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  1. #1
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    Vintage stumpjumper SS conversion?

    I recently got a stumpjumper frame (believe it's '86 or '87) as a trade for some parts. I'd really like to build up a SS MTB but i'm not sure if this is a good candidate. My plan initially was to get a craig's list donor bike for cheap to get most of the parts.

    As i've researched it, though, there is a complication: The under the chain stay mounted rear U brake. from what i've read, they were a short lived fad in the '80's that didn't last mainly because they routinely got clogged with mud.

    Also, the previous owner apparently found it with the rear derailer hanger badly bent, and sawed it off. So, it has a semi horizontal dropout on the non-drive side and what amounts to a vertical dropout on the drive side (looks like a semi-horizontal filled in). So, i would either need to use a chain stay mounted chain tensioner or file the drive side dropout to make it semi-horizontal (which i'm not sure how it would effect the strength of the dropout).

    Given the issues, would it be better to stick with this frame or scrap the project and start looking on craig's list for something else?........will post some photos tomorrow.

  2. #2
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    since the hanger is already hacked off, its days as a geared bike are done. So I would have a go at making it a ss. File the dropout if there is plenty of metal. If you try a few different gear ratios you may find one that work with little or no filing anyway.
    crash expert, ss convert

  3. #3
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    If the drive side looks like a semi-horizontal "filled in", un-fill it.
    I had a '96 Stumpjumper that I modified the dropouts just enough to make them slightly semi-horizontal that would give me enough adjustment for a the life of a chain. I had to use a half link to get the tension perfect with my gear of choice.

  4. #4
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    i say go for it, you'll never know the outcome until you try

    i converted my '92 Kestrel CSX to SS and found the magical gear to be 36 X 16T which suits me fine for urban rides
    leave your car at home!

  5. #5
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    Thanks for the replies! So that answers one of the big questions. I was worried that un-filling the drop out would mess with the structural integrity, but it sounds possible. There is a good amount of metal filling it in, so there is a lot to work with.

    CB2, are you still running as a ss with your stumpjumper? if so, i'd love to see a pic.

    As you can see from these photos, there's a long way to go, but i'll be sure to post some photos of the completed build.
    Attached Thumbnails Attached Thumbnails Vintage stumpjumper SS conversion?-2011-11-17-19.09.19.jpg  

    Vintage stumpjumper SS conversion?-2011-11-17-19.09.56.jpg  

    Vintage stumpjumper SS conversion?-2011-11-17-19.10.20.jpg  


  6. #6
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    Quote Originally Posted by p nut View Post
    Yeah, drill that sucker out. That'd be a perfect SS candidate. And a pretty cool one at that. I had a 93 Hardrock that also had the horizontal drops with a metal tab in the middle. Not sure why Spec did that? Maybe cost, as they may have had a bunch of these dropouts on hand?
    when you say 'drill that sucker out,' do you mean actually use a standard drill bit? i was planning on using a dremmel and a hand file. is there a better way from people's experience?

    also, yeah, it seems weird to me to have a fully semi horizontal dropout on the non-drive side but what amounts to a vertical dropout on the drive side. i doubt specialized was foreseeing people filing out the dropout, so why do it?

  7. #7
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    Yeah, drill that sucker out. That'd be a perfect SS candidate. And a pretty cool one at that. I had a 93 Hardrock that also had the horizontal drops with a metal tab in the middle. Not sure why Spec did that? Maybe cost, as they may have had a bunch of these dropouts on hand?

  8. #8
    CB2
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    Quote Originally Posted by rjwall View Post
    when you say 'drill that sucker out,' do you mean actually use a standard drill bit? i was planning on using a dremmel and a hand file. is there a better way from people's experience?

    also, yeah, it seems weird to me to have a fully semi horizontal dropout on the non-drive side but what amounts to a vertical dropout on the drive side. i doubt specialized was foreseeing people filing out the dropout, so why do it?
    I'd probably use the dremel or a drill with a grinding bit.

    When that frame was made vertical drops were not the norm. The "filled in" dropout was probably an exciting new option to make it easier for people to center their wheel back in the day.

    Here's mine as a HT


    and rigid

  9. #9
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    Looks awesome! (also appreciate the jammin econo!) I'm pretty far away from tire selection, but what kendas are those? This was supposed to be my slow winter build, but now i'm excited to get it in the dirt ASAP!

  10. #10
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    Heres a link to my build
    http://forums.mtbr.com/singlespeed/8...er-728699.html
    Attached Thumbnails Attached Thumbnails Vintage stumpjumper SS conversion?-0914112056.jpg  


  11. #11
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    Quote Originally Posted by rjwall View Post
    Looks awesome! (also appreciate the jammin econo!) I'm pretty far away from tire selection, but what kendas are those? This was supposed to be my slow winter build, but now i'm excited to get it in the dirt ASAP!
    Those are Kenda Karmas. I liked them a lot in 26". Surprising amount of traction from such a minimal tread.

  12. #12
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    The first SS I built was my old XL 1990 Rockhopper. I hit the dropouts with a dremel and was able to run a 34x20 with no tensioner. Just took a little bit of work and I was able to ditch the singleator.

    Last edited by SeaBass_; 11-21-2011 at 07:45 AM.

  13. #13
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    Thanks all, just got home from work, grabbed a beer and am going to file the dropout. great looking builds!

    Beatniqwood09, awesome thread, got me inspired to get this build completed. great green color!

  14. #14
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    Those chainstay mounted brakes are bad A$$, i had a buddy who had an old trek that had the brakes mounted down there, thought it was the coolest thing in the world. I nearly forgot about that unfortunate fad... I think you need to bring this back to life and ride it with the brakes mounted on the chainstays.

    +Rep for rescuing a vintage.

  15. #15
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    Thanks for the advise everyone on drilling out the dropout. Got them down to normal semi horizontal dropouts.

    First pic: decided to drill out a couple holes to make for less filing.
    2nd pic: got partway through before my girlfriend stopped me for some non-MTB related friday night socializing.
    3rd pic: just about filed out dropout, needs a little clean up.

    .......now to choose the color and paint.
    Attached Thumbnails Attached Thumbnails Vintage stumpjumper SS conversion?-2011-11-18-17.17.55.jpg  

    Vintage stumpjumper SS conversion?-2011-11-18-17.53.25.jpg  

    Vintage stumpjumper SS conversion?-2011-11-20-16.22.39.jpg  


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