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Old 05-24-17, 01:18 PM   #1
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Repair options for a cracked rear dropout

I'm curious what you folks think could be done with this. Replace entire dropout? Repair? Hang on wall and admire?

Only pic I have, wondering if it's worth going after.
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Old 05-24-17, 02:06 PM   #2
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Maybe dropout replacement by a good frame builder would be most cost effective and safer
Not sure how much damage the removal and rebrazing heat might do to the chrome on the stays though....m
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Old 05-24-17, 02:15 PM   #3
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I have a hunch a good welder might be able to fix that. That is, weld the dropout while keeping the rest of the frame cold, so cold that the chrome isn't hurt. You'll have to do a lot of filing, then paint...
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Old 05-24-17, 02:20 PM   #4
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Just about anything's repairable. I'm wondering why a vertical dropout needs an adjustment screw? I would think you could just fill it will brass and do a little filing. A whole lotta flux on the chrome wold probably save it - some "paint to match" masking the chrome and dropout faces, and it might be as good as new, 'cept the screw hole would be filled.
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Old 05-24-17, 02:22 PM   #5
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had the same issue on my holdsworth but i was going to repaint the frame anyway. My holdsworth was not nearly as nice as yours but i wanted to save it. I believe yours is worth saving.
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Old 05-24-17, 02:33 PM   #6
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Another approach. Not as elegant but would not require heat. Sister on another piece of steel from the outside, cut to the dropout side profile and machined for the axle nut flats and adjusting screw rise. Three machine screws to hold it in place, one each beyond each stay and one into the hanger. Paint it the same red, use a longer rear wheel axle and QR and ride. One outfit that could certainly do this would be TiCycles. It wouldn't be cheap. (Beware, if you go this approach, they may suggest something better! They're pretty sharp.)

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Old 05-24-17, 02:33 PM   #7
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Take it to a professional welder and have him attempt a repair(weld, don't braze). You will loose the chrome on the drop and need to repaint it, but that is a small price to pay. I would also not go with the adjustment hole, weld it solid.

Needless to say, the repair will diminish the value of the frame but at least you will have it on the road. Will it break? Who knows but my bet would be that it will be as strong or stronger than it was, with the threaded hole.

If all that does not work, replace the drop and paint it up
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Old 05-24-17, 03:12 PM   #8
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Vertical dropout adjuster......did not really make sense, I gues, unless the builder was using jigs that were not aligned properly......
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Old 05-24-17, 03:20 PM   #9
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This frameset being a Cinelli, sure makes it worth fixing to "as original" condition.
I sure would not was what looks like a bodged up repair on it if it were mine.....
Unfortunately it's the chromed stays that will make the job difficult. Would have been a slam dunk to braze on a new dropout (can builders still find those dropouts?) If the stays were painted, as repaint of the stays would be so easy.
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Old 05-24-17, 03:27 PM   #10
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+1 on welding...Chamfer both pieces on all sides so you have V (valley) for a good strong weld. You can then later file the excess from the drop and still have enough strength in the weld that it will not cause any additional worry.
Bring it to a pro to do the welding. Use a heat sink at the tubes to minimize heat to chrome and paint and you will be good to go....no gas (Oxy-ace) welding, let electricity and wire be your friend. Easy and quick job.
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Old 05-24-17, 03:29 PM   #11
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Are they semi-vertical dropouts?
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Old 05-24-17, 03:34 PM   #12
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I have a welder I could trust, I'm more of a TIG solution for this one, remove paint within 3/8", talk to the welder, ditch the adjuster for this side, might require a tight V to obtain a clean surface, weld, and file back as needed.

Caswell plating after and touch up paint.

The TIG will add heat fast and of short duration.

otherwise, a stainless washer (maybe machined to fit) could be silver soldiered to the outside and cut back, extra material of some benefit to add strength.
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Old 05-24-17, 03:43 PM   #13
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Has anyone tried JB Weld in a situation like this ?
I know its a longshot - just tossing it out there as a clean no heat possiblility - especially if you filled the threads
The threads would provide teeth and gotta believe that would provide enough strength since the surrounding area still provides support as well ?

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Old 05-24-17, 03:50 PM   #14
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I have a welder I could trust, I'm more of a TIG solution for this one, remove paint within 3/8", talk to the welder, ditch the adjuster for this side, might require a tight V to obtain a clean surface, weld, and file back as needed....
The TIG will add heat fast and of short duration....
I concur 100%. TIG from a good welder, a small tight V so penetration could be achieved without resorting to brute-force massive amounts of heat for a long duration.

I believe it may be possible to avoid ruining the chrome as well. The key would be to fab some good aluminum or steel heat sinks that could be clamped tightly at the chromed area. That lets the heat from the welding escape outward rather than remaining localized. (Wet rags is not a good idea to keep the chrome cool IMO). Chrome itself can resist a fair amount of heat, think of guns that have chrome plated internal parts, or chrome piston rings.

The main thing though is to weld quick and fast, while doing a good job of course. Like soldering transistors: get in, get out fast.

