Seat Tube crack: safe to ride?
07-10-18, 10:31 AM
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Seat Tube crack: safe to ride?
I have a question for a someone who understands the physics of steel frames better than I do.
I own a vintage (1969) lightweight (for the time) thin tubed, lugged steel frame. I was told it’s Reynolds 531 but I am not sure I believe it. The frame was repainted in the 1980s in an incorrect colour/decal scheme and it’s generally worthless. It is, however, incredibly stylish and the combination of no value and high style makes it perfect for locking up around nyc. I used it for a couple of years as “beater” with various internal gear hub set ups.
When I stored the frame I noticed that there is a crack in the seat tube which extends from the “pre cut” section of the seat post lug (where the seat post binder goes) vertically for about one inch, if my memory serves me well. The seatpost (which is stuck in, and is probably what caused this in the first place) extends well below the cut, of course.
i would like to get the frame out of storage and use it again as a town bike. But now that I have noticed this, I can’t help but wondering whether it is safe, or whether the seat tube could give up on me suddenly, maybe while I am riding in front of a bus. I am light-ish (70kg/156lbs) and this would be a fairly upright 5 speed town bike, not one that I would take on loaded tours or anything.
Repairing it properly is not an option because I can’t throw flames at it in a nyc apartment, and since it’s worhtless (it only has affective and aesthetic value) I don’t want to spend money to bring it to a framebuilder, who any way would refuse to touch such a lowly frame.
So the question really is just, safe to ride or not? Or do you need pictures to assess? (The frame is in storage right now, so I was hoping to get an answer in theory before I go and pull it out in practice). I attach a photo of its last incarnation because why not - but you cannot see the crack in it.
Thanks in advance for any help and suggestions!
I own a vintage (1969) lightweight (for the time) thin tubed, lugged steel frame. I was told it’s Reynolds 531 but I am not sure I believe it. The frame was repainted in the 1980s in an incorrect colour/decal scheme and it’s generally worthless. It is, however, incredibly stylish and the combination of no value and high style makes it perfect for locking up around nyc. I used it for a couple of years as “beater” with various internal gear hub set ups.
When I stored the frame I noticed that there is a crack in the seat tube which extends from the “pre cut” section of the seat post lug (where the seat post binder goes) vertically for about one inch, if my memory serves me well. The seatpost (which is stuck in, and is probably what caused this in the first place) extends well below the cut, of course.
i would like to get the frame out of storage and use it again as a town bike. But now that I have noticed this, I can’t help but wondering whether it is safe, or whether the seat tube could give up on me suddenly, maybe while I am riding in front of a bus. I am light-ish (70kg/156lbs) and this would be a fairly upright 5 speed town bike, not one that I would take on loaded tours or anything.
Repairing it properly is not an option because I can’t throw flames at it in a nyc apartment, and since it’s worhtless (it only has affective and aesthetic value) I don’t want to spend money to bring it to a framebuilder, who any way would refuse to touch such a lowly frame.
So the question really is just, safe to ride or not? Or do you need pictures to assess? (The frame is in storage right now, so I was hoping to get an answer in theory before I go and pull it out in practice). I attach a photo of its last incarnation because why not - but you cannot see the crack in it.
Thanks in advance for any help and suggestions!
Last edited by Va1984; 07-10-18 at 11:03 AM. Reason: typos
07-10-18, 04:11 PM
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It has a bent fork too. Possibly a bent top tube and down tube. So it's a dead loss with no possibility of economic repair.
I hate to make a judgement sight unseen, but it sure sounds like the seatpost crack isn't a safety issue.
I hate to make a judgement sight unseen, but it sure sounds like the seatpost crack isn't a safety issue.
07-10-18, 06:56 PM
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What makes you say the fork is bent? It tracks well and everything seemed straight to me.
Last edited by Va1984; 07-10-18 at 07:08 PM.
07-10-18, 07:33 PM
#4
Bad example
07-10-18, 07:37 PM
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Thank you - this is quite interesting, if you’re right. Do you think the drum brake arm could have caused it? I knew when I used it with drum brakes that I was risking it... but then, not noticing any changes on a day to day basis, I just rode it like that for a year or so. I’m adding other pics, in case they help resolve the fork question — since the seat tube crack seems less important in comparison.
07-10-18, 08:29 PM
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It's my opinion that the stuck seat post is the first issue that needs to be resolved. All else would wait till the post is out. Andy
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AndrewRStewart
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07-11-18, 08:40 AM
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fork looks bent to me and the tell is that the clearance between the fender and the downtube is very small. That isn't normal. A direct head-on collision will bend the fork evenly. It's really hard to tell from the pictures, but I would look at the bottom of the down tube and top tube for signs of buckling. People commonly say that the fork will save the frame from damage, but with lightweight tubing that's not always true. And the headtube angle looks really steep.
That damage wouldn't keep me from riding the bike, but it would definitely keep me from repairing it.
That damage wouldn't keep me from riding the bike, but it would definitely keep me from repairing it.
07-22-18, 02:55 PM
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Forks can be bent evenly so the tracking alignment isn't effected. The stability might be as the trail will be different. Usually a hub brake will load one fork blade more then the other and so any braking induced bending is focused on one blade. getting both blades to evenly bend with a single sided load is not likely.
