Which Tire Loses Traction First?

Quoted message said:

So there you are, zooming down an Alpine descent with a pair
of brand new identical tires, properly inflated. You dive
into the first turn, your inside pedal up, the pavement
perfect, the road clear, no braking needed in your opinion--

Oops! A bit too fast!

Hope you caught a glimpse of the skid marks.

Please take a moment to explain which tire lost traction
first and why.

The rear one.

Because I said so.

Quoted message said:

If you have time before the bottom of the cliff, please
describe what your other tire did.

Turned too far inward and eventually locked up.

Bill "again, because..." S.

Carl Fogel said:

So there you are, zooming down an Alpine descent with a pair of
brand new identical tires, properly inflated. You dive into the
first turn, your inside pedal up, the pavement perfect, the road
clear, no braking needed in your opinion--

Quoted message said:

Oops! A bit too fast!

Quoted message said:

Hope you caught a glimpse of the skid marks.

Your scenario is off reality. People who descend fast should know
that fast curves are always entered too fast, because braking in a
turn can reduce that speed safely while accelerating is not possible
because a pedal will strike the road if the curve is being taken fast.

Quoted message said:

Please take a moment to explain which tire lost traction first and
why.

That is not the way cornering crashes occur but when traction is
exceeded both tires go even if the break-out is initiated by only one.
The reason is that the lean angle increases in a slide and that
exceeds traction for both wheels if this is near the limit.

Quoted message said:

If you have time before the bottom of the cliff, please describe
what your other tire did.

I take it you are not a descender who rides near the limit or you
wouldn't ask. The comments of others on high speed descents involving
going over the bars is equally self incriminating.

Descending:

http://draco.acs.uci.edu/rbfaq/FAQ/9.15.html

Going over the bars:

http://draco.acs.uci.edu/rbfaq/FAQ/9.36.html

Jobst Brandt
[email hidden]

Quoted message said:

So there you are, zooming down an Alpine descent with a pair
of brand new identical tires, properly inflated. You dive
into the first turn, your inside pedal up, the pavement
perfect, the road clear, no braking needed in your opinion--

Oops! A bit too fast!

Been watching the "highlights" of the Beloki's crash in the '03 TDF have we?

I'd have to replay that one again to see what really happened, but I'm not
really inclined to do so. If there'd been no sound of him moaning as he lay
on the ground afterward, it wouldn't have been so bad.

Quoted message said:

Please take a moment to explain which tire lost traction
first and why.

If you have time before the bottom of the cliff, please
describe what your other tire did.

But from memory, I seem to recall that his problem may have started with his
front tire biting into the pavement a bit, causing his rear wheel to become
airborne, adding to his lack of control. With the front wheel no longer
pointing in the direction of travel, all was lost. But perhaps someone with
greater apetite for gore than I could re-watch the sequence and correctly
report what happened?

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

[email hidden said:

"]So there you are, zooming down an Alpine descent with a pair
of brand new identical tires, properly inflated. You dive
into the first turn, your inside pedal up, the pavement
perfect, the road clear, no braking needed in your opinion--

Oops! A bit too fast!

Hope you caught a glimpse of the skid marks.

Please take a moment to explain which tire lost traction
first and why.

If you have time before the bottom of the cliff, please
describe what your other tire did.

Thanks,

Carl Fogel

On a bike properly designed for that particular turn they commence skidding simultaneously on the neutral handling bike.

One the rear suspended recumbent the rear loses traction first because there are only two chainstays supporting the high rear bias weight, the chainstays do not provide sufficient torsional rigidity in a hard turn with a 230 lb rider so the rear is flexing in ways it isn’t supposed to.

On the road bikes, it’s the rear-probably insufficient rear weight bias.

On the folder the front- the rear weight bias and the rear suspension keep the rear knobby tires in better contact with the road than the unsuspended lightly weighted front.

On the unsuspended mountain bike – the front, rear weight bias keeping the tread in contact with the road.

On the electrics- the rear-the excessive rear weight bias means the rear sidewall can’t support the wide tire in a hard corner.

On the front suspended SWB recumbent the rear loses traction first.

