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I've inherited a frame my father used to ride and was planning on getting it blasted and coated.

Checking it over it all seems to be in fair condition (its decent 531 Reynold tube), some rust, but not deep. Except the tube behind the bottom bracket shell between the chain stays (what do you call that bit?) which has a large rust hole.

rust hole

How bad is this? Safe to ride? Fixable?

If it didn't have sentimental value I'd probably chuck it, but it does so I'd like to use it if possible.

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    The tube is there to support the kickstand, and likely was damaged by a loose kickstand and/or overtightening of the kickstand. It provides very little additional strength/stiffness to the chain stays. The worrisome point is whether the rust has gotten into one of the chain stays -- probably not, but it would take careful inspection to be sure. – Daniel R Hicks Feb 24 '19 at 18:39
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    The tube is there to support the kickstand, and likely was damaged by a loose kickstand and/or overtightening of the kickstand. And that means it's likely one of the thickest chunks of steel on the bike. And it's completely rusted through. The worrisome point is whether the rust has gotten into one of the chain stays -- probably not, but it would take careful inspection to be sure. The problem is you can't see inside. And there are ways for water to get inside places you can't see. Chain stays can have vents. Downtubes have shifter bosses where screws might penetrate. – Andrew Henle Feb 24 '19 at 19:01
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    @AndrewHenle - In my experience that tube is quite often very thin. Encountering one that's been crushed is not at all unusual. And, yes, water gets into the frame through several channels, most notably the seat tube. I've seen numerous bikes with the bottom bracket rusted up, even with no visible external rust. – Daniel R Hicks Feb 24 '19 at 20:18
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    @AndrewHenle - The most effective check for rust damage would be to open up the bottom bracket and check inside. If any significant amount of water has gotten inside it will be immediately obvious. – Daniel R Hicks Feb 24 '19 at 23:56
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    Do you have access to a bore scope camera? They're reasonably cheap on various chinese websites, and use a phone as a display. Consider feeding one in through the bottom bracket area and up both chainstays. You're looking for rust, or worse sunlight coming through a pinhole. – Criggie Feb 25 '19 at 6:47
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When building frames high quality tubing, such as Reynolds 531 is often only used on the main tubes (i.e., main triangle) and if you are lucky the rear triangle. Less critical tubes, such as the cross-brace, will typically use a lower quality steel, such as a mild steel, which is more susceptible to rusting and will show earlier signs of deterioration. Therefore, there is still a chance that while the cross-brace has severely deteriorated, the main structural frame may have remained relatively intact.

There is of course no way to know for certain until you strip off all the components and paint and really have a close inspection of the main structural tubes. Once the paint is off you can can see how deep the surface rust goes. You can also try tapping the tubes lightly with a small hammer to see if you hear tone changes (i.e., severe thinning due to interior rusting). Careful inspect the chain and seat stays as some frame builders use cheaper steel here, which may not have faired as well. Finally, the cross-brace was often used for fender mounting and was usually drilled, paint damage at this point is also common which could have further accelerated the rusting.

Even if you do all this and the main frame seems reasonable intact, I would still be cautious in use as there is no way to determine with absolute certainty the safety of the frame without pressure testing it (i.e., ridding it). This is a delicate proposition as you want to ride it as lightly as possible until you see how it reacts and slowly build more confidence as you use it in differing situations. One of the things working in your favor is the failure mode of steel is a lot better than other frame materials such as aluminum and especially carbon, which you should generally avoid riding if you have concerns over structural damage.

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How bad is this?

Bad. Real bad.

Safe to ride?

No. I sure wouldn't.

Fixable?

No, not in my opinion. That's what you can see. What does the inside of the seat tube look like? Or the insides of the welds that hold the steer tube to the top and down tube?

Just look at the peeling paint on the bottom bracket. And water doesn't generally pool nor collect and remain on the outside of the bike...

If it has significant sentimental value, blast it, clean it thoroughly, and then see what you find. It might be salvageable, but I wouldn't wager too much on that possibility. That cross brace is completely rusted through.

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    Downvote with no comment? Seriously? On a steel frame that has one of what's likely one of the thickest chunks of steel completely rusted through? – Andrew Henle Feb 24 '19 at 19:03
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    I didn't downvote, but I guess that downvote might have to do with the harshness of your words. You see, while I would generally agree that this rusted connection is a really bad thing, I wouldn't immediately jump to the conclusion that the frame is unrecoverable: This connection had its paint damaged quite early, and was likely continuously covered in wet dirt afterwards. That this part has rusted away does not mean that the rest of the frame is in similar condition. The really bad thing is that water might have entered the chain-stays through that hole. That's what needs to be checked. – cmaster - reinstate monica Feb 24 '19 at 19:18
  • @cmaster Still think it was my wording that got me the downvote? Your answer got one too. ;-) – Andrew Henle Feb 24 '19 at 23:52
  • Well, sometimes I just don't get why people downvote... – cmaster - reinstate monica Feb 25 '19 at 7:56
  • In this user's case it's usually the combination of rudeness, incorrectness and revenge downvotes. Note that I didn't downvote because while this is exaggerated, it is not completely wrong. – ojs Feb 25 '19 at 16:13
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I would say that the frame is probably not safe as it is. For one, I don't know how important that connection was for the structure of the frame. But most importantly:

Water is likely to have entered the chain-stays through the hole created by the rusted connection. The consequence is, that you cannot trust the chain-stays without checking them. And chain-stays are a vital part to the security of your bike. So, you don't want to take this lightly.

Depending on how far the water (and rust) entered the frame you can have either of these outcomes:

  • No hole in the chain-stays => the frame can be salvaged by replacing the connection.

  • Hole in the chain-stays and water/rust entered them => you may need to replace the chain-stays.

  • Hole in the chain-stays and water/rust also entered the bottom bracket from that direction => well, looks like you need to replace the bottom bracket as well. I guess this kind of repair could get expensive due to all the welding that would need to be done.

I guess, it should become clear which of these it is once you have fully removed the rotten chain-stay connection. Look at the state of the chain-stays themselves at the point where the connection was welded on, and proceed accordingly.

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  • Having to replace whole tubes raises a Ship Of Theseus question/dilemma. At which point do you have to replace so many parts that you might as well replace the whole bike (or at least frame)? – Michael Feb 24 '19 at 20:10
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    @Michael Of course. But the OP explicitly stated: "If it didn't have sentimental value I'd probably chuck it, but it does so I'd like to use it if possible." So, I guess, it's important for him to know just how much he'll need to replace, and then decide for himself whether it's really worth it for him. – cmaster - reinstate monica Feb 24 '19 at 21:14
  • You could still restore it to static Museum condition with period parts, which then would be a shame if you can't ride it, considering the price for such bits. Or just restore the frame for decorative purposes. – Carel Feb 26 '19 at 20:39

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