130mm for a 126mm hub frame
#76
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How did you set and align them? What tolerance are you able to hold? If such is not a trade secret, please share.
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No, you didn't even understand what I was talking about -- which isn't real impressive.
Fine, let's pretend I'm off by 300%. Now it is 3 thin human hairs. Or 3 layers of paint. Does that change the point at all? No, it does not.
I understand how the tool works. Unlike you, I also understand that it does nothing to square those faces with the frame. 'Square to the frame' is different from simply being parallel to each other. That's precisely why I asked about finding the centerline plane of reference -- and no one has proposed a method for that operation that results in the necessary precision.
Sure, check away, if it makes you happy. Hork on them with crude tools too, if you like. But if you think you are improving the situation by eyeballing it, and bending things with crude tools, you probably have another think coming.
Fine, let's pretend I'm off by 300%. Now it is 3 thin human hairs. Or 3 layers of paint. Does that change the point at all? No, it does not.
I understand how the tool works. Unlike you, I also understand that it does nothing to square those faces with the frame. 'Square to the frame' is different from simply being parallel to each other. That's precisely why I asked about finding the centerline plane of reference -- and no one has proposed a method for that operation that results in the necessary precision.
Sure, check away, if it makes you happy. Hork on them with crude tools too, if you like. But if you think you are improving the situation by eyeballing it, and bending things with crude tools, you probably have another think coming.
The point of squaring the dropouts is to serve the hub. Centering is a function of other parts of frame geometry. No one needs super accurate frame alignment, nor has anyone suggested this is necessary.
The point you keep ignoring, I will restate for you: Bending 425mm stays with the crude methods that we use does not result in a .25 degree change in the dropout from parallel. The actual number is unknown, variable, and usually great enough to benefit from dropout alignment. Which you'd realize if you had done this enough.
I agree with your strawman argument, though: One hair of misalignment is unimportant. Everyone agrees with that. No one is arguing with you about that. So you can stop bringing that up as if you are having an argument about that. You aren't.
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I was not attempting to bring you into anything against your will. You said 'Unless I'm missing something', so I replied with what that might be.
0.25 degrees is the previously-mentioned thin human hair, or layer of paint, and I think that's asking a lot with "decent" tools -- although that word will have different meanings to different people.
For the most part, I agree with your previous post and wasn't arguing with you. I just think the tolerance on "truly square" in this application is larger than most here seem to.
0.25 degrees is the previously-mentioned thin human hair, or layer of paint, and I think that's asking a lot with "decent" tools -- although that word will have different meanings to different people.
For the most part, I agree with your previous post and wasn't arguing with you. I just think the tolerance on "truly square" in this application is larger than most here seem to.
As for the acceptable tolerance, I explained my reasoning working from what Campagnolo said in their tech info back in the sixties, and the tool they provided for the job. So, IMO half a degree is probably fine and 1/4 22nddegree about the limit of what's achievable.
Also keep in mind that changes in hub design, probably make the entire system more forgiving than was the case 50 years ago.
FWIW, I consider most of this argument based on a 4mm change in width pointless. IMO, if you have the tools, skill, and desire, you might as well do the job. But, no big deal if you lack any of the 3.
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Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#79
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And much of the point is exactly that people are not thinking about what they are doing in this instance.
The point you keep ignoring, I will restate for you: Bending 425mm stays with the crude methods that we use does not result in a .25 degree change in the dropout from parallel. The actual number is unknown, variable, and usually great enough to benefit from dropout alignment. Which you'd realize if you had done this enough.
I note with amusement that you completely ignored that remark.
So how many hairs are required before it does become important?
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You haven't the slightest idea about my experience, and you are the one who apparently eyeballs frames and believes that you are accomplishing a precise adjustment -- so you've revealed quite some about yours.
And much of the point is exactly that people are not thinking about what they are doing in this instance.
Then learn the correct terminology. If you are just making the dropouts parallel, without concern for their location, then you are not squaring the frame.
