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Snap there goes the old Trek

Old 08-08-19, 12:41 PM
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Chris Chicago
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Snap there goes the old Trek

this happened yesterday. from what I gather it maybe can be tig welded. but could be cheaper to just find another frame. It's an early 80s trek 610, 24in.

I had squeezed a 130mm hubbed wheel in last year without cold setting or realigning dropouts, might have something to do with it.

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Old 08-08-19, 12:59 PM
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Originally Posted by Chris Chicago View Post
...I had squeezed a 130mm hubbed wheel in last year without cold setting or realigning dropouts, might have something to do with it.

...not to mention the frame's entire previous history of usage, possibly ridden with a bent freewheel axle, etc.
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Old 08-08-19, 01:00 PM
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No fun; the 600 series are nice bikes.
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Old 08-08-19, 01:07 PM
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I assume this happened while you were riding. Out of curiosity, what was the effect? Sudden pop? Immediately noticeable? We’re you able to ride home? Did you notice any signs (micro-cracks, paint chips) in the area beforehand?
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Old 08-08-19, 01:08 PM
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New dropout and you’re good to roll...
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Old 08-08-19, 01:19 PM
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Originally Posted by gaucho777 View Post
I assume this happened while you were riding. Out of curiosity, what was the effect? Sudden pop? Immediately noticeable? We’re you able to ride home? Did you notice any signs (micro-cracks, paint chips) in the area beforehand?
yeah, pop or snap sound then wheel starts rubbing the chainstay. I tried getting it on straight for 10minutes before noticing the crack. that would be fun to have on video, me scratching my head and swearing. was not able to ride it.

didnt notice anything prior but didnt look at it too closely.
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Old 08-08-19, 01:25 PM
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it was nice but had some small dents and a replacement fork. I'm weighing that against fixing it.

coincidentally I had the same bike with better version of the frame in my possession this spring but decided to flip it rather than swap frames
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Old 08-08-19, 01:46 PM
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It's a relatively easy repair to braze in a new dropout, therefore probably pretty cheap repair, as long as a repaint isn't factored in.

It happened occasionally. Freewheel hub axles can flex a small amount since the bearings are inboard. This allows the drive side dropout to fatigue. Sometimes they'd break at the chainstay right in front of the dropout.

Forcing a 130 without realigning dropouts etc did not help.
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Old 08-08-19, 05:01 PM
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That is a fairly easy repair, but then it's also not all that difficult to find 80's Trek 600 series bikes. In my area they show up in Craig's list quite frequently for around $300. If the bike had other issues, then I would just look for a new one rather than try to repair it.

As for forcing a 130 mm hub in without cold setting... For what it's worth, I've ridden tens of thousands of miles on old Treks with 130mm hubs and I've never had a problem like that.

Steve
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Old 08-08-19, 05:45 PM
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I have replaced drop outs several times. Easy repair, but matching the drop out to the other one will be difficult and will require someone willing to work a drop out to get as close as possible to the one good one. Could have both replaced at the same time so they match, but I don't think it is necessary to match.
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Old 08-08-19, 06:44 PM
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Curious to know, what brand/'model dropout is that?
Some dropouts like the Suntour GS seem to have more of their share of cracking at that exact place, through the years.....
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Old 08-08-19, 07:23 PM
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It's pretty certain that happened due to dropout misalignment. When I took my frame in to have it painted a couple of years ago, the frame builder doing the painting pointed out that my dropout was cracked in just such a way that dropout misalignment was the cause (even though mine was only a 120 -> 126 spread and I had the frame cold set and supposedly aligned by an experienced mechanic). He noted that clamping the quick releases shut on misaligned dropouts puts a constant stress on the dropout that results in the cracks and that he'd seen this on many bikes where people had just spread the frame without realigning the dropouts. Fortunately mine wasn't too bad and he managed to braze it back together.
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Old 08-08-19, 09:22 PM
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Grind a slight V in the crack and TIG.
Cold set it way it was supposed to be.
Touch up the minimally invasive TIG repair.
Ride.

