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  1. #1
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    Folding Bike Frame Specifcations

    One of the things I would like to see here is a thread showing actual bike measurements so I can make a guess as to how I might fit on them. Here is a sample of what I would find useful for my 2006 1/2 Downtube VIIIH. Aluminum alloy frame, stock Kenda Kwest 65 psi tires (40x406///20x1.5 front, 47x406///20x1.75 rear) This is the stock bike setup before I made modifications.


    Here are the metric conversions. Both measurements are approximate, good to about 3mm.

    10 3/4" = 275mm, 13" = 330mm, 16" = 405mm, 22" = 560mm, 23 3/4" = 605mm, 40" = 1015mm, 41 1/2" = 1055 mm

    The Dahon site seems pretty good about posting frame geometry, but Downtube doesn't and I keep trying to guess if I could fit on a Mini. Don't have a clue about how I would do with a Brompton, Raleigh 20, Swift, etc.

    I would like to encourage others to post similar pictures or even just a list of measurements. Folders are a problem because standard measurements like seat tube and top tube measurements don't really apply.
    Last edited by Pine Cone; 04-17-07 at 04:45 PM.

  2. #2
    Senior Member caotropheus's Avatar
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    In mm the sizing would be much more clear !

  3. #3
    cyclist
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    rock on... Thanks for that pic. Unfortunately for my wife (and our bank account), the 23 inch reach is the same as my road bike.
    Scott

  4. #4
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    Bump this back up...

    Can't somebody add some frame measurement data about DT Mini, Raleigh 20, Brompton, Merc, Strida, Bike Friday, Dahon, Swift or ??? For anyone wondering if they will fit on bike X a standarized set of measurements would make it much easier.

    Wheel base and effective top and seat tube measurements would be the most useful. I don't care if they are metric or english or furlongs. If you don't want to post a pix then just post the numbers.

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    I think this is a great idea, and would also be interested in seeing parts measurements (like seat post diameter), and degree measurements for important frame angles (stem/seatpost)

  6. #6
    Prefers Cicero cooker's Avatar
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    I think the effective top tube measurement would be more than 23 3/4", if you measured horizontally.
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  7. #7
    Raleigh20 PugFixie, Merc LittlePixel's Avatar
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    Would have replied to this earlier but have just moved house and have had no internets till today...

    I posted a R20 BikeCAD file on here a while ago that fulfills what you ask though you need to go to the free JAVA viewer/authoring tool over at Bikeforest to view it; But seeing as how the threads search seems to be down, I can't resist this sort of thing. Strangely - this twenty only has one strut between top tube and the seattube - kinda like the 'new' one...


  8. #8
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    "I think the effective top tube measurement would be more than 23 3/4", if you measured horizontally."

    Might be. That's why I decided to show the picture of where I measured. The other minor problem is whether measurements are center-to-center, center-to-edge, edge-to-edge, etc. Most of my measurements are either center-to-center or center-to edge, depending on what seemed to make sense. What I have shown here is a reasonable, rounded off guess, accurate to about 0.25 inches or 5mm. Lots of these measurements will vary 5mm or more depending on tire size and brand, exactly where the rear wheel is placed in any bike with horizontal dropouts, etc. Since there is no data out there on most folding bikes I thought I would try and start the discussion off with an example.

    Additional refinement is more than welcome!
    Last edited by Pine Cone; 04-17-07 at 05:41 PM.

  9. #9
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    From other posts on this forum...

    Brompton S2L-X - 41.3" wheelbase (105 cm)

    Dahon Curve D3 - 37"/940mm wheelbase
    Dahon Mu SL - 40.2" wheelbase (102 cm)

    Downtube IX - 42.5"/1040mm wheelbase
    Downtube Mini - 37.5"/952.5mm wheelbase
    Downtube VIIIH - 41.5"/1055mm wheelbase

    Kent Ultralight 35.5"/900 mm wheelbase

    Mobiky Genius - 38.2" wheelbase (97 cm)

    Moulton F - 44"/1118mm wheelbase

    Raleigh 20 - 39.5"/1003mm wheelbase

    Sinclair A-Bike - 29.1" wheelbase (74 cm)

    Strida 35.5"/900 mm wheelbase

    Swift 41"/1040mm wheelbase


    From a post by DaFriMon on the Dahon Curve

    I'm 5' 7", so can't help you there, but I did take some measurements that might give you an idea. I put the both the stem and the seatpost and the max height mark and measured the distance to the floor. Saddle (Brooks B67) 40 inches, top of handlebar, 38 inches to the floor. Saddle (from center of seatpost) to center of handlebars, 25.5 inches. Of course, I put both of these much lower for myself. Please take these measurements as rough approximations, but I hope it helps. I suspect a taller person might feel a little cramped, but I don't know. Not my problem.
    Last edited by Pine Cone; 05-10-07 at 10:26 AM.

  10. #10
    Edd
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    Pine Cone
    I find it interesting that my Moulton F frame has a wheel base of 44". I read some where that this long wheel base took into account the small wheel size. I certainly find it a very good ride in comparison to Birdy, Brompton and Westwood.

    When I restored it whith a 'dual drive' I had to add 6" of extra chain to a new ultegra 9 speed chain!