I did not ignore this point -- I specifically said that if it makes you happy, you can pretend that that calculation is off by 300%, and triple that value, but the point does not change.
I note with amusement that you completely ignored that remark.
So how many hairs are required before it does become important?
And much of the point is exactly that people are not thinking about what they are doing in this instance.
Then learn the correct terminology. If you are just making the dropouts parallel, without concern for their location, then you are not squaring the frame.
I did not ignore this point -- I specifically said that if it makes you happy, you can pretend that that calculation is off by 300%, and triple that value, but the point does not change.
I note with amusement that you completely ignored that remark.
So how many hairs are required before it does become important?
Quote where I said "squaring the frame". I said "squaring the dropouts", which refers to making them both parallel and directly across from each other - like the sides of a square, but not like the sides of a rhombus. Read.
Where did I say I "eyeball" frames? There's an alignment tool for dropout centering, and a separate tool for the dropouts themselves. But I guess you wouldn't know that, because of your inexperience?
Again, you have no idea how far the dropouts are off, because - instead of checking - you have a theory about how the stays bend. And your theory is simplistic and wrong. Because the dropouts are at the end of two stays each, and the chain and seat stays are very different in stiffness, the dropouts can end up slightly twisted and otherwise off far more than 300% of .25 degrees. And that's assuming that neither dropout was tweaked by the act of spreading itself, depending on the tool used.
You don't know what happens to the dropouts during spreading, because you haven't checked. You assume you know because you have a simplistic theory about what is happening. And you don't see the downsides to having dropouts well out of square - not just two hairs.
#81
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Ironically, way back up top, before you started getting all defensive and arguing nonsensical points for no reason, you agreed with me:
Which is fine, but let's not pretend that such offers real precision. And your first sentence in that quote isn't correct, either, at least with respect to the precision that we are discussing. Of which you would be aware, had you the experience you are now claiming to have.
Just for the record and all, I manufactured a couple (non-bicycle) parts for a friend two days ago, and my CNC rig held +/- .0012" on the critical dimensions ( roughly 1/5th of a hair ). In case you wanted to blather on some more about my experience, ya know.
And your theory is simplistic and wrong. Because the dropouts are at the end of two stays each, and the chain and seat stays are very different in stiffness, the dropouts can end up slightly twisted and otherwise off far more than 300% of .25 degrees. And that's assuming that neither dropout was tweaked by the act of spreading itself, depending on the tool used.
Last edited by TC1; 03-21-24 at 02:30 PM.
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I have owned a dropout alignment tool, but it didn't do the job that was required, so I gave it to a friend who is less meticulous. I now use other tools, and metrology instruments.
Ironically, way back up top, before you started getting all defensive and arguing nonsensical points for no reason, you agreed with me:
When I inquired as to how you assure that your dropouts are squared to the frame, you said:
When pressed for a description of how that comparison to the frame tubes takes place, you had no reply -- seemingly because your method is that which most people use, taking a step back, closing one eye, and havin' a look at it.
Which is fine, but let's not pretend that such offers real precision. And your first sentence in that quote isn't correct, either, at least with respect to the precision that we are discussing. Of which you would be aware, had you the experience you are now claiming to have.
When did I say that I do not check them? I am simply realistic about what can be accomplished by the crude hand tools and eyeball measurements being discussed here. I'm also aware, as I mentioned a page or so ago, that most dropouts are not even manufactured to sufficient tolerances to make the operations that you are claiming, possible to the precision you claim.
Just for the record and all, I manufactured a couple (non-bicycle) parts for a friend two days ago, and my CNC rig held +/- .0012" on the critical dimensions ( roughly 1/5th of a hair ). In case you wanted to blather on some more about my experience, ya know.
What tools are you using to spread frames that cause you to routinely fubar them so completely? A proper tool that will not mangle your frame costs less than $5 to make, with parts available at any hardware store. Are you using that half-assed 2x4 method? If so, no wonder you have such problems.
