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straighten a frame

Old 01-23-21, 02:07 PM
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straighten a frame

So this is the first time I have come across a frame that was out of alignment like this.



The whole rear triangle is pushed about 6-7mm over towards the non-drive side. Dropouts are aligned, and spacing (120mm) is correct between the dropouts. No signs of any bends or deformation in the tubes. This is pretty evident with the rear wheel installed.

Ok so how do I fix this? Clearly I need to bend the rear triangle back towards the drive side and I can imagine a bunch of ways to do that but would value input. I've looked at the stuff on the Park website but any other pointers?

Oh this is a Motobecane Le Champion frame made of Reynolds 531 from about 1974.
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Old 01-23-21, 02:28 PM
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-----

1 remove the bottom bracket asssembly including fixed cup

2 clamp shell in beefy bench vise

3 with shell tightly clamped you have both hands free to do the cold setting

4 use the palm of one hand to push the dropout in the desired direction
the steel has a measure of springiness and will come back toward where it was when released so one needs to take things slightly past where one wants them to end up

5 when you are satisfied you have it correct from the evidence of the string test remove the frame from the vise and place in repair stand, use the shell faces to make a verification check with the aid of a straightedge

the string and strightedge tests should agree. if they do not then a problem resides elsewhere, such as the seat tube and/or down tube not being perpendicular to the shell for example.

-----

Last edited by juvela; 01-23-21 at 04:40 PM. Reason: addition for clarity
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Old 01-23-21, 02:29 PM
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Signing on as I have a frame out of alignment like this as well with the rear triangle pushed to one side but the spacing is correct and drop outs aligned. With my bike the rear triangle has been respaced from 120 to 126 OLD and my guess is that whoever respaced the rear triangle just did a shoddy job of it.
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Old 01-23-21, 02:38 PM
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I would verify that the head and seat tube are in plane. And the front end of the bike is not off as don't move things where you do not need to.
A crude way would be to remove the bottom bracket and using the faces of that depending on tools available measure back, clamping the shell in a bench vise with a pair of 1-2-3 blocks on either side and a framing square or two set against them will get you in verify mode.
I would set a framing square edge against the seat stays and explore if they have a tale to tell.

I am assuming this is a bike without its full history known to you.

The 100 pt solution is a surface plate table and a "whipping" post.

Last edited by repechage; 01-23-21 at 02:48 PM.
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Old 01-23-21, 02:38 PM
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Frame alignment

My 76 Motobecane Champion Team was also bent out of alignment like yours, not quite as far though. I clamped the bottom bracket in a vise between two pieces of 1 x 4 pine to protect it. Then I just slowly pushed and pulled the frame back into alignment. At first I tried the method that uses 2 x 4 placed on the inside of the dropout and braced against downtube. This didn't sems safe in practice because it takes Lot of force to move the stats and I was worried about damaging the seat tube. I ended up just grabbing the dropout and forcing it with my bare hands. I had much better control. Do a good shove, check progress, adjust force accordingly. I did use a Park frame alignment tooll as went. When I wa a finished pushing and pulling the stays, I finished with dropout alignment using the Park tools
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Old 01-23-21, 02:38 PM
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Sheldon Brown has a method (doesn't he always)? You can get it reasonably straight and rideable that way.

Better yet is to clamp the bare frame in a beefy vise and do the work like that with the string method.

Better yet is to use a Park Frame Alignment Gauge, which will be more accurate than a string. I was able to salvage a fairly bent Zeus frame like this.

Best is to take it to a framebuilder with an alignment table if you want to get it dead on.

Your Le Champion is a 531 frame, which are pretty tough and can usually be bent back into shape with no discernable strength loss. Seeing your list of bikes, I'm guessing you'll want to take the time and perhaps $$ to get it as straight as possible?
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Old 01-23-21, 02:40 PM
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BlueDevil68,
By whole rear triangle, I suppose you mean both sides...if so, I would secure a block between the drops and nudge both at the same time.
Best, Ben
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Old 01-23-21, 02:55 PM
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Tools needed to center stays - six foot long 2 x 4 lumber, Fishing line or really fine string. Measuring tape.