    Edd

  11. #11
    jur
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    My R20 has a 28.6mm seat post, unlike lp's post.
    My folding bike photo essays www.dekter.net/

  12. #12
    Part-time epistemologist invisiblehand's Avatar
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    From pages ~16-17 in the Downtube thread ...

    .....

    Center of stem to center of seatpost is 21.5". Middle of the stem is 36" high. Saddle is 37" high

    Thanks,
    Yan

    .....

    jasong ---as best I can tell, eyeballing it with a tape measure, the distance from the center of the bottom crank to the top of the seat is 28 1/4 inches with the seat post at the safety mark.

    .....

  13. #13
    Part-time epistemologist invisiblehand's Avatar
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    Oh ... in an e-mail from Yan, he writes that all of the minis now have a seatpost diameter of 27.2

    -G

  14. #14
    rhm
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    Here's some dimensions off my Strida. Note the seat is adjustable; as it gets higher, it comes forward. So this one is set up for someone 6' tall, 32" pant size.

    1. Handlebar is 42.8" from the floor.
    2. Tip of saddle is 13.5" behind the handlebar.
    3. Saddle rails are 33" from the floor.
    4. BB is 10.7" from the floor.
    5. BB is about 17.5" from the center of the rear wheel. This was a little tricky to measure.
    6. Wheel base is 35.5"

    My apologies for the inches; don't have a metric tape measure in my office. The blue stuff is reflective tape.
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    rhm
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    Quote Originally Posted by Pine Cone
    From other posts on this forum...

    Dahon Curve - 37" wheelbase
    Downtube IX - 42.5" wheelbase
    Downtube Mini - 37.5" wheelbase
    Downtube VIIIH - 41.5" wheelbase
    Moulton F - 44" wheelbase
    Raleigh 20 - 39.5" wheelbase
    Swift 41" wheelbase
    Strida 35.5" wheelbase
    And according to A to B magazine (August 2006):

    Mobiky Genius - 38.2" wheelbase (97 cm)
    Sinclair A-Bike - 29.1" wheelbase (74 cm)
    Brompton S2L-X - 41.3" wheelbase (105 cm)
    Dahon Mu SL - 40.2" wheelbase (102 cm)
    Last edited by rhm; 05-09-07 at 08:15 AM.

  16. #16
    rhm
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    Here's similar data on my (somewhat customized) Kent cheapie. The posting of this photo is in no way intended to serve as an endorsement, recommendation, or approval of the bike in question, though I did ride it to work today.

    I would very much appreciate similar data on (nominally) similar bikes, especially the Dahon Curve and Downtube Mini.
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  17. #17
    willzz
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    i think on the R-20 the seatpost is 28.6mm
    but if you use a 27.2 and tighten the clamp then you can use the suspension 27.2 seatpost..
    that's... what i see others use ....on their R-20's

  18. #18
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    Quote Originally Posted by willzz
    i think on the R-20 the seatpost is 28.6mm
    but if you use a 27.2 and tighten the clamp then you can use the suspension 27.2 seatpost..
    that's... what i see others use ....on their R-20's
    I would reccomend spending the extra $3-4 and getting a 27.2-28.6 shim. It takes out any possibility of eventual failure that can happen withh that extra little bit of room in the frame between the seatpost and the outer frame tubing. That's what I did,

    Juan

  19. #19
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    Quote Originally Posted by rhm
    I would very much appreciate similar data on (nominally) similar bikes, especially the Dahon Curve and Downtube Mini.
    Here is some information on my Curve D3. The seatpost is not standard issue. Both the seatpost and the handlebars are inserted at their maximum recommended level. The 11.5" is from the crank arm connector to the ground, which is not clear in my photo. It looks like I may have measured to the pedal.


  20. #20
    Bromptonaut 14R's Avatar
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    My Dahon Curve D3 is almost identical to MequoJim's (including the Thudbuster), I just rotated the handlebar to increase the 24.5" distance between seat and hand reach.


    14R

  21. #21
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    Here are some specs for my 2006 Carryme with everything at full extension. When I say, "center top of saddle" I mean where the seat tube line crosses the saddle surface.

    Permanent measurements:
    Wheelbase- 29.5"
    BB height- 10"

    Stock configuration measurements:
    Distance from center of handlebars to center top of saddle- 20.5" (handlebars and top of saddle are at the same height so this is also the horizontal distance)
    Distance from left pedal nut in 9 o'clock position to center top of saddle- 31"
    Distance from bottom of saddle to rear rack- 22" (back of saddle is directly over rear rack, so this is also the vertical distance. forget a saddle bag...you can put a whole suitcase under your saddle!)
    Crank length- 170mm (6.69")

    If you want to replace handlebar stem (the piece shaped like a 7), cranks, and/or saddle:
    Center of BB to center of saddle rail bracket- 25"
    Distance from top of stem riser to center of saddle rail bracket- 17" (these are at the same height so this is also the horizontal distance...I believe this would be called the effective toptube length)

    As with most folders with angled seat tubes and stem risers, replacing replace the seat tube and/or stem riser with longer ones can increase both horizontal and vertical distances, but of course if these are too long then you might get excessive flex.

    2007 Carryme has had some design changes. I don't know if any of these measurements are affected.

    Sorry I'm too lazy to photoshop and picture.

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