Ironically, way back up top, before you started getting all defensive and arguing nonsensical points for no reason, you agreed with me:
When I inquired as to how you assure that your dropouts are squared to the frame, you said:
When pressed for a description of how that comparison to the frame tubes takes place, you had no reply -- seemingly because your method is that which most people use, taking a step back, closing one eye, and havin' a look at it.
Which is fine, but let's not pretend that such offers real precision. And your first sentence in that quote isn't correct, either, at least with respect to the precision that we are discussing. Of which you would be aware, had you the experience you are now claiming to have.
When did I say that I do not check them? I am simply realistic about what can be accomplished by the crude hand tools and eyeball measurements being discussed here. I'm also aware, as I mentioned a page or so ago, that most dropouts are not even manufactured to sufficient tolerances to make the operations that you are claiming, possible to the precision you claim.
Just for the record and all, I manufactured a couple (non-bicycle) parts for a friend two days ago, and my CNC rig held +/- .0012" on the critical dimensions ( roughly 1/5th of a hair ). In case you wanted to blather on some more about my experience, ya know.
What tools are you using to spread frames that cause you to routinely fubar them so completely? A proper tool that will not mangle your frame costs less than $5 to make, with parts available at any hardware store. Are you using that half-assed 2x4 method? If so, no wonder you have such problems.
To spread I use my hands. But we are speaking about all the techniques, not just your favorite one. There's no reason to be overly precise with one part of the process if it is followed up with a more precise step.
Last edited by Kontact; 03-21-24 at 08:48 PM.
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We have to have our steam gauge certified. Afterwards we get a certificate of certification.
No joke.
No joke.
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Leave it to someone in a specialized field to grossly overcomplicate something simple and well understood. If you have a hammer, everything looks like a nail...
#88
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Also, you may want to consider the ramifications of my comment way above about the consistency of the thickness of cast dropouts. Specifically that such is insufficient to enable your ***-2 to measure what you are trying to use it to measure to the precision you are claiming. ( Edit: apparently this site does not allow mentioning the name of that particular Park Tool, so folks will have to use their imaginations. )
I can't really believe I just spent a dozen comments arguing about precision with someone who a) agreed with me initially, before deciding to have an argument about nothing and b) uses their hands to mangle a frame instead of simple, superior methods.
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No wonder your results are so poor. Scratch together $5 and make an appropriate tool that avoids winding up with a crookedly-bent rear triangle in the first place.
Also, you may want to consider the ramifications of my comment way above about the consistency of the thickness of cast dropouts. Specifically that such is insufficient to enable your ***-2 to measure what you are trying to use it to measure to the precision you are claiming. ( Edit: apparently this site does not allow mentioning the name of that particular Park Tool, so folks will have to use their imaginations. )
I can't really believe I just spent a dozen comments arguing about precision with someone who a) agreed with me initially, before deciding to have an argument about nothing and b) uses their hands to mangle a frame instead of simple, superior methods.
Also, you may want to consider the ramifications of my comment way above about the consistency of the thickness of cast dropouts. Specifically that such is insufficient to enable your ***-2 to measure what you are trying to use it to measure to the precision you are claiming. ( Edit: apparently this site does not allow mentioning the name of that particular Park Tool, so folks will have to use their imaginations. )
I can't really believe I just spent a dozen comments arguing about precision with someone who a) agreed with me initially, before deciding to have an argument about nothing and b) uses their hands to mangle a frame instead of simple, superior methods.
But, as I pointed out already, we aren't talking about what I do, but what everyone should do. Whether you use a jig, a lever, your hands, etc - you should check the dropouts with an alignment tool after you check the dropout centering (yes, the alignment tool or a taut string and calipers are sufficiently accurate), because you just applied a bunch of weird forces to complex metal shapes, and they don't always behave predictably.
So you make incremental changes to stays, stop when you are within a millimeter each side, then square the dropouts (which might not have started square in the first place). It takes less than five minutes with shop tools, maybe a few more with homemade dropout tools.
