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Old 07-23-07, 06:37 PM   #1
makeinu
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fold-in-half frames and seatpost removal

I recently discovered that my Downtube can be folded significantly smaller by removing the seatpost and inserting it between the wheels, parallel to the length of the frame.

That the seatpost runs perpendicular to the folded bike's longest dimension seems to be a common flaw among all fold-in-half frame designs. For example, I've attached a picture of the Dahon Curve along with a picture illustrating what it would look like if you removed the seatpost and wedged it parallel to the rest of the bike. The resulting shape is significantly smaller, perhaps even smaller than the Brompton (comparison pic also attached).

The only drawbacks seem to be that:
1. You have to remove the seatpost. (However, I find that, in practice, this isn't any more trouble than lowering the seatpost. You just don't get the same satisfaction of not having to detach anything. )
2. You can't actually stand the bike up this way; At least not Dahons, Downtubes don't depend on the seatpost to stand while folded. (Although it might be possible to stand the bike upright on a nice big rear rack.)

Other than that I think it's a great way to reduce the size of fold-in-half-frame bikes.

Comments?
Attached Images
File Type: jpg curved31.jpg (38.9 KB, 38 views)
File Type: jpg curved32.jpg (91.1 KB, 27 views)
File Type: jpg bromp_curv_comp.JPG (72.4 KB, 41 views)

Last edited by makeinu; 07-23-07 at 07:02 PM.
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Old 07-23-07, 10:43 PM   #2
lee_rimar
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Interesting , Now take it a step in the other direction - not necessarily the SMALLEST package, but one that's easy to move around with. Add some alternate way to attach the removed seat post to the frame and use it as a "handle." Then you could walk/roll the bike like a pram (Strida-style) instead of carrying it.

Forgive the amazingly poor edit on the already rough image posted earlier; hope it clarifies what I'm saying...
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Old 07-27-07, 05:11 PM   #3
makeinu
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So, no comments from Curve owners?
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Old 07-27-07, 06:38 PM   #4
Dahon.Steve
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Originally Posted by lee_rimar View Post
Interesting , Now take it a step in the other direction - not necessarily the SMALLEST package, but one that's easy to move around with. Add some alternate way to attach the removed seat post to the frame and use it as a "handle." Then you could walk/roll the bike like a pram (Strida-style) instead of carrying it.

Forgive the amazingly poor edit on the already rough image posted earlier; hope it clarifies what I'm saying...

I wish you could carry the bike like that but the rear hub will not allow it as the peddals will start moving and stop once they make contact with the frame. A shame.
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Old 07-27-07, 06:52 PM   #5
makeinu
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I wish you could carry the bike like that but the rear hub will not allow it as the peddals will start moving and stop once they make contact with the frame. A shame.
Wouldn't that depend on which way you push it? If you push it such that you engage the freewheel then the pedals won't move. Of course, I found the Curve to be somewhat troublesome to roll with the handlebars between the wheels.

Anywho, perhaps next gear* Dahon will grace us with a 15 pound design (though I doubt it, from the dahon forum it looks like they're going to copy the mini by releasing a heavier bike with an 8-speed hub.....why they'd still call it "SL" is beyond me).

*year (I actually caught this typo before hitting the reply button, but I decided it was so appropriate I would leave it )
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Old 07-28-07, 04:23 PM   #6
Dahon.Steve
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Originally Posted by makeinu View Post
Wouldn't that depend on which way you push it? If you push it such that you engage the freewheel then the pedals won't move. Of course, I found the Curve to be somewhat troublesome to roll with the handlebars between the wheels.

Anywho, perhaps next gear* Dahon will grace us with a 15 pound design (though I doubt it, from the dahon forum it looks like they're going to copy the mini by releasing a heavier bike with an 8-speed hub.....why they'd still call it "SL" is beyond me).

*year (I actually caught this typo before hitting the reply button, but I decided it was so appropriate I would leave it )
You're right, it does work!! I have the old Presto with Sram Spectro 3 and coaster brake and it will roll forward but not in reverse due to the coaster. It will also not go in reverse with my Dahon Vitessee a 5 speed Sturmey Archer hub. I suspect those with freewheels will have no issues.
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