>> ^gorillaman:

Four seconds is actually pretty slow by modern F1 standards.


Slow? Seems pretty quick to my mind, based on memory of what F1 pits are like. This looked like a tyre change so no fuel being put in - could they really get much faster?

Yeah, he used a CO2 canister-based pump. Very handy for quick changes, but you need to be careful to do as he do and aim upwards when inflating (downward facing = greater chance of freezing inner tube - from experience). Note: Depending on temperatures and canister size (12g, 16g etc), CO2 canisters often only get you back up to 80-90PSI, which may or may not be enough for your setup


This was a great (and impressive) display. As someone who has changed HUNDREDS of flatties, my ramblings, FWIW:
- The tyre/rim combo can often mean removal (and reseating) of the tyre is a PITA, due to slightly small ID tyre bead and slightly oversize RIM OD. Inevitably this requires n+1 tyre levers, with n being the number you have in your pocket (tip: wheel quick releases make good emergency tyre levers at a pinch)
- 30 seconds spent identifying/removing source of puncture (glass/wire/thorn) saves many minutes of rework when you get another puncture a minute later from the bastard wire strand you didnt look hard enough for
- always carry a patch kit (or 1-2 of the self-adhesive sticky instant patches). Two punctures on one ride is rare but it happens and being stranded out of cell coverage then trying to peel off bar tape to seal a puncture is a way to ruin a good ride
- Replace old tyres. There is an exponential growth curve that describes the relationship between tyre age to incidence of punctures. Old tyres are the single most effective way to spend lots of time on the side of the road yelling

>> ^rottenseed:

So the limiting reactant would be the starter fluid and the air in the tire. Oxygen to be more exact. Because you want enough forces to seat the tire, but not so much it removes all of the gases from the tire, maybe they should have tried less starter fluid. If that's depleted in the reaction quickly leaving enough energy to seat the tire, but also enough oxygen left over from the reaction, you might end up with a working tire.
Somebody please double check my thought process, but I think it's definitely worth more experimentation.

Would be one to test, but I think you'd end up with the same problem. End of the day to jump the tyre back on the rim you are going to be filling quite a lot of the inside of that tyre with the hot gases from the combustion. You might get less deflation with less accelarant, but I'd think you'd start with a lower pressure within the tyre even before the gases cool, so you wouldn't gain much. Thats my guess anyway.


Now maybe if you did this, and at the same time dropped just the right amount of dry ice in with it you could get the tyre back on the rim AND get it pressurised without the need for some sort of pump. Ofc, dry ice is not exactly something you tend to have stored in the glove compartment...

>> ^maestro156:

So maths ...
according to this website: http://www.csgnetwork.com/stopdistinfo.html, a vehicle slows at roughly 15 feet per second per second, which means in the 0.2 seconds that it takes the bike rider to discover that the truck is braking, the speed of the 90km/h truck would have reduced to about 86-87km/h
which means while the bike will travel 5m in those 0.2 seconds, the truck will travel about 4.8m, putting him 20cm closer to the truck.
Once again, too close for my comfort, but I don't think I'd call it stupid. Just risky, like base jumping and wingsuits.


Adding to the maths frivolities there are some factors that need to be considered....

1) It is a 5 axle truck (they usually have 18 wheels)
2) We don't know if the truck is loaded or not
3) The friction coefficient of bicycle tyres is about 0.75
4) The friction coefficient of truck tyres is about 0.8

If the truck is fully loaded the stopping distance is going to be very far - probably well farther than the bicycle.
If the truck is empty the stopping distance will be a lot less than the bicycle (18 wheels at a higher friction coefficient = stopping on a figurative dime).
So unless we know more information, the calculations are guess work with a very wide margin of error.

>> ^CaptainPlanet:

as maestro has astutely pointed out, you've errantly assumed this truck can full stop in zero time. Hurp de durp de durpidy pthhhhhhhhhhh
>> ^Jinx:
>> ^maestro156:
Seems likely to me that he'd be able to brake faster than the truck could break, and if the truck started pulling too far away leaving him exposed, he could coast on the shoulder till he can safely stop.
I'm not saying I would do this, but it doesn't seem all that dangerous. I guess the one thing to worry about would be road debris, since he can't see it coming.

I dont think its about who can stop the fastest, its about how fast you can start stopping.
He's about half a metre away from the back of that truck. He's doing 90kph. Human reaction time is about .2 of a second. Lets do the maths.
90,000m/3600s = 25m/s
25m/s 0.2s = 5m
He's going to travel 5 metres before he even starts slowing down. If that truck has to brake hard he will go into the back of it. Granted, his speed relative to the truck won't be very high but it would prolly be enough to send him arse over tit. at close to 90kph. and he aint exactly in leathers.
I'm not even sure he could stop faster than the truck. Sure, the truck is heavier, but it has 4 wheels, big thick tyres and a lower centre of gravity. Lets do the maths.
The coefficient of friction between road bike tyres and average russian tarmac is...no I kid.


No I didn't? I just assumed the truck would slow enough that he could go into the back of it. So ok, the truck travels 4.8ms, the bike travels 5m. He's now 30cms from the back of the truck, and only now is he gonna start braking. Assuming they decelerate about the same, and I'm not even sure you can stop faster than a truck on a bike, there is still a 3m/s difference in speed with 30cms of room between them. Like I said before, he won't be going very vast relative to the truck when he collides, but his wheels are still going to be spinning prty quickly and I'd guess that would be enough to put him on the pavement...or you know, the risk is large enough that I wouldn't want to try it.


