How Do You Spread A Frame?

Discussion in 'Rack Mounted Engines' started by DougC, Jun 30, 2007.

  1. DougC

    DougC Guest

    (I put this here, since it mostly relates to the GEBE kit)
    I went looking through a couple cheapo tool stores today, for anything that could reliably bend apart the chainstays of the bike frame I have. The tubes are only about 3 inches apart, and none of the jacks or beefier screw-clamps (that could be used) would fit into such a tight area.

    I could make something I suppose, but I am wondering if there isn't some easy way I missed... The only method I could find was to get a cheapo farm jack (with a lot of farm jacks, you can set them up to function as fence pullers or spreaders). That arrangement might be able to reach inside three inches, but I am not even certain. The only size they had was about four feet tall.
    ~
     

  2. jerryt

    jerryt Guest

  3. DougC

    DougC Guest

    The Sheldon Brown method is no help, because it's dealing with the width at the rear axle. I don't need that, I need a bend in the seatstays about halfway down.

    The "squeezing a spot" business isn't gonna work either. The seatstays would have to be pushed out at least a quarter-inch, and the tubes are only about 5/8" as it is.

    The scissor jack won't work either, I'd bet.
    At one tool store, they didn't have "normal" scissor jacks, but they had a couple kinds of "electric" ones that had a motor on them and plugged into the cig lighter. The center of the scissor jack when folded completely down was still about 4-1/2" tall. And when the scissor jack is retracted it's got almost NO leverage.

    The shortest bottle jack I saw was about 8" tall retracted.

    I was thinking--maybe if a mcpherson spring compressor could be switched around, to pull outwards instead of compress normally, that might work....
    http://www.jcwhitney.com/autoparts/.../Ntk-AllTextSearchGroup?Ntt=spring+compressor
    ~
     
  4. special tool I dont have

    Park tools makes a special bender that will do offsets in the chainstays, one of my customers has one, tho I've never seen it. He says it works nicely,
    Mike
     
  5. bamabikeguy

    bamabikeguy Active Member

    There are three ways I've come up with to spread the forks, and ALL require holding the 8 inches (more or less) steady between the axle slots.

    2 - 4" bolts, 3 wingnuts to hold it in those slots, and a nut to connect them.

    (Also two washers I couldn't remember to bring from the shop at 2:30 am)

    [​IMG]

    [​IMG]

    Tighten this apperatus as the "axle substitute", so when you spread the forks, that space stays steady and constant.

    Best method is a jack, cheapest is to call friends with small Yugo type tires and ask to borrow the jack for a few minutes. Think of the cars that sit really low to the ground.

    You'll find one to fit after 4-5 attempts, they can even go to the trunk and measure the jack and call you back to make it easier. The one I have came off a Chevy Cavalier in a guys mini-junkyard out back of his house.

    When you do, measure up to the area you want to crimp/spread, and tape it to prevent scratching.

    When you put the jack in, put the bottom/base on the right side/chain sprocket side, and scissor toward the side that needs clearance. It will NOT take many turns to get the desired clearance.


    The second way is my vise grip squeeze, when dry fitting the wheel/spokering show you need JUST A SMIDGEON. Again, wrap the area with tape to prevent scratching. You get the vise grips snug, then screw it in one turn and crimp the area, then screw in one turn and crimp the area, and probably one more turn, crimp the area and you are done.

    But add another 1/2 inch top and bottom to the crimp, so it has a wider area than that spoke ring, and it fits first time.

    [​IMG]

    The thing to notice in that picture is the wider/stationary side of the vise grips face outward, the narrower moving side is doing the crimping.

    The third way involves a block of wood and 4 shims, with a hammer.

    Measure the distance between the forks, where you need to spread. Let's say it is 3 1/4 inches.

    Take a 2 x 4 to a table saw and shave it down to 3 1/16. Then put the shims in the spaces, and drive them in with the hammer. AGAIN TAPE THE AREA. About 10 good whacks on the shims will get you the desired width. This method is unweildy without a bike stand.

    Hope it works well, :grin: the Workman doesn't need a whole lot of spreading I don't think, but as long as you tape the area, nothing will look too bad, and you'll probably be the only one that knows it was done, it isn't very noticable.
     
  6. bamabikeguy

    bamabikeguy Active Member

    Oh, I forgot to mention, to make buying the apperatus components simple, carry along an axle nut to the hardware store, to get the right size the first time.

    Since everything varies a bit, that is why I have 3 wingnuts, so it can fit different widths.

    But if you buy bolts that are too narrow, it slips out of the axle slots. :???:
     
  7. bamabikeguy

    bamabikeguy Active Member

    Doug, one final thing about the Workman.....

    I was very impressed with the spokes, and the bike itself, so err on the side of caution installing the gear ring.

    You have to drill out the slots, you can take a heavy gauge plastic bottle (not coke bottle grade, more like liquid detergent grade) and drill test holes, try three drill bit sizes till you get the snuggest fit.

    [​IMG]

    Triple check your gap when you snap in 12 o'clock and 6 o'clock.

    The spokes are unforgiving, hold them firm when snapping on, so there is zero chance of bending one.

    Spin the notches around the spoke, there are definitely certain placements that are perfect, and certain ones where one or two spokes are off by 1/8 of an inch.

    Finish snapping, then you will still find one or two that need a smidgeon more to be perfectly snug.

    Also, GEBE recommends liquid detergent for lube, and I've also tried vegetable oil and 3-1 oil.

    Detergent is best because it washes off completely, while oil is sloppy and puts a film on the area where the brake shoes work.

    The warning on detergent is make sure you rinse it all off after completion, else rust forms where the notch fits the spoke.

    GOOD LUCK ON THE BIKE, you will have a winner when you are done !!!!
     
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