Quoted message said:

Carl Fogel said:

So there you are, zooming down an Alpine descent with a pair of
brand new identical tires, properly inflated. You dive into the
first turn, your inside pedal up, the pavement perfect, the road
clear, no braking needed in your opinion--

Quoted message said:

Oops! A bit too fast!

Quoted message said:

Hope you caught a glimpse of the skid marks.

Your scenario is off reality. People who descend fast should know
that fast curves are always entered too fast, because braking in a
turn can reduce that speed safely while accelerating is not possible
because a pedal will strike the road if the curve is being taken fast.

Quoted message said:

Please take a moment to explain which tire lost traction first and
why.

That is not the way cornering crashes occur but when traction is
exceeded both tires go even if the break-out is initiated by only one.
The reason is that the lean angle increases in a slide and that
exceeds traction for both wheels if this is near the limit.

Quoted message said:

If you have time before the bottom of the cliff, please describe
what your other tire did.

I take it you are not a descender who rides near the limit or you
wouldn't ask. The comments of others on high speed descents involving
going over the bars is equally self incriminating.

Descending:

http://draco.acs.uci.edu/rbfaq/FAQ/9.15.html

Going over the bars:

http://draco.acs.uci.edu/rbfaq/FAQ/9.36.html

Jobst Brandt
[email hidden]

Dear Jobst,

We're all aware of what a wonderful descender you are. If we
forget, I'm sure that you'll remind us.

Feel free to change things to a flat paved road with no
descent if it makes you happier.

Braking was removed to reduce the question to pure
cornering.

If I were a descender, it would still be a question that you
failed to answer on your first try. Good luck on any
subsequent effort.

Which tire loses traction first and why? Or did you mean to
say that both tires invariably lose traction simultaneously?

Carl Fogel

Mike Jacoubowsky said:

Quoted message said:

So there you are, zooming down an Alpine descent with a pair
of brand new identical tires, properly inflated. You dive
into the first turn, your inside pedal up, the pavement
perfect, the road clear, no braking needed in your opinion--

Oops! A bit too fast!

Been watching the "highlights" of the Beloki's crash in the '03 TDF have we?

I'd have to replay that one again to see what really happened, but I'm not
really inclined to do so. If there'd been no sound of him moaning as he lay
on the ground afterward, it wouldn't have been so bad.

Quoted message said:

Please take a moment to explain which tire lost traction
first and why.

If you have time before the bottom of the cliff, please
describe what your other tire did.

But from memory, I seem to recall that his problem may have started with his
front tire biting into the pavement a bit, causing his rear wheel to become
airborne, adding to his lack of control. With the front wheel no longer
pointing in the direction of travel, all was lost. But perhaps someone with
greater apetite for gore than I could re-watch the sequence and correctly
report what happened?

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

Dear Mike,

Sorry, but I'm rolling riders from rec.bicycles.tech over
hypothetical cliffs by putting them into smooth corners too
fast with no braking.

Tour de France riders limited to shabby actual roads and
boring real crashes are of no concern.

Let others worry about whether Beloki's tire came off or he
hit some tar.

Let Armstrong figure out what happens when he tries
purse-snatching.

I just want to know which tire does what in a purely
hypothetical situation when a bike with no braking applied
goes into a corner too fast.

Consider the brake cables cut if necesssary, the tires
perfect, and the rider just hopelessly trying to turn more
sharply than is possible.

With that in mind, does the front tire still dig in instead
of losing traction and flip the rear wheel up into the air?
That is, rear tire loses traction first?

Carl Fogel

Quoted message said:

With that in mind, does the front tire still dig in instead
of losing traction and flip the rear wheel up into the air?
That is, rear tire loses traction first?

Yes.

Bill "assuming no sand" S.

meb said:

Quoted message said:

So there you are, zooming down an Alpine descent with a pair
of brand new identical tires, properly inflated. You dive
into the first turn, your inside pedal up, the pavement
perfect, the road clear, no braking needed in your opinion--

Oops! A bit too fast!

Hope you caught a glimpse of the skid marks.

Please take a moment to explain which tire lost traction
first and why.

If you have time before the bottom of the cliff, please
describe what your other tire did.

