Is this a goner?
Steel. Building it up for my girlfriend, and I've only just noticed it
Tell a lie it's not magnetic. Bum
frame is defo pumped.
Although I'd err on the side of caution, is that definitely knackered given that the crack is above all the welds? Other than the issue of keeping the seatpost at the correct height, what would happen if you just used a super-long seatpost that went into the frame well below the junction of the top tube, seat tube and seat stays? Incidentally, how long is that seat post?
The seatpost is tiny, I only bought it today. 19cm I think, from the advert
The bloke I bought the frame from had a massive seatpost in it, most of it poking out the top.
Wish I'd have checked it properly, but after leaving home at 5am with two 6 year olds and three hours of their jabbering in the car I was pretty near the end of my tether
Yeah I mean it's annoying because the frame would still otherwise function perfectly well but holding a seatpost in it for the long term may be an issue.
You could just do it up and see how it goes. A failure is unlikely to be catastrophic because the saddle would just slip down
Could you just get the seat height correct and weld or epoxy the post in place?
It wouldn't be pretty, but I'd be tempted to repair it with carbon. Take the paint off around the seat tube/top tube junction, file the welds smooth, and then lay up plenty of UD carbon tape and epoxy, using vinyl tape with pinpricks in it as a compression layer. I think I'd try to get the tape going over the top tube, round the seat tube, then under the top tube in a sort of figure of 8 shape. Then sand the carbon smooth.
It's a bit of a bodge, and I'm sure the purists will be choking on their Richard Sachs branded mocchachino, but it'd work.
Don’t you have to have a layer of something separating carbon and aluminium so you don’t get some sort of chemical corrosion?
Ideally, yes. If you were doing it 'properly' you put down a layer of glass fibre tape down first. But that's really only where the bond is structural, say with alloy lugs and carbon tubes. This would be more of a carbon sarcophagus to hold the alloy bits in place.
I suppose you could always just leave the paint on and make it structural!
Could you epoxy in a long seatpost shim as a sleeve? The lip on its top would hold the broken seat tube down. If you wanted to get technical you could put a length of threaded rod down to the BB shell and use that to hold the whole thing in compression while it cures. It wouldn't be as solid as a long seat post down past that joint, but it would retain its ability to clamp the seat post properly, albeit with a smaller seat post size.
It takes a 25.2mm seatpost, so not sure if that would work?
It's not the end of the world, the frame cost £55 and a drive to Lincoln and back, but I've got a Rick Powell tandem.
I was hoping to use this on the turbo trainer and move the seatpost, but could just swap bikes instead of raising the saddle.
It's a bit annoying because I've been collecting bits for this bike for 6 months or so, but that's life I suppose
With a longer seatpost you could bodge a new clamping mechanism like this:
A 2piece clamp (from an old front derailleur?) and you could get rid of the broken off top.
It is off to my friend tomorrow to see if he can fix it.
Otherwise it'll be off here https://www.abfineart.com/welding---chasing to see what they can do.
It may not end up being pretty, it probably wouldn't go on the ABfineart portfolio
post-weld updates plz
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