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Safety of repaired dropout

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Safety of repaired dropout

Old 11-03-21, 12:25 PM
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db143
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Safety of repaired dropout

Hi all, I've had a scan of this board for a suitable place for this and not seen one - please redirect me if I'm out of place.

I'm looking at buying a frame at the minute and the owner before the current one had it repaired at the drive side dropout. The current owner has sent picture of the repair and also has had the frame built up and ridden. There's no evidence of damage elsewhere on the frame to my eyes. Could you advise me on:

1. What could have caused this damage? It doesn't seem like a crash would be the culprit here.
2. Is it safe to ride this frame provided the weld was done competently?

General comments around damage and repair on this area of a frame are all welcome. Many thanks in advance for your expert advice!



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Old 11-03-21, 02:24 PM
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guy153
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I don't know what causes this but have seen (and repaired) it before. It's not hard to repair because that's a thick piece of plate. But this hasn't been done all that well. It looks from the first shot like the weld doesn't go all the way through. You need to cut a bevel and fill it with weld in order to make the join go across the whole thickness. It's also a bit ugly with too much build up (was probably MIG or flux core) that he hasn't ground down. But this is mainly an aesthetic problem.

It probably won't fail soon though and when it does it shouldn't be all that dangerous or dramatic.

It could easily be ground out and welded better because there's plenty of metal there.
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Old 11-03-21, 02:35 PM
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Thanks for the reply. From what you are saying, if it's a good quality frame at a good price, it wouldn't be a write off because of this? Would it be a simple re-fix job for a framebuilder?
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Old 11-03-21, 03:39 PM
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Yes the repair should be quite easy for any competent welder, doesn't need to be a specialist framebuilder. And because of where it is it doesn't matter if it's repainted less than perfectly.
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Old 11-03-21, 04:37 PM
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Those socketed dropouts would make for an easy replacement if you are able to find the drop out.
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Old 11-03-21, 07:50 PM
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Fairly easy to replace those dropouts except for the chrome. Welder probably died.
I have seen those dropouts, but I'm not sure you can buy ones with the same dimensions.

Looks like it's a Longshen LR1 or LR10. Ceeway carries them. Nova used to carry them, but I don't see any now.
Ceeway link: go down to "articulated angle"
https://www.framebuilding.com/NEWPAR...20Dropouts.htm

Last edited by unterhausen; 11-03-21 at 07:57 PM.
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Old 11-03-21, 08:00 PM
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It looks to me that it was not repaired properly. The crack should have been v cut to create a wider area for the weld creating a stronger repair. It will probably break again running cassette rear hub will decrease the chance of breaking sooner than running a freewheel type hub.
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Old 11-04-21, 06:11 AM
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Thanks all for your replies. The frame is great value but I'll have to balance that with cost of having this looked at. Really appreciate the responses.
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Old 11-04-21, 06:20 AM
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Since the dropout is essentially cracked in half already, you need to have that fixed. I'm not sure I would feel comfortable just getting it welded again. I could replace the dropout, but the frame would have to be nearly free before I would be interested in buying it. For me, $20, for someone else, $50 max. And that's a maybe. In the U.S. that costs up to $200 to replace the dropout. Not sure about U.K. builders. You could get a local welder to weld it again from the other side for considerably less, but I think I would limit how far away from a train station that I rode it.
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Old 11-04-21, 10:44 AM
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Originally Posted by unterhausen View Post
Since the dropout is essentially cracked in half already, you need to have that fixed. I'm not sure I would feel comfortable just getting it welded again.
it should be fine to weld it again as it's 5 or 6mm thick. But rather than weld it from the other side I'd grind the whole weld out, bevel it properly, and fill it in again. The existing weld looks a bit untidy so may also be porous and not well fused.

Replacing the dropout would be more expensive I agree. You'd need a specialist framebuilder, a replacement part, and to remove and redo more paint.

Whereabouts in the UK is the OP?
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Old 11-04-21, 02:39 PM
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Originally Posted by pwyg View Post
It looks to me that it was not repaired properly. The crack should have been v cut to create a wider area for the weld creating a stronger repair. It will probably break again running cassette rear hub will decrease the chance of breaking sooner than running a freewheel type hub.
Not V cut but ground a notch in.