Once you have decided which way to bend the stays, do so but be careful at brazed or soldered joints. I always put something to add strength to the chain stay brace area near the bottom bracket.

Attach the string to the non-drive side of the rear drop (use a fender eye, for example). Run the string up to and around the front of the head tube. Tie the running end of the string (temporary knot) to the drive side drop fender eyelet. Make sure the string is tight with no sag...



Measure the distance from the non-drive side of the seat tube to the string - be as accurate as you can be. Repeat for the other side and compare. Using the piece of lumber, as pictured, carefully bend one stay at a time in the direction it should go. Check with the string again. The results will tell you that you need to bend more or bend back a bit (try to avoid the bend back issue to avoid work hardening the metal). Check the drop distance and adjust as required. Repeat until the seat tube to string measurement is equal on both sides. That should get you centered.

Next, make sure that your drops are 120 mm apart and then square them up to each other. That should get you where you want to go.
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Old 01-23-21, 03:52 PM
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Thanks!!!

Yes both sides are moved over. Spacing is correct and dropouts are aligned so I suspect it happened with a rear wheel in the dropouts (or was built that way?).

No I have no idea of history. This will likely be a flip but my goal is to always sell things on in as perfect condition as I can make them so I do want it to be in good if not perfect alignment. My usual process involves aligning dropouts and rd hanger. This was the first frame I have found that was out of alignment like this enough that I thought it needed to be corrected.

I will check other frame geometry as well as I can before proceeding.
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Old 01-23-21, 05:56 PM
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Just a thought, and maybe someone has mentioned it already, but consider using threaded rod with bolts and washers on both sides of the dropouts while the correcting alignment. That will keep the dropouts fairly aligned and the spacing correct. Keep an eye on the seat stay at the brake bridge and seat tube. Unfortunately, if you see something bad it's probably too late

When I flipped bikes,I too, tried to align things properly before they went out the door. The Park tool that we can't call by name really helps. So much easier and more accurate than string. It pays for itself in time by the second use.

Good luck.
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Old 01-23-21, 06:11 PM
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Originally Posted by BlueDevil63 View Post
Thanks!!!

Yes both sides are moved over. Spacing is correct and dropouts are aligned so I suspect it happened with a rear wheel in the dropouts (or was built that way?).

No I have no idea of history. This will likely be a flip but my goal is to always sell things on in as perfect condition as I can make them so I do want it to be in good if not perfect alignment. My usual process involves aligning dropouts and rd hanger. This was the first frame I have found that was out of alignment like this enough that I thought it needed to be corrected.

I will check other frame geometry as well as I can before proceeding.
The history - I"m quite sure the bike (or its rider) has been hit from the side by a car. I picked up a frame where it was obvious something like an SUV had hit it. (Trashed fork.) Got it home and realized the triangle was pushed a couple of cm to the side. (Dropout spacing and alignment is preserved because they were locked together by the hub locknuts and QR.)
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Old 01-23-21, 06:12 PM
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Originally Posted by gugie View Post
Sheldon Brown has a method (doesn't he always)? You can get it reasonably straight and rideable that way.

Better yet is to clamp the bare frame in a beefy vise and do the work like that with the string method.

Better yet is to use a
Park Frame Alignment Gauge, which will be more accurate than a string. I was able to salvage a fairly bent Zeus frame like this.

Best is to take it to a framebuilder with an alignment table if you want to get it dead on.

Your Le Champion is a 531 frame, which are pretty tough and can usually be bent back into shape with no discernable strength loss. Seeing your list of bikes, I'm guessing you'll want to take the time and perhaps $$ to get it as straight as possible?
Winner, winner, chicken dinner. I wouldn't try doing this unless I was experimenting on a frame that I don't really care about. If I was interested in keeping or selling it, I'd call the pros from Dover, get out of the way and let them do their thing. As Dirty Harry said in, I think, "Magnum Force": "A man's got to know his limitations."
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Old 01-23-21, 06:32 PM
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Originally Posted by bikingshearer View Post
Winner, winner, chicken dinner. I wouldn't try doing this unless I was experimenting on a frame that I don't really care about. If I was interested in keeping or selling it, I'd call the pros from Dover, get out of the way and let them do their thing. As Dirty Harry said in, I think, "Magnum Force": "A man's got to know his limitations."
For some people, a Motobecane Le Champion might be the nicest frame they'll ever own. Looking at the OP's list, this one's bottom of the barrel, and he's looking to flip it. This one might be the time to experiment instead of paying someone.