And this is ignoring all the myriad other risks from travelling at 90kph blind. Maybe his attention is on somebody in a car with a video camera in the lane next to him, and suddenly his reaction to the truck braking is delayed...maybe a pothole appears under the truck. Or a puddle. I'd rather base jump than do that.

as maestro has astutely pointed out, you've errantly assumed this truck can full stop in zero time. Hurp de durp de durpidy pthhhhhhhhhhh

>> ^Jinx:

>> ^maestro156:
Seems likely to me that he'd be able to brake faster than the truck could break, and if the truck started pulling too far away leaving him exposed, he could coast on the shoulder till he can safely stop.
I'm not saying I would do this, but it doesn't seem all that dangerous. I guess the one thing to worry about would be road debris, since he can't see it coming.

I dont think its about who can stop the fastest, its about how fast you can start stopping.
He's about half a metre away from the back of that truck. He's doing 90kph. Human reaction time is about .2 of a second. Lets do the maths.
90,000m/3600s = 25m/s
25m/s 0.2s = 5m
He's going to travel 5 metres before he even starts slowing down. If that truck has to brake hard he will go into the back of it. Granted, his speed relative to the truck won't be very high but it would prolly be enough to send him arse over tit. at close to 90kph. and he aint exactly in leathers.
I'm not even sure he could stop faster than the truck. Sure, the truck is heavier, but it has 4 wheels, big thick tyres and a lower centre of gravity. Lets do the maths.
The coefficient of friction between road bike tyres and average russian tarmac is...no I kid.

>> ^maestro156:

Seems likely to me that he'd be able to brake faster than the truck could break, and if the truck started pulling too far away leaving him exposed, he could coast on the shoulder till he can safely stop.
I'm not saying I would do this, but it doesn't seem all that dangerous. I guess the one thing to worry about would be road debris, since he can't see it coming.

I dont think its about who can stop the fastest, its about how fast you can start stopping.

He's about half a metre away from the back of that truck. He's doing 90kph. Human reaction time is about .2 of a second. Lets do the maths.

90,000m/3600s = 25m/s
25m/s*0.2s = 5m

He's going to travel 5 metres before he even starts slowing down. If that truck has to brake hard he will go into the back of it. Granted, his speed relative to the truck won't be very high but it would prolly be enough to send him arse over tit. at close to 90kph. and he aint exactly in leathers.

I'm not even sure he could stop faster than the truck. Sure, the truck is heavier, but it has 4 wheels, big thick tyres and a lower centre of gravity. Lets do the maths.

The coefficient of friction between road bike tyres and average russian tarmac is...no I kid.

>> ^Asmo:

>> ^EMPIRE:
I don't know what you're thinking, but I'm thinking someone placed that metal mesh over the hole so that cars could go over the hole, but the mesh actually got caught in the hole, and levered the car up.

Umm, the video makes it pretty clear.
The front left tyre goes in to the hole, smashes in to the far side and the ass end of the car rises as the front dramatically decelerates...

Nope. Watch the second video (in eric3579's post above) on 720p and you can better see what happens.

The manhole has an off-center metal mesh cover welded to a cylinder that fits down into the manhole (presumably to keep the mesh in place).
The front-left tire clips the side of the mesh cover, presumably just enough to pop it up. That's what catches the undercarriage and vaults the back end up.
The structure of the mesh-cylinder apparatus is more apparent at the end of the video when it settles near the hood of the vehicle.

>> ^EMPIRE:

I don't know what you're thinking, but I'm thinking someone placed that metal mesh over the hole so that cars could go over the hole, but the mesh actually got caught in the hole, and levered the car up.


Umm, the video makes it pretty clear.

The front left tyre goes in to the hole, smashes in to the far side and the ass end of the car rises as the front dramatically decelerates... Same sort of force applied as jamming on the front brakes of a bike and the back of the bike rises.

It would be difficult to see the lack of a dark metal manhole over a dark hole at speed when you aren't distinctly looking for it.

Dont be angry Enzoblue, JPM floundered a bit last season but its his choice/job/challenge/idea of fun (in most motor racing you need to be in the right team at the right time to win regularly).
The only big thing wrong in nascar+JPM IMHO is a bit of an attitude problem (like in Paybacks comment).

Notice what is said. Culprit first reacts to what he actually saw:
"I saw sparks coming from under the car as if it had a tyre down or something."
Looks like something broke. Likely a wheel/tyre/suspension/pit crew/previous contact problem.
And then he thinks it over and tries to come up with a more popular angle:
"I just wonder if Montoya was going down the back catching up with the field and he didnt know the safety truck was up there and they called him on the radio.."
Look ma he hit the big yellow track dryer on the end of the straight, he must be blind/stupid/distracted and dangerous. LOL

JPMs slightly awkward comment about the truck driver looking scared (not in this video) was funny too.

Side impacts are nasty. Don't think you can expect to survive a collision like that regardless of your cars safety rating. I don't think I would have driven at those speeds in that weather even with the right tyres, especially given the lack of a crash barrier along the divider.

Silly question, but: ehm... winter tyres?


let me edit this some:
In pretty much all of europe you are required to have winter tyres during winter (duh), I guess there is no such thing in the USA, yes?

Hmm... well I don't think they hatch.

The car I was talking about looked a little like this one, only with no tinting and stock wheels and tyres... and Australian instead of Malaysian plates. Oh, and it wasn't as shiny and polished either.

In reply to this comment by ant:
Cars get born?

In reply to this comment by oritteropo:
... My first car was born in the year of the dragon :

It's been 2012 for 11 hours here, and even longer in NZ and (for the first time this year) Samoa, but not American Samoa, it will be the last place to celebrate.

My tour guide mentioned this happens a lot in European cities, specifically we were in Paris at the time.

Though I'd hate to think what this does to the transmission and the tread on the tyres, is it really worth it? Buy a scooter or something.