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  1. #1
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    Increasing dropout spread

    I have my eye on a trek 660 circa 1985. I will need to cold set the dropouts.
    Sheldon seems to be a fan of the 2x4, and another site advocates using all thread, nuts and washers with a crescent wrench and an alternative to this is to use a turn buckle to make sure that one turn is one turn.

    Then there is something about using string to align the frame?

    Can anyone shed some light on this mysterious process for me.

    Thanks

  2. #2
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    There's nothing too mysterious about the process. You have one basic objective which is to spread the dropouts equally on both sides so the wheel remains centered in the frame (assumes it started out centered).

    I'm not a fan at all of the turnbuckle method for a number of reasons. The main one is based on the physics of bending steel. Bending steel involves increasing stress to flex it until it reaches the yield point at which it will bend. You can demonstrate this principle with the spring from a cheap ballpoint pen. Pull it apart a bit and it springs back to the original length, but if you go too far it'll deform and it'll spring back to a longer length.

    Applying this to your bike and you'll you'll understand why I don't like the turnbuckle method. As you tighten the turnbuckle the frame will spring open fairly symmetrically because the chainstays are of similar strength. But once one side reaches it's yield point and begins to actually deform no more tension can be added so the second will never bend, and all the permanent distortion will be to one side, spoiling the symmetry.

    So you need to bend from one side at a time, carefully checking that you're only going half way. I use a method similar to what SB proposes. I make a gauge the width of the dropouts from an axle, or scrap of anything stiff I can cut to length. Then I bend one stay being careful to know which. You can use a 2x4 if you like or do as I do and lay the bike flat, and stand on one stay about half way to the BB, and lifting the other holding it from the end. The one I'm holding will bend will flex feeling increasingly "heavy" until I feel it begin to move, at which I stop and check with a gauge. With practice you can judge the amount of bend you create, but I expect you'll do it by degrees until you have half the spread. Then flip the bike and repeat for the second side.

    When finished you might check with the string method to see that the frame is aligned. Actually you might what to do a string test first, so if it isn't right you can align it at the same time as you spread it.

    This is actually very easy in practice and, unless you're mechanically declined, you shouldn't have any problem.

    BTW- I didn't look up your bike, but it has to be steel, otherwise none of the above applies.
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  3. #3
    bike whisperer Kimmo's Avatar
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    A nice touch is to make the dropouts parallel again afterwards with a crescent wrench. Can be done well enough by eye with care.

    Derailleur hanger will need realignment, particularly if using >8spd.

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    I've seen the spreading done with a bushing on each side of the bottom bracket and the frame held in the comfort zone by a large vise. It puts the chainstays right at shoulder level and there's quite a bit of control. It's cool. Can anyone tell me what the bracket/bushing thing is and where I can get one?
    thanks
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  5. #5
    Senior Member himespau's Avatar
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    I've used the method involving a long bit of threaded rod with washers and bolts the inside of each dropout and turning equal amounts (not sure that's really necessary, but that's what someone suggested. It worked for me, but was sort of a pain because, as FBinNY suggests, one side moved out further than the other. This meant I had to put the side that went out further down and put pressure on the seattube until the spacing was equal. Took several tries to get right. If I had it to do over again I would either have bought the 2x4 or paid the bike shop the $50 they wanted to do it, but the day I wanted to do it the bike shop was closed and I am car free so transporting a 3 ft length of threaded rod and some washers home from the hardware store was easier than a longer 2x4. Also, I got two pieces of threaded rod, so I could use them to align the dropouts when I was done. That worked ok.
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  6. #6
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    Quote Originally Posted by Rubato View Post
    I've seen the spreading done with a bushing on each side of the bottom bracket and the frame held in the comfort zone by a large vise. It puts the chainstays right at shoulder level and there's quite a bit of control. It's cool. Can anyone tell me what the bracket/bushing thing is and where I can get one?
    thanks
    This is definitely the hard way and offers little benefit. But if you like you don't need anything special. Simply use 2 big washers to protect the faces of the BB shell, or install old or scrap steel cups or cartridge lockrings in either side sticking out beyond the faces before clamping in the vise. I said old or scrap, because there's a decent chance of marring steel cups cosmetically, or damaging aluminum cups.

    This isn't complicated and doesn't need to be made so. If you wish to have more leverage or control then my lift from the floor method offers, put the 2x4 in a vise sticking out enough to reach the length of the chainstays to the BB. Slip the chainstays over the BB and bend to one side by pulling on the frame. If you like you can drive a nail into the side of the 2x4 down near the vise for the drop out to rest on to help keep the frame from slipping down.
    FB
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  7. #7
    Fail Boat crewman
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    So it sounds as if the 2x4 works the best, but then do you have to realign the dropout hanger for the rear d?

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    If you do the math, the change in angle for a 3mm spread is miniscule. This is why it isn't absolutely necessary to resquare the dropouts parallel, though I prefer to do so (but then again I have the tools necessary to do this correctly).

    Likewise with the RD hanger, if you have the tool go ahead and realign it, since it'll be off 4-6mm front to back over the diameter of the wheel (assuming it was right before). On the other hand, if it was OK before, then that error isn't enough to create any issues. In any case, if you have the tool needed to check and square a hanger it's always good practice to check it before mounting the RD, because you never know.
    FB
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    “Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

    “One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

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  9. #9
    coprolite fietsbob's Avatar
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    People have popped loose brake and chainstay bridges,
    ... if you tool up so as to restrict the spread there,

    so it happens just past that point,
    that would be smart.