If the OP were driving distance from me, I'd just set aside an hour on a weekend and have him come by and show him how to do it with my tools for a six pack. Met some nice C&Ver's that way, which is more valuable to me than some nominal repair charge.
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Old 01-23-21, 07:02 PM
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I wouldn't know how to find the "thread" but over on CR, there was a discussion about bending frames back to where they should be. I expected the participants -- known vintage guys with really nice bikes-- to immediately advise to seek out a surface plate and a BB post. But most offered procedures involving brute force. Some 2x4s, but other methods involving getting on the floor with legs wrapped here or there and pulling and/or pushing...

it it might have been within the last few months.
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Old 01-23-21, 08:01 PM
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Hey thanks for all the help. Clamped the BB in a vice and just went to work with my hands. Got it within a mm or two with no big problems. I live in the boonies so no frame builders that close to me (well at least a couple hours drive) and I am pretty handy and had no problems trying this myself.
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Old 01-23-21, 09:28 PM
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Originally Posted by BlueDevil63 View Post
Hey thanks for all the help. Clamped the BB in a vice and just went to work with my hands. Got it within a mm or two with no big problems. I live in the boonies so no frame builders that close to me (well at least a couple hours drive) and I am pretty handy and had no problems trying this myself.
Excellent! Sometimes all you need is some confidence, and a splash of audacity to do something you've never tried before.
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Old 01-23-21, 11:12 PM
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Originally Posted by BlueDevil63 View Post
Hey thanks for all the help. Clamped the BB in a vice and just went to work with my hands. Got it within a mm or two with no big problems. I live in the boonies so no frame builders that close to me (well at least a couple hours drive) and I am pretty handy and had no problems trying this myself.
...great ! Remember to check (and re-align if needed) the dropouts so they are parallel.

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Old 01-25-21, 10:28 AM
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Originally Posted by randyjawa View Post
Tools needed to center stays - six foot long 2 x 4 lumber, Fishing line or really fine string. Measuring tape.

Once you have decided which way to bend the stays, do so but be careful at brazed or soldered joints. I always put something to add strength to the chain stay brace area near the bottom bracket.

Attach the string to the non-drive side of the rear drop (use a fender eye, for example). Run the string up to and around the front of the head tube. Tie the running end of the string (temporary knot) to the drive side drop fender eyelet. Make sure the string is tight with no sag...



Measure the distance from the non-drive side of the seat tube to the string - be as accurate as you can be. Repeat for the other side and compare. Using the piece of lumber, as pictured, carefully bend one stay at a time in the direction it should go. Check with the string again. The results will tell you that you need to bend more or bend back a bit (try to avoid the bend back issue to avoid work hardening the metal). Check the drop distance and adjust as required. Repeat until the seat tube to string measurement is equal on both sides. That should get you centered.

Next, make sure that your drops are 120 mm apart and then square them up to each other. That should get you where you want to go.
good visual, but use tex 90 thread, (heavy upholstery thread) much thinner, can be pulled taught, and more precise.
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Old 01-25-21, 10:41 AM
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when people say bend carefully, do it carefully, even if you have to try to bend and measure 5 times in a row with no result that is better than overbending
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Old 01-25-21, 11:18 AM
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when people say bend carefully, do it carefully, even if you have to try to bend and measure 5 times in a row with no result that is better than overbending
That is great advice! I 100% agree. Also, do not use my methods for aluminum frame sets!

good visual, but use tex 90 thread, (heavy upholstery thread) much thinner, can be pulled taught, and more precise.
I agree and apologize for not mentioning that. In practice, I use fishing line (used what was on hand) but it does not photograph well, hence the cotton mock up.
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Old 01-25-21, 11:58 AM
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-----

BlueDevil63 -

good to read that you now have things well sorted

the experience will make it an easier & faster procedure if it should come up again in your cycle work

one thing we have all forgot to mention is that the drive side set of stays can usually be moved laterally with less force than the non-drive side due to the double dimpling of the drive side chain stay


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