26/20 -) 26/26 conversion?

Discussion in 'Recumbent bicycles' started by Markku Poysti, Mar 7, 2003.

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  1. Has anybody tried to convert 26/20 recumbent into 26/26?

    Just tried putting about 7 cm of books under front wheel of my Vision R40 (LWB/USS), and noticed
    that my feet still reach the ground well enough. It should be rather easy to find cheap used MTB
    steel front fork and weld the small part needed for steering linkage.

    If that works, i get bottom bracket a few cm higher than seat, which i hope is better than the
    current 0 cm.

    It would be almost like the Vision "Saber", but in LWB.

    Also i don't have to deal with the 406 size problems. Studded tires easily available + good
    selection of summer tires.

    Also i hope that curbs, rocks and loose snow will be less of a problem.
     
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  2. Obento

    Obento Guest

    My last homebuilt (stratus clone -long wheel-base) ended up with 700/700 wheels ,which really rolls
    easily and handles well.I'm happy with it. Potential problems with your conversion are pedal
    clearance ,and wheel flop, depending on your fork. By adding trail(bending) to my 700 forks to get
    rid of flop,I solved the clearance problem at the same time(myBB is lower than your R40). Shorter
    cranks can also help with clearance. "Markku Poysti" <[email protected]_nospam> wrote in message
    news:[email protected]...
    > Has anybody tried to convert 26/20 recumbent into 26/26?
    >
    > Just tried putting about 7 cm of books under front wheel of my Vision R40 (LWB/USS), and noticed
    > that my feet still reach the ground well enough. It should be rather easy to find cheap used MTB
    > steel front fork and weld the small part needed for steering linkage.
    >
    > If that works, i get bottom bracket a few cm higher than seat, which i hope is better than the
    > current 0 cm.
    >
    > It would be almost like the Vision "Saber", but in LWB.
    >
    > Also i don't have to deal with the 406 size problems. Studded tires easily available + good
    > selection of summer tires.
    >
    > Also i hope that curbs, rocks and loose snow will be less of a problem.
     
  3. David

    David Guest

    [email protected]_nospam (Markku Poysti) wrote in message news:<[email protected]>...
    > Has anybody tried to convert 26/20 recumbent into 26/26? Just tried putting about 7 cm of books
    > under front wheel of my Vision R40 (LWB/USS), and noticed that my feet still reach the ground well
    > enough. It should be rather easy to find cheap used MTB steel front fork and weld the small part
    > needed for steering linkage.
    [snip]

    If you are intending to swap the 20" (406) front wheel to a 26" (559) you will raise the front end
    of your R40 by aprox 15cm. Judging by the photo on the website
    (http://www.visionrecumbents.com/Images/BikeBigR40EUMed.jpg) this would raise your seat height by
    aprox 11cm.
     
  4. >If you are intending to swap the 20" (406) front wheel to a 26" (559) you will raise the front end
    >of your R40 by aprox 15cm.

    Good point. But even with 15 cm under the front wheel, i could reach the ground with my feet.
    (I'm 170 cm)
     
  5. David

    David Guest

    [email protected] (David) wrote in message
    news:<[email protected]>...
    > [email protected]_nospam (Markku Poysti) wrote in message news:<[email protected]>...
    > > Has anybody tried to convert 26/20 recumbent into 26/26? Just tried putting about 7 cm of books
    > > under front wheel of my Vision R40 (LWB/USS), and noticed that my feet still reach the ground
    > > well enough. It should be rather easy to find cheap used MTB steel front fork and weld the small
    > > part needed for steering linkage.
    > [snip]
    >
    > If you are intending to swap the 20" (406) front wheel to a 26" (559) you will raise the front end
    > of your R40 by aprox 15cm. Judging by the photo on the website
    > (http://www.visionrecumbents.com/Images/BikeBigR40EUMed.jpg) this would raise your seat height by
    > aprox 11cm.

    doh...not 11cm...only 5cm seat raise..it was a long day :(
     
  6. M.T. Flaman

    M.T. Flaman Guest

    If a 26" front wheel replaces a 20" wheel, the front of the bike will be raised only 3" (or about
    7.5 cm) - not six inches. Accordingly, the seat itself would be raised only about 1 inch to 1.5
    inches, depending on the bike geometry.
     
  7. http://hepso.dna.fi/misc/2626.jpg

    Here is a picture of the 26/26 modified Vision.

    No clearance problems.

    There is some wheel flop, but i don't think it is a problem.
     
  8. Nice job!

    I just posted the same question about a week ago on BROL and received no responses.

    I sent an email to Vision asking the same question and they warned me to not make the conversion.
    This made me want to do it even more.

    Then I saw your post and the responses.

    I want to convert a SWB R40 to 26/26. I need to find an R40 first though. I have a Rocket and want
    at least a 26 inch rear wheel. The Rocket wheels can't be changed to anything that I know of.

    Markku Poysti <[email protected]_nospam> wrote in message news:[email protected]...
    > http://hepso.dna.fi/misc/2626.jpg
    >
    > Here is a picture of the 26/26 modified Vision.
    >
    > No clearance problems.
    >
    > There is some wheel flop, but i don't think it is a problem.
     
  9. On Sat, 08 Mar 2003 14:23:15 GMT, "M.T. Flaman" <[email protected]> wrote:

    >If a 26" front wheel replaces a 20" wheel, the front of the bike will be raised only 3" (or about
    >7.5 cm) - not six inches.

    That's assuming you can use the same fork, which seems unlikely. If you use a longer fork to
    accomodate the larger wheel, the front will raised by 6".

