converting vintage frame to modern mountainbike

Discussion in 'HOW TO' started by harquahalas, Mar 10, 2011.

  1. harquahalas

    harquahalas

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    I've got a 50s Schwinn straight bar frame and I'm thinking of converting it to mountain bike. Any ideas on the rear derailleur? Maybe a Nexus 8 speed, but I don't how the gear ratios would be and if it will allow for the angles of a front 3-piece crank. You guys think the frame would be strong enough? Any other potential problems I'm not thinking of? I would want to use this for real trail mountain biking.
  2. TheFlyingDingo

    TheFlyingDingo

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    In my opinion, those older frames are too flexy. The "Nope" I had (just sold it today) Flexed way too much cranking down the road. Im not sure how much different straight bars are from cantilevers.

    I noticed most flexing was as the bottom bracket/seat tube. But I am a heavy guy.

    As of deraulelelrler...(sp)

    I suppose you could use the bolt on hanger, and hang a more modern Deraulelerlala
  3. scrumblero

    scrumblero

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    a bunch of guys do that here in norcal, disk brake forks and a drum on the back with modern drivetrain. you just gotta figure out your chainline .
  4. harquahalas

    harquahalas

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    Figure out my drivetrain? Should I do a drum brake internal gear hub? What about my bracket sizes? Are there parts made that will fit or adapters?
  5. aka_locojoe

    aka_locojoe

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    I've thought of this too. More of a trail bike I suppose. Never could decide what the best setup would be.
  6. Bendix

    Bendix

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  7. harquahalas

    harquahalas

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    I'm not sure, but I don't think a clunker is what I'm really going for. I want to use newer parts, like XT components and Rock Shox forks. Maybe it's just not something that will work :?
  8. Sinner4

    Sinner4

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    45' Elgin, front suspension, I could use a disk front brake, alloy bars, S/A 3 speed laced to a modern alloy rim, 3 piece crank now in place. A hoop off a front shock welded to the seat stay for a modern v pull rear brake. All Modern stuff. Older picts, been ever changing the lay out of the stuff.

    [​IMG]
    [​IMG]
  9. harquahalas

    harquahalas

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    Hey Sinner, is that a 1 1/8" threadless fork and if so, how did you fit it?
  10. Sinner4

    Sinner4

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    Well the head tube is pretty much a standard size. Found the stuff at the Bike co-op here in Boise BBP. Found the right cup size, pressed in and instant up grade. Nothing to it.
  11. deorman

    deorman

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    While it's certainly possible, rear entry dropouts don't really lend themselves well to the use of "cog-swappers". :|
  12. deorman

    deorman

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    There's always internal gear hubs. 8)
  13. Beau

    Beau

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    On older frames, with the larger 1" headtube, you can use the factory cup with a mix of 1 1/8" headset parts and loose ball with 1/8" balls. You will need to have a few headsets for parts though and a bit of trial and error. You can squeeze 1 1/8" cup in to the frame, but it will ruin the head tube.

    The frame can be cold set to run a cassette hub, and you will also have to narrow the axle a bit to fit the smaller rear dropouts.

    There are adapters made by Problem Solvers that will allow you to run a derailleur that doesn't have a hanger in back.

    Any shop can order you an American to Euro bottom bracket, or you can run a BB that will convert from American to a JIS square taper. Otherwise a BMX crank with with a Profile adapter will allow you to also run a front derailleur with a double or triple. Chainline won't be a problem with BMX cranks though.

    DON"T run canti/linear brakes on back. I don't care what anyone here says, the frame will flex really bad with those brakes. It was not designed for those load (unless you run a booster or brace the frame). If you run an internal hub, the drum is a great idea. Otherwise, disk mounts with a 160mm rotor can work with proper bracing on the frame.

    Now here is the problem. Old frames were not used to having stiff parts on them or the stresses that modern parts provide. The headtube can "stretch" or flare if you run a long travel fork (and mess up the geometry REALLY bad). I have also flared out bottom brackets with stiff BMX cranks.

    No matter what, I encourage a build because it's pure fun and I love the look of old school bikes with modern parts. But in the end, you will have a noodle of a bike that really isn't that safe.

    If you want the look of an old school bike, with a MTB geometry, look for a 1999 Schwinn Panther or a 2002 Trek Clyde or the Van Dessel line. I have the Clyde and it's an awesome bike that has a cruiser look, but will actually perform. I'm still on the hunt for the elusive Panther though.

    :)
  14. harquahalas

    harquahalas

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    Thanks Beau. That's some solid info. I think I might just get myself a complete modern 29er, the ride is going to be a bit more important than the look for this one. Thanks all for the great tips. :D
  15. Beau

    Beau

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    Lynskey Cruiser 29er is AWESOME

    Ti frame and tons of money, but beautiful

    [​IMG]
  16. OctopusHook

    OctopusHook

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    Hey there harquahalas, I think i can help! I just converted an old cruiser frame to a mounten bike! I used a threadless Rock Shox Judy fork but to get the new headset cups to fit I had to ream out the head tube with a file. I also added reinforcing bands around the ends of the head tube to make up for metal I removed (although it wasn't much). I also used a Shamano 3 piece bottom bracket with an adapter. I explain the rest in the thread I started about it.
    Check it out. And let me know If you have any questions, I'd be glad to help!
    Cheers,
    Nate
    viewtopic.php?f=21&t=37542
    [​IMG]
  17. Dr. Tankenstein

    Dr. Tankenstein

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    Dude,
    That thing is a BEAST! It ROCKS!

    [​IMG]

    Cheers,
    Dr. T
  18. socal_jack

    socal_jack

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    Trek Sawyer frames are starting to show up on ebay, nice, heavy steel frame with a cruiser look in 29er. The bike itself is pretty expensive for such a crappy spec list, not sure why anyone would strip and sell the frame.
  19. deorman

    deorman

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    Well, it seems I lost track of which thread I saw what on here :roll: :oops: :? Anyway, if you just want to be able to ride (not push :p ) over hill and dale, through the woods and across the creek, old middleweight Schwinn bikes work just fine.If you're looking for air time or extreme slope riding, it (and/or you) is likely to get bent/broken. The old bolt-on hangers will take many quality derailleurs and mount on your dropout just fine. A 5 or six gear cluster will be much easier to fit between the dropouts than 8. Without seeing the bike in question, a larger problem on a fifties bike is the lack of provision for rim brake mounting at the seat stays. You can snag a steel fork bridge off of a cheap mtb and weld or clamp it on, spreading the stress over a larger area than welded on canti posts. There are some other fab and bolt-on solutions scattered around here, I think there's a couple in the last build off. :)
  20. deorman

    deorman

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    Obligitory shameless pic post :mrgreen:

    [​IMG]

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