Monday, November 3, 2008

my shot at bike design contest.

D: the bike must be
1) easy
2) comfy
3) efficient
4) fun.

D: this reminds me of the old mechanic joke. You can have 2 out of 3 of the following. Cheap, fast, good. You can have good and cheap but not fast. And so on....

1) easy. I assume this means easy to operate for the end-user. No fancy controls. No complex technical aspects
2) comfy. Ergonomics. Feels good.
3) efficient. This one is trickier. This sounds like 'light' to me, with good gearing.
4) fun. I imagine 123 would make it fun. Not dealing with technical stuff is also fun.

Well, the above bike is just a 26" wheel DIY version of the Greenmachine I want to build.
The Gm is great - and about 5000 bux, with no support in North America.

I thought about dual suspension and whatnot. But that makes it heavier, more expensive, less efficient and complicated.
I wanted to make the frame very light.
Well just by isolating the rider, who weighs say 150 or so pounds from a bike that weights 20-30? pounds, on makes it both light (efficient) and fun (particularly with the seat).
I thought two parallel parallelogram thudbuster setups with a few inches of wiggle room by the frame on each side would suffice. Elastomer is adequate for non-winter cycling.
This does mean the seat must be free-floating. I.e. it is not leaning on the rear wheel assembly.

The square tube frame just makes my life easier. No concern that the seat can fall sideways!
A few holes or indents and the seat mounted on a sliding mount and the thing can adjust for rider height.
Of course (see the Optima Condor) below 5' 10" or so, 26" wheels become problematic.
There are 24 and 20" wheels about.

The chain is completely enclosed. No grease on yer work clothes. Pretty quiet.

The NuVinci drive is cheaper though heavier than an I-motion 9.
I suppose efficient favours the IM9, but I disliked the technical support.
The NVd is also easier in that it is a variable drive lacking discrete gears.

The SWB recumbent layout is amenable to a partial fairing and a motor assist if desired.
A backpack mount is a must! I'd like a Y-shaped shoulder mount on the back of the seat.
I don't like the idea of strapping a backpack to the luggage rack area. I always worry about those straps getting caught in the tires.

I could ride a 'bent the first weekend I tried it, so there is not much learning curve.
(Unlike a front-boom style - I still don't trust myself in traffic! ).

Well that is what I think a commuter bike should look like.
Other than the seat-suspension, the whole thing should be pretty simple to make.

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