Is "light weight" carbon wheel not strong enough for a hard braking?

[Tech72]

How often do you turn a wheel 80 degrees to emergency stop while travelling at a presumably high speed of 40+km/h? It is not an emergency braking maneuver and if he had continued straight, he would still have crashed but the dog would have been nastily injured and the wheel would have been absolutely fine. In a situation like that, there was no way to avoid crashing.

If you've ever lived in a decent size city and have had to fight traffic to reach the boondocks for a ride, the chance of having to do an e-stop involving turning the front wheel 80 degress while travelling at +40km/h is real and present. Thankfully not often, but it does occur. Ever had an idiot motorist cut you off? Ever had a car door open RIGHT in front of you? How about in a race where you've had to brake hard to avoid a crash or crashing into the guy in front of you on a downhill section? Similar speed, similar situation. Hopefully not a similar wheel buckling. I'm not dishing the Lightweights but any means. I'm just a little more weary of these super lightweight but fragile wheelsets out there.

 

[bobbyOCR]

Yeah, but I'd stop a little differently. Turning the wheel 80 degrees means your momentum wants to carry you forwards while your bike doesn't, and at an extreme direction change of 80 degrees you side load everything that has been turned and in most cases you will get thrown over anyway.

And LW aren't fragile. My good friend and shop owner (who is now getting LEWs in preparation for building a sub 5Kg 61cm Parlee Z$, gonna be nuts) decided to bunnyhop a branch for fun. They came out completely fine.

They can be used for cyclocross with no ill effects. In fact they are used extensively in cyclocross in Europe.

There is a picture of one of the Unibet riders, I think, or a LW sponsored pro (Erik Zabel? Alienator could help out here) taking a jump with lightweights and they came out fine.

 

[alienator]

If you turn the wheel 80 degrees while travelling 40kph, you're gonna crash. It's that simple. In fact, you'll be in the midst of your crash before your wheel ever gets to 80 degrees.

 

[531Aussie]

Yeah, but I'd stop a little differently. Turning the wheel 80 degrees means your momentum wants to carry you forwards while your bike doesn't, and at an extreme direction change of 80 degrees you side load everything that has been turned and in most cases you will get thrown over anyway.

Are you trying to get the distribution rights for these wheels? Why are you trying to defend them so vehemently on all the forums?The point is, that while we can't can't expect such wheels to withstand everything, I'd like to think they could withstand something, but they've shown they can withstand NOTHING. The bottom line is they failed far too easily

where do you keep getting 80 degrees from? It's barely past 45, even after it's already crumpled to dust.

When he's only about 3" from the dog, the wheel is barely off dead straight.

One inch from the dog, and the wheel is at about 15 degrees -- maybe less. The wheel hits at this angle then gets pushed to a greater anlge

the wheel hits the dog, THEN turns further and snaps at the same time. Even then it still hasn't got to 45 degrees. Look at his bars

 

[531Aussie]

back in my day, they made 'real' wheels

Phinney smashed into this car at a million miles an hour; the car is smashed, Phinney is smashed, the frame is smashed, but the front wheel is still round!! Hee hee hee hee

 

[pistole]

- got a question , why did the rider not plough straight into the dog ?

- turning the wheel that way seems a very dangerous way to force a stop.

- on a ride on Saturday , I had to e-brake for a pedestrian who ran across 2 lanes of an expressway. She did the left-right jig , I decided on a path (away from traffic) and braked both front and back brakes and leaned all the way back to avoid being thrown over my bars. If she jigged a couple of inches back from where she had come from , I would have hit her square on , which I think would have been better than swerving into traffic.

- oh yeah , I swore like a sailor at her ...

.

 

[alienator]

- got a question , why did the rider not plough straight into the dog ?

Maybe because he didn't feel like the dog was expendable? Why should he have plowed into the dog?

Why do riders try to avoid downed riders when they can? Why don't they just plow into the downed riders?

 

[531Aussie]

- got a question , why did the rider not plough straight into the dog ?
...

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he'd lost some control because his back wheel was locked and snaking somewhat

 

[hd reynolds]

These guys do this for a living. Whatever the rider did was possibly the best anybody can do given the circumstances. He and the dog came out OK altho the wheel didnt.

 

[bobbyOCR]

Are you trying to get the distribution rights for these wheels? Why are you trying to defend them so vehemently on all the forums?The point is, that while we can't can't expect such wheels to withstand everything, I'd like to think they could withstand something, but they've shown they can withstand NOTHING. The bottom line is they failed far too easily

It's not that. It is the fact that these wheels were subjected to incredibly unusual forces for a wheel to suffer and everyone has instantly assumed that they are fragile **** that can withstand NOTHING. Which is ****. Thousands of people ride these wheels worldwide and you hear 98% praise. The only other cases are derailleurs getting into spokes, and other things that wheels were not designed to suffer.

So stop assuming that side loading a wheel to breaking point (especially since that is a one-piece carbon wheel (in essence, anyway) is an accurate test of its strength. Each one of those spokes can support 1200kg while still being lighter and stiffer than stainless steel. BUT ONLY VERTICALLY WHICH IS HOW A WHEEL IS MEANT TO BE DESIGNED.


Why am I even arguing this, I will not be able to afford them for aeons. I just hate people drawing incorrect conclusions.

It is like putting an 800kg hatch in a test with a 20t semi trailer, ramming it from the side, then calling the whole car unsafe.

