Thanks! Easy to lose an evening doing that. It's like I was 10 again beavering away on my Rötring drawing board.



I will do. I get the impression it won't be like tomorrow but if I hear anything I'll let you know.



I'd hope that you are right. I've had a little look around and might send my design to a few with a view to getting a few quotes. If I do bite the bullet and get one made, equipping it might be over a bit of time so maybe the cost wouldn't seem so bad overall. I doubt I'd be able to run to the cost of those carbon HED wheels though haha...



Hrm. I'd rather do something closer to home for the reasons of not wasting the worlds resources shipping a bike back (kinda the same problem with one of Tony's frames) and also for reasons of not exploiting far eastern workers. The maths of it never seems really fair.



The big triangles are so that the bike has the same wheelbase at the points where the tyres hit the road. It was kinda traced over an image of a Trek 6060 - a sort of slick-wheeled mtb city bike I had stolen, so that the main points of the geometry mimic those of the bigger bike (where possible) - i.e. reach, handlebar height, bottom bracket height and steering rake. In fact the wheelbase ends up every-so-slightly longer than the bigger bike because the front wheel needed to jut out slightly to keep the same rake with the lower 406 axles. Overall: yes - it could have been lower - I have about four variations based on different heights - but to be honest it came down to the look of the thing. This size just looked right. It has good proportions. You lower the top tube and suddenly the seatstay angles look too shallow and the front too congested. There's lots of ways to crack an egg - this is just the one I thought most successful.



I'm not sure the 'centre of gravity' thing applies too much here. If you look at it without the top tube - it's not that different to a Dahon or R20 (though it would need more bracing obviously!). I can't imagine the weight of the top tube would make a whole heap of difference - especially in comparison to the weight of the rider. As I see it the 'centre of gravity' thing is more dependent on the height of the wheels. Which is the same as most folders. I may be totally wrong of course. I've just started reading 'Bicycling Science' and may find my bike would be a turkey in the flesh haha.



This is true. I have to say I find my Twenty harder to mount than it looks. Only the new ultra-low Dahon (Cappucino is it?) solves this so I can't say I'm really that bothered. I like the 'bigger bike' feel it has at this height.



I'd have to do some more accurate measurements but the idea was that if it was disc braked then the fork could be from a bigger bike like on those Kuwahara Gaaps and Airnimal Rhinos. It would especially cool with a Cannondale Lefty monostay fork, or any one of a number of forks that take a disc. The headtube would be 1 1/8" Aheadset so I think it'd be reasonably easy to find a fitting fork with a long enough steerer tube.



This is true. I love the way 406 wheels seem impervious to going out of true. But on the frame - it wasn't really born out of a notion that it must be stronger - more - that it would be a fun and compact bike that could still fit in a smallish spot with the wheels quick-released off. The look of conventionality is something that might make more conservative riders look again too. I think this is maybe where the Dahon Hammerhead might fall down - it looks a little too odd with those curved tubes and high-rise road style for their first foray into mini-bikes.



Haha well if I can get one done I'll let you know the cost. How tall are you?



I know nothing of this Tikit of which you speak! Maybe other people would be interested to get in contact with them but I think they're probably very happy with what they are doing already. I'm not sure they'd be so down with building something like this. I could be totally wrong though.



I suppose 70's style dropouts would offer the most flexibility if I ever wanted to change the drivetrain - it's a good point. I was reading all about ENO eccentric hubs yesterday - if I was foreseeing it with a lifetime just as a fixie then I could just have one of those hubs and vertical non-track dropouts but you're right - it's probably good to fit in some future proofing. I would however - leave all other cable-guide brazeons out for now to keep it's clean lines. Another thought occured that it might be good to extend the clearance of the wishbone stays so a 451 or even a 24" wheel could be snuck in at the back...



I don't think I was really thinking in terms of bettering the Twenty - more just a new project and something interesting not oft done before. I like the idea of minibikes - I hardly ever fold my bike to honest as it lives in the yard at home and in a rack at work. So I think I'm just looking to combine my love of being a little less obvious and my love of these cute small wheels with a bike that's admittedly less practical in some ways but also more elegant and simple. I was a serious Lego kid as a child and get a big buzz out of this sort of creativity. My ambition then was to design cars so bikes may be my true vocation haha... It might be another cool project to do a 2006 Twenty based on more modern, lighter materials but I'd say this area is almost covered - especially by bikes like the KHS Westwood which is so similar a geometry - so in a way off less interest as it's kinda like reinventing the wheel.



And me too!
Huw