Lovely piece of design Allan – well done. What does it weigh?

Rik

Call it the 'Jackson 5×2'.

Well done Alan nice looking cycle, looks like we've got another Dr David Hon in our mists, he spent 7 yrs developing a folding bicycle in his garage & took his design to leading manufacturers who wern't interested, so with his brother he started his own company,[dahon] they are now the largest folding bike manufacturers in the world, I have a dahon cadenza, it has 8 hub gear speeds [none of the exposed derailleur gears & sprockets to gather dirt & salt,] a stainless steel chain disk brakes & full size wheels, a beautifull bike.

Graham.

My wife and I took a couple of Dahon folding bikes on a world tour last year, which meant they had to fit into a standard airline check in bag size. That means 1580mm max total dimensions of the bag, and under 23 kg. So small bikes are of interest, since the trip was successful enough that we would love to do the same sort of thing again. This looks like a promising design, but I would echo the question someone asked above, what is the gearing like. It is hard to get a high enough top gear with small wheels. Not that you are going to want to go extremely fast…my Dahon has the 16 inch wheels and an 8 speed derailleur. The bottom gear is plenty low enough, the top could be a little higher but it is really hard to do that since you need a larger front sprocket. It has been done but they are hard to get, I might have to make one. The gear hub inside the back wheel is a good idea, again provided you can manage to source something suitable.

The other thing I would suggest thinking about is a carrier of some sort. My wife's Dahon came with one and it does not significantly affect the folded size. I had to buy and fit one for mine, which meant a bit of modification on the milling machine, but again it can be left on when folded and still fit the airline bag. I did fit it using quick release fasteners so that it can be taken off easily. Even if you do not plan airline travel, one of the good uses for a folding bike is trips to the shops from either a small apartment or even a caravan or campervan. (US RV) You may not need (or want!) to carry a lot of stuff but it is a handy thing to be able to do. We were able to fold down the big bag once the bike was out and strap it on the little carrier, wear the carry on, and bicycle to our bed and breakfast places.

The Dahons are around the 11 or 12 kg mark, which leaves a bit of extra available in the bag to carry clothes etc. Between that and our carry on bags, we were able to travel for two months quite comfortably. Of course there are little expedients to keep the weight of the bags down, like wearing the camera and keeping the lenses in my pockets.

Bikes are a bit frustrating, when you think that the 12 kg or so of mostly aluminium should be able to pack down into under 30 litres or so, if only there was a simple way to do that. Well, we could pack it down OK by melting it, but getting it unpacked would be more of a challenge.

John

More than a step ahead!

Given the expense and complication of the patent process, I assume you are serious about production. Your experience of the main stream bike industry is fairly typical I think. At first sight, your vastly impressive design appears to use only two standard items ie the saddle and one pedal (? brakes and bar grips).

I think that 50" would be OK for some of the purposes mentioned by John Olsen but a utility folder really needs mudguards and luggage capacity.

I like the rectangular seat tube which does away with the need for radial adjustment when unfolding.

Position on bike is both personal and use-dependant. It looks as though the rider on your machine will be sitting almost directly over the rear wheel; how does it perform on hills?

Those elegant disc wheels are no doubt your own design and manufacture. I did wonder about their lateral stiffness.

I hope you will keep us up to date with your progress in the refinement of this most interesting project and perhaps post a video of the folding process.

One of the problems with small wheels is hysteresis losses in the tyres so you need to overcome this with high pressures. Alex Moulten overcame this problem by introducing suspension. With the design above I forsee a rather uncomfortable ride with the upright seating position above the rear wheel.

Rod

Alan

Thanks for the further comments and information.

Might you provide a link to the patent documents? Your point about needing to protect your design before showing it reminds me of the experience of Andrew Ritchie when he was developing the Brompton – a long and rocky road.

Gearing and crank length go together of course. I believe that cranks as short as 100mm have been used by experimenters. Being able to put both feet to the ground without leaving the saddle is a strong point for "minimum mode" users.

I take it that you could incorporate an epicyclic hub gear in the rear wheel if necessary but this would add relatively significant weight; the present low weight is a strong feature. I endorse your comment about the difficulty of carrying a folded Brompton. A motor and battery would add even more weight although the hub gear could be dispensed with for "minimum mode".

Is the gas strut intended to provide suspension? The plain bearing main pivot on the Brompton is a weak point although it seems not have hampered its great popularity. The rear suspension on the Brompton can be tuned by using stiffer or softer media. Some years ago they altered the front frame hinge effectively increasing the wheelbase by about 30mm which I think had a beneficial effect on the ride (I have owned both types).

Studying the patent with great interest; it answers my query about the folding process, of course. I note that you were your own agent!