The important concepts in this discussion are Significant Digits and Tolerance Stacking. How close does each measure have to be, considering how a bicycle works; and how much does each alteration effect other measures? Steel bikes aren't made of rods, but tubes that don't just bend linearly but twist and interfere with each other. We cold set frames because of concern with putting the tubing under constant tension - but there is really no way to remove all of it because we can't measure how much the final position of the dropout is actually the result of opposing tensions between the seatstay and chainstay.
Given that complexity, you should check/correct your dropout alignment last, so your wheel goes in and out easily and your axle has a minimum of asymmetric forces acting on it. And if you see no point, why bother to cold set the frame at all? Like I said, if you do nothing at all it will be fine - Shimano originally planned for users to just cram the 130 wheel into the 126 frame.
As for you TC1, I don't think there is a single person on this thread that thinks whatever point you're making is sensible. You are simultaneously saying that all bike techniques are too crude measurement wise, yet insist that something you never measure is fine. Which is why no one agrees with you.
Last edited by Kontact; 03-22-24 at 08:51 PM.
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Is this shtick? How long do you two intend to keep thr act going?
If it's not an act, one might fairly infer that each of you considers the other to be an ignoramus, (or worse). If you keep it up much longer you'll convince folks that you're both right.
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FB
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#91
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I don't think TC1 is stupid, but I do think he has a forest for the trees problem.
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#92
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As for the other thread, I've been called worse, and am happy to let him stew in his own sauce.
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I think the guy in the other thread knows what's going on much better than the responses he's gotten.
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The common methods of spreading rear dropouts (or "fork ends," per Sheldon Brown's strongly expressed preference) were mentioned only once in this thread that I remember (those being the use of 2 x 4's, washers and nuts and a threaded rod. etc.).
Just dropping in to point out that, while the left and right dropouts often move equal distances from the frame's center line when a threaded rod is used, or when the mechanic just grabs and pulls the sides apart, equal movement is not guaranteed.
The advantage of the 2 x 4 method is that, if you begin with a frame whose alignment has been measured to be correct, you can bend one side at a time the correct distance. In the case of a 124-mm OLD being changed to 130 mm, that would be 3 mm per side, obviously.
Once you've moved each side 3 mm, all that's left to do is align the dropouts using the Campy H dropout tool or the Park equivalent and then reconfirm that the frame's alignment is still good.
Just dropping in to point out that, while the left and right dropouts often move equal distances from the frame's center line when a threaded rod is used, or when the mechanic just grabs and pulls the sides apart, equal movement is not guaranteed.
The advantage of the 2 x 4 method is that, if you begin with a frame whose alignment has been measured to be correct, you can bend one side at a time the correct distance. In the case of a 124-mm OLD being changed to 130 mm, that would be 3 mm per side, obviously.
Once you've moved each side 3 mm, all that's left to do is align the dropouts using the Campy H dropout tool or the Park equivalent and then reconfirm that the frame's alignment is still good.
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OK Kids, please stay on topic, and skip the "personal" remarks.
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We cold set frames because of concern with putting the tubing under constant tension - but there is really no way to remove all of it because we can't measure how much the final position of the dropout is actually the result of opposing tensions between the seatstay and chainstay.
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My 2x4 method is not your 2x4 method - I just put the two pieces inside the chainstays next to the dropouts and lever them against each other - if the ends are 6 inches above the stays and the pieces are 2 ft long I have 4x mechanical advantage. If the stays don't bend the same on each side I clamp the bottom bracket shell in the bench vise and push/pull them into alignment, but the 2x4 works well enough most of the time.
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My 2x4 method is not your 2x4 method - I just put the two pieces inside the chainstays next to the dropouts and lever them against each other - if the ends are 6 inches above the stays and the pieces are 2 ft long I have 4x mechanical advantage. If the stays don't bend the same on each side I clamp the bottom bracket shell in the bench vise and push/pull them into alignment, but the 2x4 works well enough most of the time.