? Cracked seat tube
Discussion
Hi guys,
I've just bought what I thought was a fantastic bike- a supposedly unused from new 2008 Bianchi 928 SL.
The bike looks fantastic, everything appears to be original including the tyres and wheels and on first inspection the condition seemed just as described. There's even still protective film on the Ultegra shifter hoods.
On asking how the bike had managed to go 15 years without being used I was advised by the seller (who seems a really nice guy) that he'd bought it 2-3 years back from a former bike shop owner. He told me that he hadn't used it personally and now in his 60s he doesn't think he's going to get around to it. He told me that the shop owner had become insolvent and had taken a handful of bikes before the rest of his stock was taken as the business went under. He'd apparently eventually decided that the time had come to clear his remaining bikes which was when the chap I bought it from came to own it.
Anyway, on getting the bike home I went to get it out of the back of the car and with the seat post facing me I was very disappointed to notice what looks like a small crack in the seat tube just below the seat post clamp. If this is a crack I presume it's from where the seat post could have been overtightened.
I know the answer is probably going to be that it's impossible to say from the pictures but I wondered if anyone had any thoughts on whether this looks like a crack, whether it looks like the sort of thing that's going to cause trouble when someone starts riding the bike or whether it could just be a factory finish defect.
I've sent the buyer a message to ask his permission to remove the seat post to allow a closer look and would welcome your thoughts.
I've just bought what I thought was a fantastic bike- a supposedly unused from new 2008 Bianchi 928 SL.
The bike looks fantastic, everything appears to be original including the tyres and wheels and on first inspection the condition seemed just as described. There's even still protective film on the Ultegra shifter hoods.
On asking how the bike had managed to go 15 years without being used I was advised by the seller (who seems a really nice guy) that he'd bought it 2-3 years back from a former bike shop owner. He told me that he hadn't used it personally and now in his 60s he doesn't think he's going to get around to it. He told me that the shop owner had become insolvent and had taken a handful of bikes before the rest of his stock was taken as the business went under. He'd apparently eventually decided that the time had come to clear his remaining bikes which was when the chap I bought it from came to own it.
Anyway, on getting the bike home I went to get it out of the back of the car and with the seat post facing me I was very disappointed to notice what looks like a small crack in the seat tube just below the seat post clamp. If this is a crack I presume it's from where the seat post could have been overtightened.
I know the answer is probably going to be that it's impossible to say from the pictures but I wondered if anyone had any thoughts on whether this looks like a crack, whether it looks like the sort of thing that's going to cause trouble when someone starts riding the bike or whether it could just be a factory finish defect.
I've sent the buyer a message to ask his permission to remove the seat post to allow a closer look and would welcome your thoughts.
That looks more like an imperfection in the lacquer rather than a crack to me but then it's really hard to tell from the pics (hard to take pics to show it I know).
I also can't see it being the kind of place you'd get a crack like that as it's designed and manufactured to have some flexibility. To crack it you'd have to be tightening up the seat collar with no post inserted surely?
Like addey said, get the post out and have a look from the inside, it'll be raw carbon so should show up pretty clearly if it's cracked.
I also can't see it being the kind of place you'd get a crack like that as it's designed and manufactured to have some flexibility. To crack it you'd have to be tightening up the seat collar with no post inserted surely?
Like addey said, get the post out and have a look from the inside, it'll be raw carbon so should show up pretty clearly if it's cracked.
Again thanks for the responses guys. I had chance to remove the seat post today and take some more pictures.
I still wonder if there is a small weakness or crack looking side on and there does seem to be a similarly shaped but very slight imperfection in the same area either side on the inside but the area looks fairly solid and feels smooth.
There didn't seem to be any noise or movement on removing and re-fitting the seat post.
What do you think?
I still wonder if there is a small weakness or crack looking side on and there does seem to be a similarly shaped but very slight imperfection in the same area either side on the inside but the area looks fairly solid and feels smooth.
There didn't seem to be any noise or movement on removing and re-fitting the seat post.
What do you think?
Cheers guys. I was inclined to take Gareth's approach- assuming people think it's unlikely to fail spectacularly or leave me in the situation where it's suddenly beyond repair I've taken pictures against a ruler, thought I'd compare regularly and if there's any sign it's worsening then attempt a DIY repair as I've had a bit of fibreglass experience and carbon fibre repairs don't look like rocket science from what I've seen on YouTube and other internet write ups.
Coin test.
With the seat post out of the frame, tap a few areas of the frame with a coin, well away from this area. Once you’re attuned to the noise, move closer to the area you’re concerned about. If it’s a crack the tone of the noise the coin makes will change, and it will sound more like when you put a cracked piece of china down on a hard surface.
Fwiw I think that is not a crack.
With the seat post out of the frame, tap a few areas of the frame with a coin, well away from this area. Once you’re attuned to the noise, move closer to the area you’re concerned about. If it’s a crack the tone of the noise the coin makes will change, and it will sound more like when you put a cracked piece of china down on a hard surface.
Fwiw I think that is not a crack.
Hugo Stiglitz said:
Bmx double collar seat collar? Or get x 2 seat collars?
On a carbon frame you can't really clamp the seat post any other way than as designed, otherwise at best it won't work, and at worst it will crack it even worse. Many modern frames have all sorts of intricate seat post mechanisms - my Colnagos have shaped posts and internal wedges you screw down using a hex bolt, praying that you are doing it correctly...
Gareth79 said:
On a carbon frame you can't really clamp the seat post any other way than as designed, otherwise at best it won't work, and at worst it will crack it even worse.
Many modern frames have all sorts of intricate seat post mechanisms - my Colnagos have shaped posts and internal wedges you screw down using a hex bolt, praying that you are doing it correctly...
My TCR seat pot clamp is like that and if it's not tight (as in right at the top of the stamped on torque range) it creaks, and you don't half feel nervous torqueing it up!Many modern frames have all sorts of intricate seat post mechanisms - my Colnagos have shaped posts and internal wedges you screw down using a hex bolt, praying that you are doing it correctly...
I’d ask a couple more questions if you OP.
How much do you weigh and how much of the seat post will be in the frame?
If you are relatively light and a good 66%-70% of the seat post will be clamped in the frame, unless you are planning on covering a lot of miles I think you will be ok with this.
I had a cracked carbon frame that I carried on riding whilst I waited for the warranty to be sorted and it was fine.
The other thing I’d recommend is marking the end of the crack with something to monitor it.
Otherwise it will be like the crack in our hallway ceiling that I keep getting told is getting worse when I’m sure it’s not..
How much do you weigh and how much of the seat post will be in the frame?
If you are relatively light and a good 66%-70% of the seat post will be clamped in the frame, unless you are planning on covering a lot of miles I think you will be ok with this.
I had a cracked carbon frame that I carried on riding whilst I waited for the warranty to be sorted and it was fine.
The other thing I’d recommend is marking the end of the crack with something to monitor it.
Otherwise it will be like the crack in our hallway ceiling that I keep getting told is getting worse when I’m sure it’s not..
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