-Kurt
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Old 08-09-19, 05:33 AM
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Broken Suntour Dropout

Originally Posted by Chombi1 View Post
Curious to know, what brand/'model dropout is that?
Some dropouts like the Suntour GS seem to have more of their share of cracking at that exact place, through the years.....
Back in the 70's we sold some Crescent's bikes. The mid range non Campy Pepitas came with Suntour dropouts instead of Campy's. We had a number of the drive side Suntour dropouts break. We though that they were made of a steel that got hard from cooling too fast and ended up being brittle???

They were a different model dropout than the OP's but maybe the same cause/issue???

Originally Posted by davester View Post
It's pretty certain that happened due to dropout misalignment. When I took my frame in to have it painted a couple of years ago, the frame builder doing the painting pointed out that my dropout was cracked in just such a way that dropout misalignment was the cause (even though mine was only a 120 -> 126 spread and I had the frame cold set and supposedly aligned by an experienced mechanic). He noted that clamping the quick releases shut on misaligned dropouts puts a constant stress on the dropout that results in the cracks and that he'd seen this on many bikes where people had just spread the frame without realigning the dropouts. Fortunately mine wasn't too bad and he managed to braze it back together.


This not to scale drawing show that spreading a 120mm rear triangle to 126mm without realigning the dropout leaves them sitting with a 5° toe in (assuming they they were properly aligned to begin with). Going from 120mm to 130mm leaves the dropout even more misaligned.



Not only does the misalignment put stress in the dropouts but causes the axle to bend enough when the QR is clamped down to result in uneven wear on the cones. They will be angled in at the same amount as the dropouts. This causes uneven wear in the cups too and can lead to bent or broken rear axles.




It's not just frames that have been spread, I've seen a lot of brand new high end bikes and frames with misaligned dropouts.

I bought this pair of Campy Dropout Alignment Tools in 1975 and I've used them on most bikes that I've worked on. One of my best bike tool investments.


Here's a YouTube video from RJ the Bike Guy that shows how to make a set of DIY dropout gauges with some cheap hardware.



Originally Posted by cudak888 View Post
Grind a slight V in the crack and TIG.
Cold set it way it was supposed to be.
Touch up the minimally invasive TIG repair.
Ride.
-Kurt


Over a 2 week period a few years back I ran into a brand new stem with a crack, a crank arm with a crack and when I checked out what looked like a scratch in the paint, a cracked dropout.

I stripped paint off the "scratched" area and sure enough...

I had a frame builder friend TIG weld it for me. The dropout broke when he ground the V notches in so it was ready to go. It was a Shimano UF dropout which had a reputation for cracking in that area.





He ran a TIG bead on the inside and outside of the broken area, shot it with some primer and voilà. The weld will be stronger than the dropout.

TIG welding is a lot easier and results in much less stress in the stays than replacing the whole dropout.

verktyg

Last edited by verktyg; 08-09-19 at 05:54 AM.
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Old 08-09-19, 01:40 PM
  #15  
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I just verified some numbers and, not meant to be an insult to whomever produced that dropout drawing, but dude, get your facts straight!

Using a 415mm chainstay length (as spec'd, so c-c BB to dropout) and subtracting for the bottom bracket shell, you have a hypotenuse of roughly 390mm for your triangle. Nudge that chainstay 3mm (120 -> 126) or 2mm (126 ->130) and the angular deflection is 0.44 degrees and 0.29 degrees respectively. While cold setting may be nice for quickly slipping a wheel in and out, to say that not cold setting is going to cause long term harm to the frame is a bit misleading. Old dropouts crack regardless of spreading and I'm guessing most people cold setting frames aren't going to bother trying to adjust out a <0.5 degree angle on the dropout. They likely don't even have the proper tools to measure that angle. Perhaps at 120 -> 130mm you could start seeing some issues but that's a pretty rare thing.

And even if I felt like the angle was an issue, it still wouldn't stop me from spreading the stays on old aluminum Cannondales, because otherwise you couldn't do any updating with those frames
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Old 08-09-19, 02:27 PM
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Originally Posted by verktyg View Post
Back in the 70's we sold some Crescent's bikes. The mid range non Campy Pepitas came with Suntour dropouts instead of Campy's. We had a number of the drive side Suntour dropouts break. We though that they were made of a steel that got hard from cooling too fast and ended up being brittle???

