DCLane
Found in the Yorkshire hills ...
- Location
- Dewsbury, West Yorkshire
A carbon frame can be repaired; find a decent carbon repairer and it should cost less than £360.
Broken bike
- Thread starter shaftonred
- Start date
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cyberknight
As long as I breathe, I attack.
- Location
- Land of confusion
U
User10571
Guest
^
That's the people who repaired my frame.
If you want them to finish it with paint and stickers, that is where the bulk of what you pay will go - the repair itself is relatively cheap.
That's the people who repaired my frame.
If you want them to finish it with paint and stickers, that is where the bulk of what you pay will go - the repair itself is relatively cheap.
GrumpyGregry
Here for rides.
Whereas bike frames are very strong in normal use a toppling fall onto a hard object can, if you get unlucky, wreck a quality steel frame tube if the point of contact is the "wrong" place say on the top tube. So it ain't just carbon.
American forums are full of tales from folk whose carbon mtb frames have failed after falling off of roof racks or from getting trodden on.
American forums are full of tales from folk whose carbon mtb frames have failed after falling off of roof racks or from getting trodden on.
A lightweight bike falling over onto a plastic mower should at worst suffer nothing more than a paint scratch.
Almost every bike will fall over at some point in its life with little or no damage.
I would be asking the manufacturers to run through the benefits of carbon fibre and if they can explain why the cheap
plastic of a lawn mower suffered no damage yet the carbon frame is a write off.
I would certainly not be buying another frame if they claim that it can't tolerate such an insignificant fall....your weight wasn't even on it
so that's under 10 lbs falling 3ft at most.
I can't think of anything else that would break under such circumstances.
Sounds more like a manufacturing defect to me.
Almost every bike will fall over at some point in its life with little or no damage.
I would be asking the manufacturers to run through the benefits of carbon fibre and if they can explain why the cheap
plastic of a lawn mower suffered no damage yet the carbon frame is a write off.
I would certainly not be buying another frame if they claim that it can't tolerate such an insignificant fall....your weight wasn't even on it
so that's under 10 lbs falling 3ft at most.
I can't think of anything else that would break under such circumstances.
Sounds more like a manufacturing defect to me.
Globalti
Legendary Member
Not a manufacturing defect. As others have already explained very adequately, carbon is far far stronger than steel or aluminium if stressed in the intended directions. However like steel and aluminium if you apply a point impact to the tube wall it will bend and alloy and steel, being malleable, can take a dent without loss of overall strength especially if it's in the middle of a tube where stresses can flow through the dent smoothly - indeed some steel frames are deliberately "dented" on the chainstays to create space for the tyre or the chainring.
However carbon fibre is a brittle resin reinforced with carbon thread; immensely strong when stressed evenly as in a length of tube. A point impact will shatter the resin and the tube will become squashy, meaning that the carbon fibres are no longer held in alignment where they can carry the stresses so the frame is goosed. The broken section can be cut out and new resin and fibres bonded in, very successfully.
If the internet had existed before 1990 you'd have seen plenty of posts entitled: "Dropped my lightweight steel bike and dented the top tube! Help!" as a lightweight steel tube can dent almost as easily as a drink can.
However carbon fibre is a brittle resin reinforced with carbon thread; immensely strong when stressed evenly as in a length of tube. A point impact will shatter the resin and the tube will become squashy, meaning that the carbon fibres are no longer held in alignment where they can carry the stresses so the frame is goosed. The broken section can be cut out and new resin and fibres bonded in, very successfully.
If the internet had existed before 1990 you'd have seen plenty of posts entitled: "Dropped my lightweight steel bike and dented the top tube! Help!" as a lightweight steel tube can dent almost as easily as a drink can.
Nobody is disputing the fragility of a frame that's designed to take the stresses of riding.
What I am disputing though is that to have a lightweight bike keel over onto a plastic mower render it a write off.
I don't think that's acceptable.
It should be designed to withstand reasonable mishaps.
What I am disputing though is that to have a lightweight bike keel over onto a plastic mower render it a write off.
I don't think that's acceptable.
It should be designed to withstand reasonable mishaps.
snorri
Legendary Member
- Location
- East coast, up a bit.
It is designed to appeal to customers who want a lightweight bicycle and are prepared to treat it as such.
mattobrien
Guru
- Location
- Sunny Suffolk
I suspect it is designed to do the job for which it was intended, and possibly not much more.
It would be possible to make a carbon frame strong in all directions, but I suspect that may reduce some of the favourable properties of the material, lightness and flexibility where required.
I can imagine that it is about how thee force of he impact was transferred onto the frame, if the frame hit an edge of the lawn mower, then the force may hav been over a very small area and caused significantly more damage.
It's very unlucky, but possibly carbon frames can't be designed to take impacts in all places.
I agree with you regarding the point of impact, but lets be honest here, how much force could there possibly be when such a light bike keels over and hits plastic?
How does a carbon bike fare when hit with stones flung up from the road?
I really don't expect a carbon bike to be as robust as others for the reasons already explained but I also don't expect the frame to be written off after such a minor mishap.
