd, London.

I've heard talk of a 20" model for many years. Looks like we're nearly there? This version looks to be electric...

Lots of talking points...

Image courtesy of @dr_brompton

View attachment 674656

What's all that dirt on the rear fender? That didn't come from the road. It looks like the rider got very nervous at some point in the ride

 

[Origamist]

What's all that dirt on the rear fender? That didn't come from the road. It looks like the rider got very nervous at some point in the ride

Probably due to all the Brompton folding bike enthusiasts stalking him and snapping pics of his bike and backside at every junction....

 

[rualexander]

A high BB is not good in what is (normally) a town bike. Back in the 60s, Moulton ruined the series 2 by giving it rear forks which are stronger, but raise the saddle by about 3/4". That's the difference between being able to get a foot down at traffic lights, or having to dismount.

On most traditional bikes set up correctly you can't put a foot down easily at traffic lights without getting off the saddle, you might just manage a tiptoe but most people will get off the saddle and stand flat with one foot, which is even easier on a Brompton.

 

[berlinonaut]

On most traditional bikes set up correctly you can't put a foot down easily at traffic lights without getting off the saddle, you might just manage a tiptoe but most people will get off the saddle and stand flat with one foot, which is even easier on a Brompton.

True, still there is a massive difference in height that makes this exercise more uncomfortable.
Normal Brompton:

Bromptosaurus:

 

[MichaelW2]

Is the 20" Brommie an XXL version for big guys? If so the high bottom bracket could be for their XXL crank length.
Now we need a 12" tiny Brommie for the little people.

 

[berlinonaut]

Now we need a 12" tiny Brommie for the little people.

Here you go. It is called "Bromptolino" and, as the Bromptosaurus, created by Juliane Neuss.

It is intended for vertically challenged people - creating bikes suitable to their special needs is one of her areas of specialization apart from Brompton: https://junik-hpv.de/arbeitsbereiche/fahrraeder-fuer-kleinwuechsige-menschen/
The Bromptolino is btw. fully reversible - you can build it back to a normal Brompton if you like.