Now if this required keeping the adjusting screws, then all bets are off, I would not trust a repair then.
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Old 05-24-17, 03:51 PM   #15
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Has anyone tried JB Weld in a situation like this ?
I know its a longshot - just tossing it out there as a clean no heat possiblility - especially if you filled the threads
The threads would provide teeth and gotta believe that would provide enough strength since the surrounding area still provides support as well ?
Not a chance in the world for JB Weld to work here. This is stressed in tension and the tensile strength/adhesion of JB Weld is nowhere near as good as the original steel.
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Old 05-24-17, 03:54 PM   #16
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Not a chance in the world for JB Weld to work here. This is stressed in tension and the tensile strength/adhesion of JB Weld is nowhere near as good as the original steel.
I definitely would defer to someone that was sure it wouldn't work.
It is never my first choice but figured this particular situation was worth a mention since you could fill the threads
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Old 05-24-17, 04:05 PM   #17
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Are they semi-vertical dropouts?
They look like Gipiemme 1800AX:

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Old 05-24-17, 04:12 PM   #18
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They look like Gipiemme 1800AX:

Not exactly the same. The ones on the bike, seems to have round flanges cast on to the dropout ends that go into the stay tubes......
Didn't Trek use similar rear dropouts on their bikes?
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Old 05-24-17, 04:16 PM   #19
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Is that a current production $2000+ frame?

There may be benefits of doing the job right. Contact Cinelli to see if you can acquire the dropout, then get it brazed in. Then chromed as needed. The paintwork pattern would lend itself to being touched up and would be invisible.

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Old 05-24-17, 04:29 PM   #20
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They look like Gipiemme 1800AX:

John, I was going to post and ask you, what's your opinion on TIG'ing vs filling the adjuster hole with brass, or even silver, and getting it to flow through the crack via capillary action, then file and sand?

I'm pretty convinced it could be done without ruining the chrome up on the stays, and since the dropouts are painted, that could be easily touched up.
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Old 05-24-17, 04:32 PM   #21
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I'm curious what you folks think could be done with this. Replace entire dropout? Repair? Hang on wall and admire?

Only pic I have, wondering if it's worth going after.
Couldn't find it on eBay, but it's clearly a Cinelli Supercorsa, well worth saving. Local seller?
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Old 05-24-17, 04:46 PM   #22
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Not a chance in the world for JB Weld to work here. This is stressed in tension and the tensile strength/adhesion of JB Weld is nowhere near as good as the original steel.
To follow up and give some real numbers here: the original steel forging, if it's a decent quality, should have a tensile strength well over 30,000 psi. Bear in mind that it failed.

JB Weld has an advertised tensile strength of 3960 psi. That's roughly 1/10 of the original steel--and that's under perfect conditions (optimum epoxy mixture, good surface prep, etc)

A TIG rod or MIG wire will be E70 or higher. That means it will have a tensile stress of 70,000 psi--much higher than the original steel. A properly executed weld is stronger than the original steel (granted, the weld must be executed properly, which is not always easy). Shucks, even if someone were to use a "tombstone" buzz-box arc welder with a 6011 "farmer's rod", that weld will be 60,000 psi which will still be stronger than any mild steel out there.
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Old 05-24-17, 05:06 PM   #23
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Not a chance in the world for JB Weld to work here. This is stressed in tension and the tensile strength/adhesion of JB Weld is nowhere near as good as the original steel.
Is it? I was trying to visualize the forces on the frame here. When you're pedaling, the axle would be pulled against the top of the dropout, which isn't compromised. The crack looks to me like it would have been caused by the derailleur being pulled inward, which is a risk going forward but wouldn't happen under normal operation. The quick release should push equally on both sides of the crack, but I suppose under heavy pedaling the flex in the frame could produce a lot of twisting force here, and maybe that (and not my first guess about the derailleur hanger) caused the failure. Then again, it seems to me like the flex from pedaling should be in the opposite direction, compressing the cracked area rather than pulling it apart.

Am I missing something? I'll admit a fair amount of ignorance, and I'm pursuing the question mostly for my own education. I actually would have thought it's possible to ride this as is.
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Old 05-24-17, 05:20 PM   #24
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I wrote that it was in tension, but of course it's not in tension 100% of the time--the "tension" represents the worst-case scenario which is what it must be designed for. In certain conditions, the reaction from the axle will indeed be pushing towards the front of the dropout or perhaps to the top/front (let's say the 1 o'clock position if the top of the drop was 12:00) . However, the worst-case scenario might be when the frame is flexed, perhaps leaning in a corner, or braking, and in those cases the axle is wanting to "open" the dropout slot. Perhaps hitting a pothole, then the axle is driving upwards into the rounded upper part of the dropout slot. That is also trying to "open" the dropout and thus putting the cracked area in tension. Or hitting a pothole while leaning and braking! A hundred pounds of force, twisting the other end of the axle, can act like a lever and try to force that slot open with tremendous force.
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Old 05-24-17, 05:21 PM   #25
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Is it? I was trying to visualize the forces on the frame here. When you're pedaling, the axle would be pulled against the top of the dropout, which isn't compromised. The crack looks to me like it would have been caused by the derailleur being pulled inward, which is a risk going forward but wouldn't happen under normal operation. The quick release should push equally on both sides of the crack, but I suppose under heavy pedaling the flex in the frame could produce a lot of twisting force here, and maybe that (and not my first guess about the derailleur hanger) caused the failure. Then again, it seems to me like the flex from pedaling should be in the opposite direction, compressing the cracked area rather than pulling it apart.

Am I missing something? I'll admit a fair amount of ignorance, and I'm pursuing the question mostly for my own education. I actually would have thought it's possible to ride this as is.
I was hesitant to post my outside the box idea because while my thoughts were along the same lines as yours, shared forces and back pressure relief due to filled threads, there may be other forces that more knowledgeable people can speak of. Since the next step may be a snapped dropout leading to a crash, I'll gladly defer to err on the side of caution.
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