It's my opinion that the stuck seat post is the first issue that needs to be resolved. All else would wait till the post is out. Andy
It's my opinion that the stuck seat post is the first issue that needs to be resolved. All else would wait till the post is out. Andy
fork looks bent to me and the tell is that the clearance between the fender and the downtube is very small. That isn't normal. A direct head-on collision will bend the fork evenly. It's really hard to tell from the pictures, but I would look at the bottom of the down tube and top tube for signs of buckling. People commonly say that the fork will save the frame from damage, but with lightweight tubing that's not always true. And the headtube angle looks really steep.
That damage wouldn't keep me from riding the bike, but it would definitely keep me from repairing it.
That damage wouldn't keep me from riding the bike, but it would definitely keep me from repairing it.
...but at least I don’t see any problems on the downtube or top tube, nor any dreaded ripples:
... all in all this is just a 100% worthless frame that I am attached to. So as long as it’s safe to ride around as a local beater, I would like to.
07-22-18, 03:17 PM
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Attach a seat, and see if it can be lubed and wiggled out.
Once you have the seatpost out, stop drill the crack, then put as long of a seatpost as you can find back in.
You'll also verify that the old post had adequate insertion.
With a good long seatpost, and stop drilling the crack, the seat issues should be fine. Just check it every once in a while. You'll have plenty of warning before failure, as long as you look at it, and even a total failure is unlikely to cause much more than an inconvenience. You'd have to completely sheer at least 2 tubes.
The fork damage is up to you. Do the bearings turn ok?
07-22-18, 10:02 PM
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If the seatpost is in the right place, put a binder bolt in it and ride it. You might think about a different fork
07-23-18, 06:11 PM
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Thanks for the better photos. I now question my first thought about a bent fork. In these new shots the fork looks pretty straight WRT the head tube.
As to the crack- It's a lot less then I was thinking. Actually not too uncommon as that point of the frame sees a few differing stresses. The clamping action of the lug/binder is a constant distortion. The difference in wall thickness between the tube (likely about .6mm) and the lug+tube (maybe about 2mm) is a lot so the thinner tube is where the weak point is. When the frame is brazed it's easy to over heat the thin wall while the thick portion isn't up to temp yet. And they stop the binder slot right at that point of stress, the lug's lower edge.
If this were my frame I would first get that post out. Then I would extend the binder slot another 10mm (or so) below the lug and end it in a hole (upside down key hole). The frame and fork would get a full alignment, get chased and faced then be Frame Saved inside. Andy
As to the crack- It's a lot less then I was thinking. Actually not too uncommon as that point of the frame sees a few differing stresses. The clamping action of the lug/binder is a constant distortion. The difference in wall thickness between the tube (likely about .6mm) and the lug+tube (maybe about 2mm) is a lot so the thinner tube is where the weak point is. When the frame is brazed it's easy to over heat the thin wall while the thick portion isn't up to temp yet. And they stop the binder slot right at that point of stress, the lug's lower edge.
If this were my frame I would first get that post out. Then I would extend the binder slot another 10mm (or so) below the lug and end it in a hole (upside down key hole). The frame and fork would get a full alignment, get chased and faced then be Frame Saved inside. Andy
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AndrewRStewart
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07-30-18, 06:21 PM
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fork looks crashed to me too. i'd keep riding it or bend it back 10mm or so.
the rear crack can be tig welded in about 5 minutes.
the rear crack can be tig welded in about 5 minutes.
07-30-18, 07:23 PM
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I have heard from multiple welders that tig in the presence of brazing filler is a no-go
07-30-18, 08:18 PM
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well its either that or nothing/keep the crack. tig is low heat method
07-30-18, 08:22 PM
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the point is that the brazing filler will contaminate the weld and there will be a bigger damaged area.
08-21-18, 04:55 PM
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Interesting thread.
This may be stupidly obvious (if so, my bad): If working with the frame upside down (seat lug lower than the defect), could one TIG weld without risk of contamination by brazing filler?
Also, if the heat spread to the lug I'd guess minimal brazing material would run out and gravity would likely keep it out of the repair area. Cheers!
This may be stupidly obvious (if so, my bad): If working with the frame upside down (seat lug lower than the defect), could one TIG weld without risk of contamination by brazing filler?
Also, if the heat spread to the lug I'd guess minimal brazing material would run out and gravity would likely keep it out of the repair area. Cheers!
08-22-18, 05:20 AM
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filler goes towards heat, it will definitely go uphill.
I still don't see what is driving that crack, so I would leave it alone. Make sure the seat post is the right size and longer than it needs to be and just watch. I think someone caused the crack by aggressively prying the seat lug ears apart. Seems to me that I can see marks in the shape of a screwdriver there.
I still don't see what is driving that crack, so I would leave it alone. Make sure the seat post is the right size and longer than it needs to be and just watch. I think someone caused the crack by aggressively prying the seat lug ears apart. Seems to me that I can see marks in the shape of a screwdriver there.
08-22-18, 06:58 AM
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The RH binder ear looks to have collapsed in, I suspect like many production frames using pressed lugs the ears are hollow if not filled during construction. So this lug has a few issues at the same time IMO. The crack, the compromised ears are the two I see. If the lug has been closed up from a too small a post we can't really tell from mere photos but that would be #3 .
As to why there's a crack see my post #11 . Andy
As to why there's a crack see my post #11 . Andy
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08-22-18, 09:52 AM
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My statement was not about why there is a crack, rather addressing if it will grow. I think it's more of a tear than a crack and there is no driving force that will make it grow from where it is now. I could be wrong. I have seen lug ears in better condition, but I have also seen lug ears that worked that were in much worse condition. As a bike to ride around town, I wouldn't mess with it. Just keep an eye on that crack.
