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Both front and back slots on a carbon CX frame :(. Looks like it's due to a 30.9 post being run in a frame that is 31.6! I've fitted a looong 31.6->27.2 metal shim and a 27.2 post for now but am undecided about what to do long term.
Front outer
Front inner
rear inner (not convinced this is a crack)
rear outer (could just be paint this side)
What make of frame?
I would say crack on. Pun intended.
As long as you have plenty of seat post insertion it'll be fine.
I had a steel Decade Virtue made from super thin tange prestige that has a crack in the same place and its been there years. I couldn't sell it obviously but gave to it a mate and he still rides it absolutely fine. I was up Holmbury Hill last night with him.
What make of frame?
Boardman so nothing super special or high value but it is nice and light. Not been used much and everything else on it is spot on.
A carbon fibre repair kit would sort that out but I’d stick to one slot. They are exceptionally large and two of them? Use a good quality clamp afterwards like a BBB Strangler or a Madison Elite. This is of course after contacting Boardman, just in case!!
Carbon can be fixed much more effectively than a metal tube eh?
I'd just keep an eye on it and keep riding if it doesn't get any bigger though
A carbon fibre repair kit
As luck would have it my local carbon 'expert' 😀 is turning a Porsche into something else and has offcuts!
For a repair I'd be thinking sand back, drill end of crack then build a reinforcing ring around the whole post but below where it is sized for the clamp. Then blend in and paint. I will contact Boardman to confirm the post size but this is a 2016 model frame that was NOS in 2022.
Or is it something else into a Porsche??
I would drill the ends of the cracks and just keep an eye on them. If you've sleeved it down to 27.2 mm, that should spread the stress away from that area.
Yep I'd be happy enough running that after drilling the ends to stop it propagating further and just doing a quick epoxy repair.
Any particular epoxy?
Can you fit a bigger cleat clamp like one that’s twice as deep. Maybe drill a small hole at the bottom of the crack to stop it cracking further (like on plastic kayaks that have cracked)? I reckon as long as you’ve got enough post inserted you should be ok.
This is all assuming you are out of warranty
Any particular epoxy?
Araldite is very good- boat/aircraft industry
Possibly think about a seatpost shim epoxied in.
This is all assuming you are out of warranty
Well out yes and as it had the wrong sized post in I don't think that would apply anyway.
Can you fit a bigger cleat clamp like one that’s twice as deep.
Don't think so easily. As with many carbon frames the seat clamp sits on a bit that is recessed. I'd have to extend that which I think would be difficult to do accurately without a cutter. Will look into it though.
Araldite is very good-
Cool, thanks.
A random thought is to go find a dentist on a fancy bike.
Joking aside, when I go to the dentist I sometimes get a quick X ray on a couple of repaired teeth. The xray film would fit easily inside a seat tube and is a little bit flexible and would be a quick, cheap way to say if a 'crack' is a crack
Looks like it's due to a 30.9 post being run in a frame that is 31.6
How on earth did it not slip?
Any particular epoxy?
We use this a lot at work (Motorsport/Automotive composites) as it has a nice quick cure time and you don't have to buy a large amount. You may need to buy the dispensing gun though if you don't have one available/to borrow.:
https://www.easycomposites.co.uk/permabond-ET5428-black-epoxy-adhesive
How on earth did it not slip?
No idea, I'm going to talk to the previous owner when I get a chance. The 30.9 was tight to move though due I think to the surface corrosion it (post is dead).
Thanks jfab. Black as well which is a bonus.
How on earth did it not slip?
By being overtightened until it deformed and then cracked.