Hey all,
I recently bought a second hand USE Alien seatpost off a gent on here, and it was fine when I got it. It was a 25mm with a shim to 27.2 but its always been a bit tight fitting into 27.2 seat tubes. Anyway, I transferred it to another bike but when I went to pull the post out to tighten the saddle rails properly, the bond between the carbon and the head failed and I ended up pulling just the head off!
I paid £40 for it and I would like to still use it if I can fix it. Is there anything I could use to bond it back together? I also thought of drilling a small hole through the carbon and through the insert of the head to bolt them together, but is it a good idea drilling through carbon? I have nothing to lose if I do it and it dosent go to plan but if its going to dramatically weaken the post to the post of snapping mid ride, then I dont know if Id do it!
Doug
"I have nothing to lose if I do it"
gonads already gone then?
talk to use they may be able to look at it/reglue it for you.
they almost certainly won't recommend banging a nail through it to hold it in place.
haha, I mean I have nothing financially to lose. The post is useless as it is, and I would never dream of selling it on after I had 'fixed' it with a bolt or sticking it back together. Obviously I wouldnt do it if its just going to snap on me, but I thought I'd ask anyway!
I just thought as the Superstar carbon posts have tilt adjustment through a big rod that goes through the metal outer sleeve and inner carbon post in theory it would be a similar idea as long as drilling it didnt wreck the carbon.
Hmm, difficult. If it were metal, the I'd suggest using Araldite Rapid Steel, and drilling a small hole either side, to pop-rivet it (done it with a frame, has held up fine). But it's carbon. Standard Araldite and use pop-rivets to try and prevent sudden detachment of the head, should the glue fail. Maybe even standard Superglue, but I'm no engineer.
Send back to USE?
Personally, I'd just glue and rivet the bastard. What's the worst that can happen?
DO NOT drill carbon composite - you'll break the fibres giving it its strength - it's not like metal. Almost certainly possible to rebond it using something like araldite, but it's all about the surface prep before you start - definitely speak to USE, they're generally very helpful.
araldite 2015 may be the ticket
I'd glue it back together with stabilit express. Sticks stuff together like nothing else and smells great!
I thought stuff like seatposts were made using loads of little bits of carbon fibre, soaked in resin then squashed together in a mould and baked? Rather than using woven sheets?
Therefore, would drilling not be too much of an issue? IE; you can carefully cut the ends off carbon bars, which are made the same way, so I don't understand how drilling the bastard would be an issue? Woon't delaminate, surely?
Or would drilling break the seal, as it were, and the stuff could crumble away from the edges?
The idea of rivetting would be to prevent sudden failure, more than to hold it, as the glue would hopefully be doing that job.
Thomthumb, just looked that up and that could be a good solution. I did think it would be a good idea to go over the head with a bit of 600 wet and dry before hand.
The epoxy is pretty expensive, probably best just to bin it.
Araldite, FFS...
Y
Honestly though, speaking as someone who builds with carbon fibre, send it back or bin it, if the head came off the tube is likely ovalled or the bonding area contaminated, and only USE will know for sure.
Araldite, FFS...
I had a Bontrager carbon post come to bits on me. One of the really early ones - I think it was made in conjunction with Titec.
Anyhow. Cleaned it up, and remembering a tip from a lecturer at uni, stuck it back together with the slow-setting araldite.
Left it leaning on a radiator for about a week to cure nicely.
Good to go. Worked for 8yrs until I sold it.
Drilling/riveting would be pretty pointless as if it's moved enough to need that for integrity, it'll be in bits in no time.
Rivets are usually only used in this sort of assembly to hold it still whilst the glue is drying, and as it's a part that doesn't matter if rotationally it's off cock, then I'd not fret.
YMMV
I did the same with my Ti Sumo (alrhough it merely came loose). USE fixed it on a 3 day turn round and it's been fine since.
Give them a call. The worst they can do is say no.
+1 on the sending it back. Write a good cover note and explain your predicament and I'm sure they'll try and help. You may even get a new post.
Um......
If you've ended up with a pretty stiff post with no top, could you either bodge or buy something along the lines of a Ritchey Stubby seat clamp affair like they have on Scott Addicts or Scott Scales?
I thought stuff like seatposts were made using loads of little bits of carbon fibre, soaked in resin then squashed together in a mould and baked?
You thought wrong. Cutting the ends of carbon bars is totally different - it doesn't matter cutting the fibres there, as you no longer need any strength between the bars and the bits you cut off. You very definitely do need strength between both sides of where you'd be drilling for a rivet.
Ok. Fair enough. I spose it could compromise the structural integrity of the carbon tube. I was just pondering a 'belt and braces' approach, like I did with my frame.
What's wrong with Araldite? There's different types for different applications.
I'd bung some Araldite on it. Or would a chemical bond be needed? something that melts the carbon resin stuff a bit, and then sets hard?
[img] http://images.fotopic.net/?iid=ymvqv2&outx=480&quality=70 [/img]
Not pretty, but it's held good for 2 1/2 years so far, and shows no sign of failing. The bloke who done the rivetting said he thought the Araldite would be sufficient on it's own.
I will contact USE but its been cut down annoyingly, meaning that alone might make them say no to offering any help. The Araldite seems a good idea. At the end of the day, if it fails again I wont fix it again, but it might work and after having spent £40 on it 2 weeks ago, Im reluctant to throw it away in order to spend more money on another post. If it fails again it just means the saddle will swivel in the carbon tube, no major biggy. The head is still a tight fit in the carbon, hopefully meaning its not ovalised.
Cheers for the help guys!