Not for a wider area but for full penetration.
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Old 11-04-21, 03:35 PM
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Originally Posted by SkinGriz View Post
Not V cut but ground a notch in.

Not for a wider area but for full penetration.
No, V grooved to increase the weld contact area for strength. This is a common practice in welding steel. Notching it will not necessarily allow more penetration. Not as good of penetration as a V groove will allow. Grooving it allows significantly more surface area for the weld material to attach too. Do a little research on Tig welding if you think i am wrong.
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Old 11-04-21, 04:04 PM
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Was that welded or brazed?

I think I would choose the V-grove and tig welding. ... see below.

However, if it was brazed, then the filler should penetrate into the crack reasonably well. I can't say about the strength of a butt brazed joint.

Originally Posted by guy153 View Post
it should be fine to weld it again as it's 5 or 6mm thick.
It may be 5 or 6mm at the bolt surface, but that dropout has been significantly thinned, so it may be 2 or 3mm at the weld/joint. It may well not need a deep grove for welding,and one may get adequate penetration using welding on both sides and a minimal grove.

If one is brazing, another option would be to cut a plate to fit into the slot and braze it in place, significantly increasing the surface area of the repair.
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Old 11-05-21, 01:31 AM
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Originally Posted by pwyg View Post
No, V grooved to increase the weld contact area for strength. This is a common practice in welding steel. Notching it will not necessarily allow more penetration. Not as good of penetration as a V groove will allow. Grooving it allows significantly more surface area for the weld material to attach too. Do a little research on Tig welding if you think i am wrong.
I know what a V groove is. I just wouldn’t refer to it as cutting.
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Old 11-05-21, 07:13 AM
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Originally Posted by guy153 View Post
Whereabouts in the UK is the OP?
I am in London so there are some good frame builders around who will be more than capable of this.

The frame is made with Columbus Genius tubing and is going for £230 - adding the cost of the replacement/repair would take it to around 400. This is what I'm weighing up, I have to say I am tempted, but equally would be simpler to wait out for an alternative.

Please feel free to continue specialist frame building conversation as I have got what I asked for
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Old 11-05-21, 09:54 AM
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I'm not sure if anyone really answered the subject line. Having the word "safety" makes me look at this with the rider's safety in mind. Rear drop out cracks are common enough to have a pretty well known record of being a shame, a hassle, while can sometimes result in a sudden skidding stop more often as shifting or tire rub issues, but rarely has a fall down or rider injury result. (Significantly different then a front drop out fracture).

The down and dirty option is to grind off the chrome where brazing will be done, cut a triangular gusset to fit against the drop out's crotch and the chain/seat stays and braze that in place.

Just the same I would suggest moving on to a frame with no cracks. There's a lot of fish in the sea. Andy
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Old 11-07-21, 08:01 PM
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One thing that I'd add to Andrew's comment is that steel often fails slowly. So if you watch the repaired area for cracks, chipping paint, etc, then it might be possible to predict a failure.

It might depend a bit on one's riding. Distances, alternative transportation, how you'll get home, etc. RACING? Group Rides?

At times an imminent failure is an incidental finding. At other times a full failure happens at the most inopportune moment.

Looking at the previous repair I have troubles discerning exactly how it was done. Was some kind of body filler used? That could make it more difficult to visualize the repair, as well as monitor for damage progression.

You can think of that dropout as essentially channel iron with 2 flanges and webbing between. Much of the strength of the channel is at the flanges.

From the second photo it looks like the person doing the repair ground into the flanges somewhat, but didn't fully fill his grind. That may indicate that there was a "V" cut under all the welds or brazing areas.

The actual weld may be strong enough, although I would have expected continuing welding across all parts of the flanges where one would have a significant amount of strength, as well as resistance to flex.

So, you have 3 options.
1) ride as-is. Perhaps strip the repair to inspect more carefully.
2) Verify metal used. Strengthen repair by adding a gusset in the slot, and making sure the flanges are properly filled/strengthened.
3) Replace one or both rear dropouts. Likely the most expensive option, but one ends up with "good as new".

£230 sounds high, but perhaps the seller would negotiate.
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