    Ken Kobayashi [email protected] http://solarwww.mtk.nao.ac.jp/kobayashi/personal/
     
  10. Pete Huber

    Pete Huber Guest

    I converted a Speed Ross using a carbon fiber 650 fork and a 26" wheel. Biggest problem was
    reworking the brake to avoid conflict with the frame. Bike rides better than before.

    Pete Huber Speed Ross Pulaski, VA

    "Markku Poysti" <[email protected]_nospam> wrote in message news:[email protected]...
    > Has anybody tried to convert 26/20 recumbent into 26/26?
    >
    > Just tried putting about 7 cm of books under front wheel of my Vision R40 (LWB/USS), and noticed
    > that my feet still reach the ground well enough. It should be rather easy to find cheap used MTB
    > steel front fork and weld the small part needed for steering linkage.
    >
    > If that works, i get bottom bracket a few cm higher than seat, which i hope is better than the
    > current 0 cm.
    >
    > It would be almost like the Vision "Saber", but in LWB.
    >
    > Also i don't have to deal with the 406 size problems. Studded tires easily available + good
    > selection of summer tires.
    >
    > Also i hope that curbs, rocks and loose snow will be less of a problem.
     
  11. R2D2

    R2D2 New Member

    Joined:
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    Great idea Markuu. You'll be faster, smoother, and more aerodynamic.

    Ken Kobayashi wrote:
    >That's assuming you can use the same fork, which seems unlikely. If you use a longer fork to
    accomodate the larger wheel, the front will raised by 6".

    Ken/David are pretty close with their numbers, although the head tube angle and fork rake will combine to reduce these numbers a little.

    Be aware that your head tube angle will slacken quite a bit with the new larger fork/wheel. Depending on the handling characteristics of your current setup, you should determine your necessary fork rake appropriately, as your trail will be increasing substantially.

    Like Obento says, trail will be so great that "wheel flop" will become a problem. :eek:

    You may end up changing (rewelding) the angle of your head tube to compensate.

    Have fun with the project!
    R2
     
  12. Mark Stonich

    Mark Stonich Guest

    "Robert Riggins" <[email protected]> wrote in message
    > I want to convert a SWB R40 to 26/26. I need to find an R40 first though. I have a Rocket and want
    > at least a 26 inch rear wheel. The Rocket wheels can't be changed to anything that I know of.

    I'm not sure if this applies to all Rockets, but the newer ones, with the 2" main tube are easily
    converted to 26" rear wheel.

    There was a thread here a few months ago about doing so on a Tailwind, which uses the same rear
    stays. I believe all they had to do was move the bridge between the lower stays. I think they
    mounted a sidepull on the bridge, but it wouldn't be hard to add new canti pivots.

    If you're up to a little frame hacking, it wouldn't be hard to make a
    26/20 Rocket that didn't raise the seat.
     
  13. I unfortunately have the 2000 model and have tried a 559. It's not even close. The rear end of the
    main tube is the limiter. I would need longer stays. That becomes a bit more work than I want.

    Thanks, Rob

    Mark Stonich <[email protected]> wrote in message
    news:[email protected]...
    > "Robert Riggins" <[email protected]> wrote in message
    > > I want to convert a SWB R40 to 26/26. I need to find an R40 first
    though. I
    > > have a Rocket and want at least a 26 inch rear wheel. The Rocket wheels can't be changed to
    > > anything that I know of.
    >
    > I'm not sure if this applies to all Rockets, but the newer ones, with the 2" main tube are easily
    > converted to 26" rear wheel.
    >
    > There was a thread here a few months ago about doing so on a Tailwind, which uses the same rear
    > stays. I believe all they had to do was move the bridge between the lower stays. I think they
    > mounted a sidepull on the bridge, but it wouldn't be hard to add new canti pivots.
    >
    > If you're up to a little frame hacking, it wouldn't be hard to make a
    > 26/20 Rocket that didn't raise the seat.
     
  14. On 10 Mar 2003 01:31:42 +1050, R2D2 <[email protected]> wrote:

    >Ken Kobayashi wrote:
    >>That's assuming you can use the same fork, which seems unlikely. If you use a longer fork to
    >accomodate the larger wheel, the front will raised by 6".
    >
    >Ken/David are pretty close with their numbers, although the head tube angle and fork rake will
    >combine to reduce these numbers a little.

    The 6" figure was a first-order approximation. ;-) Actual number would depend on the forks.

    >Like Obento says, trail will be so great that "wheel flop" will become a problem. :eek: You may end
    >up changing (rewelding) the angle of your head tube to compensate.

    Wouldn't it be easier to re-weld the fork to increase the rake? I wonder if you could just bend
    the fork...

    Ken Kobayashi [email protected] http://solarwww.mtk.nao.ac.jp/kobayashi/personal/
     
  15. R2D2

    R2D2 New Member

    Joined:
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    Ken wrote:
    >Wouldn't it be easier to re-weld the fork to increase the rake? I wonder if you could just bend the fork...

    You are right-on Ken. (And I didn't do the geometry either, but your 6 inches was Very close :) )

    Bending the fork to increase the rake would be a given, as Obento mentioned. However there is a good chance that the increase may not be enough, and changing the head tube angle may be necessary. It all depends on how it steers once put back together.

    Hmm, I wonder if using a 700c or 27" fork would give you enough real estate... You may not even have to reweld the brake bosses when done.

    Just a thought. I've never actually done a conversion, but have welded them from the ground up.
     
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