  10. #10
    Constant tinkerer FastJake's Avatar
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    Are you just going from 126 to 130mm? If so you don't "have" to cold set and I have never bothered on this kind of change. It is easy enough to spread the dropouts when installing the rear wheel.
    Why "derailer" is the correct way to spell the gear-change mechanism: sheldonbrown.com/derailer.html

  11. #11
    Fail Boat crewman
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    I believe that it is a 4mm adjustment. I know that I do not "HAVE" to do it, but I like things done right. Plus how would this affect the bearing on the rear wheel if I did not spread it.

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    Quote Originally Posted by fietsbob View Post
    People have popped loose brake and chainstay bridges,
    ... if you tool up so as to restrict the spread there,

    so it happens just past that point,
    that would be smart.
    Some sort of clamping action to protect the welds seems like a good idea. But the amount of stress being applied here isn't that great. If they fail from bending the frame such a small amount, I think I might prefer they break in the shop than on the road.

  13. #13
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    Quote Originally Posted by I_like_cereal View Post
    I believe that it is a 4mm adjustment. I know that I do not "HAVE" to do it, but I like things done right. Plus how would this affect the bearing on the rear wheel if I did not spread it.
    The clamping pressure of the skewer is FAR far greater than the spring tension of a 126mm dropout being used on a 130mm axle.

  14. #14
    DRF aka Thrifty Bill wrk101's Avatar
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    Quote Originally Posted by I_like_cereal View Post
    I believe that it is a 4mm adjustment. I know that I do not "HAVE" to do it, but I like things done right. Plus how would this affect the bearing on the rear wheel if I did not spread it.
    No affect at all. 4mm (2mm per side), you are talking about 1/16 inch per side or so. I would not cold set, just squeeze it in (it will not take much).

  15. #15
    Fail Boat crewman
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    Quote Originally Posted by wrk101 View Post
    No affect at all. 4mm (2mm per side), you are talking about 1/16 inch per side or so. I would not cold set, just squeeze it in (it will not take much).
    If y'all agree with that then I will forgo the cold set. I would still need to reset the rear d hanger or is the spread to minimal to worry about?

  16. #16
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    I shoved my 130mm wheel into my rear dropouts that were around 124mm and didn't change anything else out other than the low and high limit screw settings for the derailleur since i went from a 6 speed freewheel to a 7 speed cassette. I didn't bother cold setting or anything. Works fine.

    I think you are rather overthinking this. Just relax, shove your new wheel in place and possibly adjust the limit screws and go ride.

  17. #17
    Fail Boat crewman
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    I always over think, plan, and do.

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  18. #18
    Senior Member gyozadude's Avatar
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    I've used Sheldon's posted 2x4 method recently on a somewhat skewed rear triangle on a Bianchi Limited 1988. It had 126mm dropout spacing that was warped just a couple of mm to the left. I spread the right about 3mm and the left about 1mm using a 2x4 about 6 ft long on the ground with some cardboard to protect the paint. Took about 8 iterations on the right side and 4 iterations on the left side to get it right. There is some elastic deformation you need to overcome. So you may need to flex a side 5mm to move it 1/2mm plastically. Each frame is different so play around at first.

    But after dropout and RD re-alignment by eyeball, I used tools borrowed from a neighbour and confirmed that eyeballing isn't far off at all. And quite acceptable for riding. The benefit from spreading to 130mm is the ease with which swapping wheels and installing hubs becomes. You don't get caught in the dilemma during wheel insertions and removals wondering if the QR is too tight or misaligned or if it's the RD and chain that isn't in the proper position because you forgot to shift to the smallest cog, etc that is preventing the proper seating of the axles. It's not a big benefit, but nice to have.
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    Y9ou have to be carefull because as somebody mentioned, the brake bridge or the bridge between the chainstays can pop out, saw it once.

    I have used two rods and with washers and bolts, one at each side then you go turning the bolts the same turns at both side. From 126 to 130 mm the rear end needs to spread around 150 to 160 but it depends on the steel also. Some reynolds is pretty easy to bend, the last bike i did was mine and had Columbus SL (all the tubes) and that one took me like 45 mins doing it really slow. The other thing I did was to put like a belt or a fabric type of cinch below the brake bridge just in case. A friend of mine used to put 2, on in the brake bridge area and the second one round mid chainstay just in case only.

    Good luck.

  20. #20
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    Quote Originally Posted by FastJake View Post
    Are you just going from 126 to 130mm? If so you don't "have" to cold set and I have never bothered on this kind of change. It is easy enough to spread the dropouts when installing the rear wheel.
    +1 Done a couple mid-late eightys 126 mm Treks. 130 wheels drop right in with minimal effort.
    '68 Raleigh Sprite, '02 Raleigh C500, '84 Raleigh Gran Prix, '91 Trek 400

  21. #21
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    Done it without 2*4 with good results;

    Take off shoes and socks.
    Sit on floor holding frame in front of you
    one hand on headtube, one hand on seattube, plant foot against farside chainstay
    push with foot to bend chainstay outwards
    -alternatly,
    hand on headtube, foot on seattube, other hand pulling nearside chainstay
    pull chainstay towards you

    use foot power for big adjustments, hand power for control
    be careful, biker legs are stronger than you think...

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