Drago
Legendary Member
- Location
- Suburban Poshshire
Not crashed? Well, I suppose MH370 could have been circling for 2 years.
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OP
OP
KneesUp
Guru
Thanks for all the replies.
I've worked this out now, after the same noise occurred twice on the way home - both downhill. I use a different water bottle for work then I do when I just ride my bike, and it's slightly slimmer. Slim enough that when you are going downhill it slides forward a bit, meaning that when you hit a pothole there is evidently enough bottle sticking out the cage to give it enough leverage to smack against the down tube making a quite alarming noise. I put the bottle in my bag and it didn't do it again.
I've worked this out now, after the same noise occurred twice on the way home - both downhill. I use a different water bottle for work then I do when I just ride my bike, and it's slightly slimmer. Slim enough that when you are going downhill it slides forward a bit, meaning that when you hit a pothole there is evidently enough bottle sticking out the cage to give it enough leverage to smack against the down tube making a quite alarming noise. I put the bottle in my bag and it didn't do it again.
Wobblers
Euthermic
- Location
- Minkowski Space
Papier mâché would be "just another frame material" too. Still doesn't mean I want to ride it!
Do aircraft wings and F1 chassis fail gracefully or suddenly? Or do you mean to say that you think all carbon fibre behaves the same or something?
Interestingly, papier mâché has the same strength and stiffness as steel, weight for weight. It would make an excellent engineering material, if it were waterproof. Its strength comes from the cellulose fibres it's composed of - just like wood. Your weight is most likely being supported by a wooden floor right now - but I suspect you don't worry about falling through it!
The fact is, any material can fail catastrophically and suddenly. It is a pernicious myth that steel is somehow exempt from the realities of materials science. Yet there are any number of engineering disasters that can be attributed to its abrupt failure. The collapse of the Silver Bridge comes to mind (due to the failure of a single eyelet bolt through stress corrosion cracking, IIRC). If you overload any material it will fail suddenly.
American Airlines flight 587 crash in 2001 was due to an overloaded carbon fibre rudder breaking off. It was subject to over 3 times its design load, and even then it was the metal fasteners to the fuselage that failed. Carbon fibre is a lot stronger, and more resilient than most realise.
@KneesUp I commute on a bike, over some rather rough roads, with a carbon fibre fork. I've certainly crashed through some nasty potholes. It's never been the frame that's worried me, but the wheels, as they're less strong than the forks. Given that the rim experiences the full force of the impact, and the forces on the fork will be damped somewhat by the spokes flexing, if your wheels are still true, it's unlikely that your fork will have come to harm.
Hacienda71
Mancunian in self imposed exile in leafy Cheshire
- Location
- Wilmslow, Cheshire
S-Express
Guest
I think you're getting confused. No 787s have been lost yet. You are mixing up with the 777, which doesn't have much in the way of carbon composite use anyway.
F1 suspension component failure is hardly a modern phenomenon, so the use of carbon components is mildly irrelevant in that context.
I wouldn't take alot of refuge in this video to prove which material is better. - The first test proves it alone.
at 900 lbs the alloy top/downtube start necking,
and at the same pressure the carbon frame starts delamanting internally - you can hear individual fibers breaking away, this wouldn't make it safe to ride in the test of time, though that can vary.
The drop test would also lead to the same results.
But as for all reading, Carbon itself is only as strong as its design, which, is part why it had gotten such a bad rap from the beginning. Advances in the technology are amazing, but you need to remember one thing, that is often underlooked
Typically, as you go up in price with carbon for Bicycles you'll find the material becomes lighter & stiffer, and ultimately more impractical for riding use because its lower elongation and higher modulus makes it more brittle, the more expensive you get the less material you get to counter imperfections in the materials aswell.
Infact, this is true for alloy bikes aswell, but thanks to butting technology even an expensive lightweight alloy frame would be more practical for harsher uses, as the weld joints are eased from the pressure from riding load and impact because of the flex in the butted tubes. - I read a very lovely article about it once on another forum, i'll see if i can dig it up and post the link in here.
Anyway, the "standard" grade of carbon that is commonly used in entry level bikes is actually pretty amazing when looked in comparison to the higher-tier carbon bikes. Just look at the bog-standard Boardman Team carbon. - That grade of carbon (as found on many standard carbon forks) would have More flex and More material to complement any imperfections, making it a more practical use of a Bike when compared to the Much higher-tier pro bikes.
Because in my mind, if any bike/vehicle can't get dropped, dent or scuffed without being written off is just simply not suited to be a vehicle at all.
Some say when you put enough force through a carbon frame to delamante or break any individual fibers, you've started a stress-riser that puts more pressure on the surrounding fibers and thus starts a "clock" on the life expectancy of your frame before it gives up completely.
But that depends if youve had a good solid impact on a high-stress area of your carbon frame, any small marks or weak impacts on a low stress areas would seldom hurt the more common grades of cheaper carbon as it would metals.
Personally, I'd never ride a carbon frame, because I know at some point I'll drop it or do something stupid - that, anyone will do because we're Humans, and if it's not you who causes the mistake, it'll be another pedestrian or cyclist, who won't be paying for the damage.
But in reality, a cheaper low-end carbon bike would stand up to that use just fine anyway, so who knows! maybe i'll switch after my alloy bike dies, But that's unlikely if all goes to plan.
On a final irrelevant sidenote- carbon can be repaired, which means if you love your frame enough, it CAN be fixed. But, sadly it is still expensive to fix carbon frames, so, you'll probably have to buy a new frame in either case.
Alu frames can ALL be welded, but the strength is... Not so consistent through all types of alu, making it more of a gamble, the pricing is generally cheaper but most times not enough to justify the odds that your frame may just break around the repair again.
but in respect to the OP, I too found out my forks where happy to be "Used" in such a way, but I also found out that they are happier to be "Used" with a decent sized tire that my frame would accommodate.
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gbb
Legendary Member
- Location
- Peterborough
Is the headset well adjusted ?
A former bike of mine suffered a horrible cracking noise when going over any larger bumps, I was convinced the forks were going to fail
.
Took it to my LBS and he properly adjusted the headset. It had seemed ok to me but as he explained, full carbon fork bungs sometimes require the front wheel to be given a firm bump on the floor to get everything to sit right while adjusting..
No problem after he did this.
Just a possibility for OP
A former bike of mine suffered a horrible cracking noise when going over any larger bumps, I was convinced the forks were going to fail
.Took it to my LBS and he properly adjusted the headset. It had seemed ok to me but as he explained, full carbon fork bungs sometimes require the front wheel to be given a firm bump on the floor to get everything to sit right while adjusting..
No problem after he did this.
Just a possibility for OP
Disabledcyclist40
Well-Known Member
Not a 787 though
Hacienda71
Mancunian in self imposed exile in leafy Cheshire
- Location
- Wilmslow, Cheshire
That was not the point of posting it. It was to show the op that carbon is fine for commuting on. I personally don't have a preference I have aluminium bikes, carbon bikes and steel bikes. I just get a bit bored of people saying if a carbon bike falls over it is a write off.
S-Express
Guest
Your point being what, exactly?
I know, but that video is entirely misleading you don't want the OP To start assuming carbon is better than alloy and then abuse it as a result.
S-Express
Guest
The vid is not misleading - in fact it couldn't be more straightforward. It is intended to highlight the differences in breaking force and that's what it does.
S-Express
Guest
Absolutely nothing, just piss taking
You need to try harder then.. The BAe 146 in the pic is an 'all metal' airframe...
