Why so many punctures!

gingerrob25

After watching the downhill WC at Windham this weekend and seeing various riders get punctures I was thinking about how irritating it must be to get a flat in the middle of your race...

That got me thinking... how come these guys are riding round on thousands of pounds worth of bike, with all sorts of technical parts, yet still no one has yet bothered to develop a solution to punctures?
An issue that have been around ever since biking began

I guess it would be difficult to completely solve punctures, and they have made tubeless tyres, but as the commentator on Red Bull TV said, they are still very able to get flats.

How come no serious progress has been made in eliminating the menace that is the puncture?

nicklouse

They tend to get flats through taking the wrong line.

And they tend to be tyres coming unseated rather than punctures. Though snakebites still happen again through not taking the lines they planed to.

Chunkers1980

Of course it's possible to stop punctures 100%. It's a trade off.

ricardo_smooth

Chunkers1980 wrote:

Of course it's possible to stop punctures 100%.

Bull.

Nobody can 100% stop a puncture on a DH bike and still keep the bikes safe. Even if they ran things at 60 psi I guarantee you somebody would still flat

Chunkers1980

Not if it was completely over engineered and bonded to the wheel. Would you want to use it? Would you win? No.

ricardo_smooth

I suppose your statement of 100% stopping a puncture is strictly true (tank tracks, solid wheels to name a couple of ridiculous solutions )

I don't think punctures will ever be 100% erradicated from any kind of sport where speed is involved, surely with the money in motorsports, this would have been done by now if it were possible, then it would eventually trickle down to MTB

ilovedirt

As Nicklouse said, punctures come from taking the wrong line or making simple mistakes. You can't prevent punctures 100%.

paul.skibum

I think it should be possible to develop a cellular system where there are many small air cells inside the tube that can in some way be inflated as one unit but once inflated the cells seal so an individual puncture only impacts a very small part of the tube.

Only problem is how they then deflate to remove a wheel! Can you tell I am not an engineer.

Some of the XC riders on Saturday were running tubular tyres where the tyre is effectively a heavy duty innertube bonded to the wheel rim but they still got flats if they tore the tyre sidewall which I guess were still relatively thin for xc racing weights.

YeehaaMcgee

Has anybody experimented with foam for tyres? Different densities of foam could equate to differing air pressures.

Chunkers1980

They defo did years back. Wonder if they'd work better now we have air FS?

paul.skibum

That's kind of what I was thinking.

Using the tubular idea but foam filled so the tyre comes ready to spoon onto a rim, bond in place and you are ready to rock - trouble is you'd have to make it removable when it wore out but not removable when riding!

cooldad

Nope, they'd have to be virtually solid. Tyres work in a similar way to spokes, it's the top bits that hold the bike or whatever up, while the bottom deforms over irregularities.
Foam filled tyres would (or do because you can get them) just bounce off bumps.

cooldad

Not sure that makes sense but I know what I'm trying to say, just not very clearly.

cooldad

Earliest tyres had multiple tubes - maybe that's what we need. One goes you still get home.

YeehaaMcgee

Hmm, really? I didn't know tyres worked like that.
I'm sure I read somewhere that, counter-intuitively, spokes do not work as you describe them. I don't quite believe it though, I'm still sticking with the "hub hangs off the spokes" view of the world.

cooldad wrote:

Earliest tyres had multiple tubes - maybe that's what we need. One goes you still get home.

And if they all go, you've got a hell of a puncture repair job

cooldad

YeehaaMcgee wrote:

Hmm, really? I didn't know tyres worked like that.
I'm sure I read somewhere that, counter-intuitively, spokes do not work as you describe them. I don't quite believe it though, I'm still sticking with the "hub hangs off the spokes" view of the world.

cooldad wrote:

Earliest tyres had multiple tubes - maybe that's what we need. One goes you still get home.

And if they all go, you've got a hell of a puncture repair job

That's what I was trying to say. Tyres work the same way, it's the air in the top holding you up, the bit in the bottom providing grip and suspension.

Still sounds like I'm drunk though.

karlbrewster

Let's look at it this way: Handling punctures will always be a part of the race.
Kind of like changing tyres during an F1 race. It slows you down yes... but you gotta deal with it.

paul.skibum

what about making the foam filled tyres semi porous so air can still move around inside but have a sealant style goo in there that seals up the pores in the event of a failure giving you at least some remaining support for the remainder of a rate/run - clearly this is going to need some research and the tyres will be quite expensive........

gingerrob25

paul.skibum wrote:

I think it should be possible to develop a cellular system where there are many small air cells inside the tube that can in some way be inflated as one unit but once inflated the cells seal so an individual puncture only impacts a very small part of the tube.

Sounds like a pretty cool idea

mrmonkfinger

gingerrob25 wrote:

yet still no one has yet bothered to develop a solution to punctures?

Its a conspiracy to keep racing interesting by making riders have the odd puncture at crucial moments.

yeehaa wrote:

I'm still sticking with the "hub hangs off the spokes" view of the world.

The trick is that the hub hangs off every single spoke at the same time. You get minor (very very minor) deformation of the rim where the rim+tyre touches the ground, and the few spokes at that point become very very slightly looser and support the rim a tiny tiny bit little less - but they are still all supporting the hub.

If you deform the rim enough, the bottom few spokes can loosen off entirely - and that's when you get a pringle shaped wheel all of a sudden, the rest of the spokes just pull it straight out of shape.

mrmonkfinger

cooldad wrote:

Earliest tyres had multiple tubes - maybe that's what we need. One goes you still get home.

That's a whole lot of valves!

YeehaaMcgee

mrmonkfinger wrote:

The trick is that the hub hangs off every single spoke at the same time. You get minor (very very minor) deformation of the rim where the rim+tyre touches the ground, and the few spokes at that point become very very slightly looser and support the rim a tiny tiny bit little less - but they are still all supporting the hub.

Yes, I know this theory, that is in fact what I was trying to explain, and it's how I see it working.
HOWEVER, I've been told that if you actually measure the load on the spokes, it's actually the bottom ones that do the work.
As I said, I'm sticking with my (and your view) - cause I can be like that sometimes

cooldad

Just accept it's all magic and we float on air.

mrmonkfinger

cooldad wrote:

Just accept it's all magic and we float on air.

this guy never has punctures:

gingerrob25

mrmonkfinger wrote:

Its a conspiracy to keep racing interesting by making riders have the odd puncture at crucial moments.

Anonymous

paul.skibum wrote:

I think it should be possible to develop a cellular system where there are many small air cells inside the tube that can in some way be inflated as one unit but once inflated the cells seal so an individual puncture only impacts a very small part of the tube.

That was the idea with the Titanic.

What we need are hover wheels. Like a hover craft, blow air down the spokes.

YeehaaMcgee

I'll blow air down your spokes in a minute.