 

[hd reynolds]

back in my day, they made 'real' wheels

Phinney smashed into this car at a million miles an hour; the car is smashed, Phinney is smashed, the frame is smashed, but the front wheel is still round!! Hee hee hee hee

Because Davis T-boned the car.. the wheel is stronger in that direction that's why its still intact.

 

[531Aussie]

Because Davis T-boned the car.. the wheel is stronger in that direction that's why its still intact.

you know that the wheel was EXACTLY perpendicular to the car? Everyone seems to know this. Uncanny

 

[hd reynolds]

you know that the wheel was EXACTLY perpendicular to the car? Everyone seems to know this. Uncanny

Its a no-brainer if you will examine the pic closely.

I'll give you a clue... look at the head tube and downtube of the bike where it meets the headtube.

 

[531Aussie]

so,the wheel has the be perfectly perpendicular the inflict that downtube damage? The tyre ends up on the right side of the bottom bracket -- maybe this means the wheel was off to the left. Maybe the wheel was on the same "MASSIVE" angle as Burghardts. Either way, I won't believe anything unless it comes from Phinney himself.

Anyway, it's somewhat irrelevant, because, anlges or no angles, what about the the fact that Pinney's impact force was about 50 trillion times that of Burghardt's?

 

[531Aussie]

It's not that. It is the fact that these wheels were subjected to incredibly unusual forces for a wheel to suffer and everyone has instantly assumed that they are fragile **** that can withstand NOTHING. Which is ****. Thousands of people ride these wheels worldwide and you hear 98% praise. The only other cases are derailleurs getting into spokes, and other things that wheels were not designed to suffer.
.

fair enough, but no-one could say that the above pic is "side on" impact

either way, this ain't good for business

 

[hd reynolds]

so,the wheel has the be perfectly perpendicular the inflict that downtube damage? The tyre ends up on the right side of the bottom bracket -- maybe this means the wheel was off to the left. Maybe the wheel was on the same "MASSIVE" angle as Burghardts.

Anlges or no angles, what about the the fact that Pinney's impact force was about 50 trillion times that of Burghardt's?

You made a selective snap of the video just to make your argument. If you examine the video again, the wheel buckled when it was almost perpendicularly lateral to the velocity of the rider.

Also even if you exagerate Phinney's impact to 1 gazillion times it don't make it an unbreakable wheel. There are other questions that come to mind about Phinney's misadventure including - why the fork remained intact while the downtube was pretzeled, etc, etc.

These 2 accidents have different circumstances.

 

[Skoorb]

If you turn the wheel 80 degrees while travelling 40kph, you're gonna crash. It's that simple. In fact, you'll be in the midst of your crash before your wheel ever gets to 80 degrees.

True. These are not cars. If you're braking hard on the front and turning at the same time, you're done, period.

It occurs to me that no wheel on the planet, as it's turned more and more, will be able to withstand these forces because essentially, say at a 90 degree turn, the hub is going forward and the wheel is being grabbed from the bottom--it will of course collapse on its side.

In this case, pre-collision, if there was bending there wasn't much, and we have no idea how much a non-light wheel would have bent. Certainly most of the bending was caused by the fact he hit a dog.

got a question , why did the rider not plough straight into the dog ?

Instinct; it was not the right thing to do necessarily, though in retrospect the dog did end up fine and he ended up fine so it all worked out

 

[531Aussie]

You made a selective snap of the video just to make your argument. ..

What? What the hell other shots could I have taken? I took the last 3 frames (as best I could) before impact (the last shot is the point of impact)

If you examine the video again, the wheel buckled when it was almost perpendicularly lateral to the velocity of the rider

the wheels is breaking here, right at the point of impact, and you can't exactly say the wheel is sideways.

Also even if you exagerate Phinney's impact to 1 gazillion times it don't make it an unbreakable wheel. There are other questions that come to mind about Phinney's misadventure including - why the fork remained intact while the downtube was pretzeled, etc, etc.

These 2 accidents have different circumstances.

I posted the Phinney mostly as a gag, and an extreme example of a wheel survivng enormous impact. I put it on other forums because several people claim that "no wheel on Earth" would've survived the crash with the dog, which is a farkin joke! This is obviously an example of a wheel suriviving massive impact, perpendicular or not

The point IS that the Lightweight folded far too easily, and a bazillion other wheels would've survived it -- probably even a bazillion other carbon wheels. If people wanna take the enormous risk, then fair enough; at least now they know

 

[hd reynolds]

What? What the hell other shots could I have taken? I took the last 3 frames (as best I could) before impact (the last shot is the point of impact)


the wheels is breaking here, right at the point of impact, and you can't exactly say the wheel is sideways.


I posted the Phinney mostly as a gag, and extreme eg of a wheels survivng enormous impact. I put it on other forums because several people claim that "no wheel on Earth" would've survived the crash with the dog, which is a farkin joke!

The point IS that the Lightweight folded far too easily, and a bazillion other wheels would've survived it -- probably even a bazillion other carbon wheels. If people wanna take the enormous risk, then fair enough; at least now they know

Well if that’s what you believe nobody can sway you about that. Maybe until you actually test or experience and 'endo' like that will you believe otherwise. The fact is a bike wheel can only take so much lateral punishment and people who have been active in cycling long enuf and seen these types of failures will disagree with you.

FWIW, the video is in slow-mo and taken from the back. It does not really show the speed the rider was travelling. Hence, that is why you keep marvelling as to how fantastic Phinney's accident was (aside from the smashed back window, buckled frame etc).

 

[531Aussie]

didn't an Euskatel rider similarly smash into a fallen Credit Agricole rider just a couple of hours ago? Why didn't his front wheel collapse?