They were a different model dropout than the OP's but maybe the same cause/issue???





This not to scale drawing show that spreading a 120mm rear triangle to 126mm without realigning the dropout leaves them sitting with a 5° toe in (assuming they they were properly aligned to begin with). Going from 120mm to 130mm leaves the dropout even more misaligned.



Not only does the misalignment put stress in the dropouts but causes the axle to bend enough when the QR is clamped down to result in uneven wear on the cones. They will be angled in at the same amount as the dropouts. This causes uneven wear in the cups too and can lead to bent or broken rear axles.




It's not just frames that have been spread, I've seen a lot of brand new high end bikes and frames with misaligned dropouts.

I bought this pair of Campy Dropout Alignment Tools in 1975 and I've used them on most bikes that I've worked on. One of my best bike tool investments.


Here's a YouTube video from RJ the Bike Guy that shows how to make a set of DIY dropout gauges with some cheap hardware.

https://www.youtube.com/watch?v=PsU8IkkFaok






Over a 2 week period a few years back I ran into a brand new stem with a crack, a crank arm with a crack and when I checked out what looked like a scratch in the paint, a cracked dropout.

I stripped paint off the "scratched" area and sure enough...

I had a frame builder friend TIG weld it for me. The dropout broke when he ground the V notches in so it was ready to go. It was a Shimano UF dropout which had a reputation for cracking in that area.





He ran a TIG bead on the inside and outside of the broken area, shot it with some primer and voilà. The weld will be stronger than the dropout.

TIG welding is a lot easier and results in much less stress in the stays than replacing the whole dropout.

verktyg
I think you may have an error in your dropout toe in angle value. Using a 120mm to 126mm change of spacing means a change of 3mm per side. So, a triangle with a height of 3mm and a base of 430mm (the amount of angular change when increasing the rear spacing by 3mm per side) would be 0.2 degrees (per side). I used an angle calculator online.
So I'm saying, if the dropouts were aligned to begin with at 120mm, spreading to 126mm, would result in a 0.2 degree misalignment.
Please check me, but I think I'm right.

Last edited by Hobbiano; 08-09-19 at 02:31 PM.
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Old 08-09-19, 03:24 PM
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Originally Posted by Hobbiano View Post
I think you may have an error in your dropout toe in angle value. Using a 120mm to 126mm change of spacing means a change of 3mm per side. So, a triangle with a height of 3mm and a base of 430mm (the amount of angular change when increasing the rear spacing by 3mm per side) would be 0.2 degrees (per side). I used an angle calculator online.
So I'm saying, if the dropouts were aligned to begin with at 120mm, spreading to 126mm, would result in a 0.2 degree misalignment.
Please check me, but I think I'm right.
I agree that the 5 degrees is incorrect, but I believe that the 0.2 is also incorrect. Calculating arcsine of 3/430 gives an angle of 0.4 degrees. No matter, the important point is that not aligning the dropouts, even by this small number of degrees, will result in broken axles, ruined bearings and/or cracked dropouts.
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Old 08-09-19, 03:55 PM
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I stripped paint off the "scratched" area and sure enough...

I had a frame builder friend TIG weld it for me. The dropout broke when he ground the V notches in so it was ready to go. It was a Shimano UF dropout which had a reputation for cracking in that area.





He ran a TIG bead on the inside and outside of the broken area, shot it with some primer and voilà. The weld will be stronger than the dropout.

TIG welding is a lot easier and results in much less stress in the stays than replacing the whole dropout.

verktyg [/QUOTE]

Nice clean work, you were lucky that the rear drop did not have to be removed from the stay...saves the paint for the most part so that only minor touch-up is required!
Best, Ben
Ben
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Old 08-09-19, 04:12 PM
  #19  
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I paid $100 for a local frame builder to replace a Campy dropout on a Pinarello, which also got touched up on a Marchetti frame alignment table. The paint/chrome loss from the heat is the biggest issue for some bikes.
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Old 08-09-19, 04:46 PM
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Argue with my CAD program...

