Framebuilders - Thinking of having a minibike made

Hello there - Nice to see there's a framebuilding forum now! This site keeps growing!

I've been perusing with interest and have some ideas to run by people if anyone has a moment to look at what I'm thinking about. I currently ride a 70's vintage folding Raleigh 20 to and from work daily, about an 8 mile round trip. I love the folder but actually hardly ever need to fold it having space at work and home to store it without collapsing.

I do however love the 20" 406 wheels and nimble steering / handling this affords (as well as the cute looks) and have an idea (well actually some pretty worked out plans) to make a small-wheeled city bike that fits in a space somewhere between the three points of road bike/ bmx bike/ commuter hybrid.

Bikes that fit this description seem quite popular in Japan but none are brands that seem to be marketed in Europe or the US. Seeing a fabulous custom minibike on the Fixed Gear Gallery recently, and m that Dahon have a non-folding bike [called the Hammerhead] out for 2006 has spurred my ideas, though I don't massively care for the design that Dahon have chosen as it looks top-heavy and cranky with it's curved tubes. I wanted my frame to be reasonably low in the stepover (less steel = less weight) and have a more elegant geometry than the bikes I have seen.

I want it to be simple and light. I've recently converted to fixed-gear riding so this thing would not need any brazons or gear hangers - just track ends spaced at 120mm. I'm hoping this that would be something that would keep the cost down a little too because of the lack of fiddly detailling. So it really would just be a light chromoly frame (Alu seems too rigid on a small bike), with 26" sized front disc forks (easier to source) and a set of light bars/stem/saddle and that's about it. I attach my designs made using BikeCad and embellished into a more pretty Adobe Illustrator version — My 'artists' impression (though I doubt I'll run to the £300 back wheel hehe.

Does anyone here see any obvious pitfalls in my first foray into design? I've spent some time on it and to me looks pretty final to me at least, but I've never done this before and have probably missed a million obvious things. It was drawn to scale over a 26" hybrid at the start so things like BB height, toptube length, bar height and seat height should be pretty good for me - a 5'5" 32 year old from London UK.

Also - Are there any issues to getting a 'wishbone' shaped rear seat stay a la Cannondale Badboy bikes? I really like the style of them and would like to hear if people think a custom builder would be sniffy about fabricating something like that?

Any thoughts/tips/links/info/anecdotes on getting it right appreciated really!
:)

http://www.littlepixel.info/twenty/bmx5.gif
http://www.littlepixel.info/twenty/nanovelo_bmx5.jpg

Download my BikeCAD file (http://www.littlepixel.info/twenty/bmx5.bcad)

<bump> So no-one has anything to say at all?
Hmph. Must say I'm a wee bit dissappointed!
The folding forum is a lot more friendly and sociable...

It just doesn't move that fast yet. I do like the idea, I just don't anything worthwhile to add to it.

1) I don't get why the fork is so long - why not make it shorter and the head tube longer (taller)?

2) Using track dropouts saves you nothing.

3) Braze-ons and details don't cost a lot either.

If you want to make 100 of these, I can do it for you and you can market them.

Email me at info@kogswell.com if you want to chat about it.

Now on to the interesting stuff... the illustration. How did you do the crank and chain?

That chain is a knockout.

I've done chains:
http://kogswell.com/images/chain.gif
and I know they aren't easy.

Want to do some work for me?

1) I don't get why the fork is so long - why not make it shorter and the head tube longer (taller)?
Two reasons really;
i) Seems to me that it's harder to find propriatory forks with long steerers. Having a short steerer and forks for a 26" bike solves that
ii) Lower forks would have changed the geometry making the whole thing look too elongated - like a stretched bmx. I know it's not all about aesthetics but raising the head tube means less mess up top on the stem/steerer and gives a far more pleasing result - to my eye at least.


2) Using track dropouts saves you nothing.
I know this! I specced them because I'd want to run it as a fixie is all.


3) Braze-ons and details don't cost a lot either.
Really? I find that surprising. I would have thought it would be a fiddly job and though not as important as the major joints still a real cost. Either way - I'd still not have them for a nice slinky uncluttered frame.


If you want to make 100 of these, I can do it for you and you can market them.
That's an interesting prospect! Tell me more - do you think there'd be a market for them? (Not so convinced my own folly would be popular)


info@kogswell.com[/email] if you want to chat about it.
Will do.