Originally Posted by joejack951 View Post
I just verified some numbers and, not meant to be an insult to whomever produced that dropout drawing, but dude, get your facts straight!
Originally Posted by Hobbiano View Post
I think you may have an error in your dropout toe in angle value.
Originally Posted by davester View Post
I agree that the 5 degrees is incorrect, but I believe that the 0.2 is also incorrect.
I knew the number crunchers were going to jump on this... Hey guys, argue with my CAD program.

Quick and dirty way to find out, put a frame on a layout table and after checking the dropout alignment, spread the rear triangle and then measure the angles with a dial or digital protractor. To throw gas on the fire, over half of the top name frames that I worked on since the 1970's had misaligned dropouts, whether new or used.

Earlier this year I picked up a 1980's De Rosa frame. I check the head tube and BB faces on almost every frame I've worked on. I didn't have a BB facing tool for 36mm Italian BBs so I took the frame to Ed Litton. We/he had to remove over .5mm on each side to get the BB faces parallel and perpendicular! So much for the work of the master (Hugo)!!!

I retired back in January after 40 years as a manufacturing engineer/tool designer/cutting tool engineer. Now I don't even think about stuff like number crunching.

CAVEAT: I did the drawing in about 5 minutes late one night for a post where I was trying to show why dropouts need to be realigned after spreading the rear triangle. So my numbers are off a little but the basic concept remains the same.

verktyg

Last edited by verktyg; 08-09-19 at 05:56 PM.
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Old 08-09-19, 04:46 PM
  #21  
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Originally Posted by davester View Post
I agree that the 5 degrees is incorrect, but I believe that the 0.2 is also incorrect. Calculating arcsine of 3/430 gives an angle of 0.4 degrees. No matter, the important point is that not aligning the dropouts, even by this small number of degrees, will result in broken axles, ruined bearings and/or cracked dropouts.
I would estimate it's closer to 1 degree per size per side since there's extra stiffness at the BB due to bigger tube sections and the chainstay bridge. The stays would bend as beams with most of the bending near the dropouts due to the taper.
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Old 08-09-19, 05:34 PM
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Originally Posted by Kuromori View Post
I would estimate it's closer to 1 degree per size per side since there's extra stiffness at the BB due to bigger tube sections and the chainstay bridge. The stays would bend as beams with most of the bending near the dropouts due to the taper.
Just figured out how to set the angular dimension precision on my free shareware cad program. 0.4 degrees it is. Theoretically. But it does sound reasonable that it is actually greater due to most of the flexing occurring where the stays are thinner.
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Old 08-09-19, 07:07 PM
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Originally Posted by cudak888 View Post
Grind a slight V in the crack and TIG.
Cold set it way it was supposed to be.
Touch up the minimally invasive TIG repair.
Ride.

-Kurt
On second thought, this is a better way to fix it. Few people know how to braze anymore, but TIG skill is pretty common. Plus there's no worry about the dropouts matching, and less touch up to do.
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Old 08-10-19, 03:57 AM
  #24  
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TIG quick fix for broken dropout

Originally Posted by Salamandrine View Post
On second thought, this is a better way to fix it. Few people know how to braze anymore, but TIG skill is pretty common. Plus there's no worry about the dropouts matching, and less touch up to do.


The first repair that I did on a frame was replacing standard Campy 1010 horizontal dropouts with Campy 1069 vertical dropouts. I had a frame built for me and it was a case of "OH NO! You did what I asked for!"

The chain stays were so short that I could hardly get a sewup wheel in and out, even deflated. I'd been through a commercial welding course plus I took 2 semesters of jewelry and metal crafts working with silver and gold as part of my industrial design studies so I knew what I was doing... or so I thought.

It's very easy to overheat the thin wall seat and chain stays when trying to remelt the brazing material enough to remove the dropouts. The remelt temperature is much higher than the original melting point for most brazing alloys.

I cut the dropouts apart so that it was easier to remove them in 2 pieces, one stay at at time. I cheated on the second side and ground out most of the dropout with a carbide burr.

I've done it myself and watched experienced frame builders have the heated areas of lugs, rear stays and fork blades crystallize and disintegrate as the steel gets up to the melting point of the brazing material. Just a few seconds...

"and less touch up to do."

Before touch up painting:



After, it passes the 5 foot test:



verktyg

Last edited by verktyg; 08-10-19 at 04:04 AM.
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