Illustrator CS2 on a PowerBook G4 - using the brush tool you can draw just one link that tiles and then use that pattern as an art brush to give any shape you like a 'chain' outline. The crank is just drawn with a bit of GCSE Tech drawing geometry knowhow... Glad you like the result. Your animated 3d one is pretty bling too!

[QUOTE=KogswellWant to do some work for me?
What sort of thing? Web? Blueprints? Would be interested to find out more yes!

Time to reurect the dead...
I think this is a great idea. I'm surprised that there hasn't been any more intrest in this. For the right price I would be all over this bike. I love odd little things, that are still practical and useable on a daily basis. I hope that more people see this and get some interest in a project like this.

I like this, I was planing on something similar on the folding forum like a Bike friday touring bike, but not foldable. I have some parts. In the end I am going more 26" wheel tourer, but I will probably get to this at some point. I probably wouldn't make the downtube all that fat, it can't need it from what I see of the loads on this thing, it almost seems as big as the tube on a monotube frame. Still, lots of room for the logo. I wonder how the project is coming along.

I had pm'd littlepixel about this, and he let me know that it is on the shelf for right now. But I hope to see something come of this anyway.

I have been playing with building a 20" wheeled travel bike. It won't fold but the frame seperates just forward of the seat tube. and should fit into a 26"x26" x8" case. I don't have much to show yet. I'll post something this fall when I get back into framebuilding mode

I probably wouldn't make the downtube all that fat, it can't need it from what I see of the loads on this thing, it almost seems as big as the tube on a monotube frame. Still, lots of room for the logo. I wonder how the project is coming along.

The idea is that it's an oval 'aero' tube. So not as big as it looks from the top. I kinda like the way those tubes look and yes - lots of extra room for the logo ;)

I picked up a pair of (lightly) used HED wheels recently from a really nice recumbent rider from Seattle. So they are sitting in the cellar waiting for this frame.

A question for builders - I saw a bike recently that had this specially built right hand seat/chainstay configuration so that it dipped between the chain and the wheel so that the wheel and chain could be taken off without having to split a link. I think this would be a brilliant feature on a bike like this - off with the wheels and the chain and it can go pretty much anywhere with so much less of a chance of getting oil/muck/grease all over the place. Does anyone have any thoughts on how to do this?

Interesting looking bike. Reminds me of the small-wheeled folder bikes out there. Just wondering, are you going to make this bike be available with couplers so that it can be a traveling bike? Or with those hinge thingies, so that it can be a folder? Not to knock the design as I do think it's pretty nifty looking, but comparing this bike to a folder, why would I want to buy it, when I can get a folder? Keep going on the design thoughts though because I think you might be on to something good.

@ bellweatherman.

Thanks for your words It's not entirely coincidence it's like a folder - the wheels are the same size as would be the reach between the bars and seat . I'm usually to be found in the folding boards and run a vintage(ish) folding Raleigh Twenty as my daily commuter.

The initial idea sprang out of the idea that where I worked and at home I didn't actually need to fold the bike that often - so I got to thinking about the idea of a rigid bike with those cute 20" 406 wheels so that it could fit in smaller spaces that a 700c wheeled bike if push came to shove, but would have the rigidity and lightness of those more road orientated bikes. Yes S&S couplers entered into my head and could be the sort of thing that one could do (but I've recently discovered this has been done already (http://www.bicyclespecialtiesonline.com/road_bikes1.htm). S&S couplings would be hard to do with the aero bottom tube too. So this design is a sort of halfway point between a folder and a normal bike with some of the compactness of the folder, but less weight and more rigidity. Dahon have actually just started marketing a bike made to a similar brief called the Hammerhead. Homebuilding a real folder would also present many problems I think when it comes to the hinge. I don't think they're things you can get from the average lug supplier and would have to be well fabricated and welded to measure up to the mass produced competition.

So to summarise - I think the person who'd get this bike would live in a city but might not want a folding bike because perhaps they look too strange or because they don't really need something that folds, but they want a compact bike that fits in the hallway or cellar easily, can be put on a train or in a cab sometimes.

They'd want a rigid, fast, light and unfussy bike that is nippy (small wheels are stronger and accelerate faster than bigger wheels) that can wiggle through the traffic more easily (this thing is a good 12" or more shorter from nose to tail than a big-wheeled bike.

Yes it has it's flaws and to most a folder would be a better prospect - but it's a concept that appeals to me; maybe because I'm quite diminutive in height; maybe because I like to be different from the pack, maybe just because it looks cool or maybe because I never had a proper BMX as a kid ;)