Thanks,

Carl Fogel

On a bike properly designed for that particular turn they commence
skidding simultaneously on the neutral handling bike.

One the rear suspended recumbent the rear loses traction first because
there are only two chainstays supporting the high rear bias weight, the
chainstays do not provide sufficient torsional rigidity in a hard turn
with a 230 lb rider so the rear is flexing in ways it isn’t supposed
to.

On the road bikes, it’s the rear-probably insufficient rear weight
bias.

On the folder the front- the rear weight bias and the rear suspension
keep the rear knobby tires in better contact with the road than the
unsuspended lightly weighted front.

On the unsuspended mountain bike – the front, rear weight bias keeping
the tread in contact with the road.

On the electrics- the rear-the excessive rear weight bias means the
rear sidewall can’t support the wide tire in a hard corner.

On the front suspended SWB recumbent the rear loses traction first.

Dear Meb,

And here I thought I was ruthless!

You're rolling seven bikes and riders over my cliff--thanks!

I take it that weight bias and suspension are what you
consider the decisive factors, not anything like the front
tire's steering load.

To sum up, you see the rear tire losing traction first on
five kinds of bikes, the front tire losing traction on an
unsuspended mountain bike, and both tires simultaneously on
a hypothetically properly-designed hypothetical bike.

Does the slope affect this weight bias? That is, if we
sprint into a corner too fast on a flat course, will that
make a difference?

And roughly what kind of front/rear weight biases would you
have in mind?

Thanks,

Carl Fogel

meb said:

On a bike properly designed for that particular turn they commence skidding simultaneously on the neutral handling bike.

One the rear suspended recumbent the rear loses traction first because there are only two chainstays supporting the high rear bias weight, the chainstays do not provide sufficient torsional rigidity in a hard turn with a 230 lb rider so the rear is flexing in ways it isn’t supposed to.

On the road bikes, it’s the rear-probably insufficient rear weight bias.

On the folder the front- the rear weight bias and the rear suspension keep the rear knobby tires in better contact with the road than the unsuspended lightly weighted front.

On the unsuspended mountain bike – the front, rear weight bias keeping the tread in contact with the road.

On the electrics- the rear-the excessive rear weight bias means the rear sidewall can’t support the wide tire in a hard corner.

On the front suspended SWB recumbent the rear loses traction first.

On the bikes having the rear break first, I try and correct by turning the front wheel back in the opposite direction.

I did inspect my skid marks in a recumbent fall last year in which the rear lost traction-the front tire tracked a wobbly line down the bike path, the rear skid circled the front. The pedal joined the tires to complete my tripod with its marks also circling the front. I don't know if I applied brake to the front but suspect I didn't have time to. The bike was facing the opposite direction at the end of the fall from which it started.

[email hidden said:

"]On Sat, 4 Sep 2004 14:51:55 +1000, meb

Quoted message said:

Quoted message said:

So there you are, zooming down an Alpine descent with a pair
of brand new identical tires, properly inflated. You dive
into the first turn, your inside pedal up, the pavement
perfect, the road clear, no braking needed in your opinion--

Oops! A bit too fast!

Hope you caught a glimpse of the skid marks.

Please take a moment to explain which tire lost traction
first and why.

If you have time before the bottom of the cliff, please
describe what your other tire did.

Thanks,

Carl Fogel

On a bike properly designed for that particular turn they commence
skidding simultaneously on the neutral handling bike.

One the rear suspended recumbent the rear loses traction first because
there are only two chainstays supporting the high rear bias weight, the
chainstays do not provide sufficient torsional rigidity in a hard turn
with a 230 lb rider so the rear is flexing in ways it isn’t supposed
to.

On the road bikes, it’s the rear-probably insufficient rear weight
bias.

On the folder the front- the rear weight bias and the rear suspension
keep the rear knobby tires in better contact with the road than the
unsuspended lightly weighted front.

On the unsuspended mountain bike – the front, rear weight bias keeping
the tread in contact with the road.

On the electrics- the rear-the excessive rear weight bias means the
rear sidewall can’t support the wide tire in a hard corner.

On the front suspended SWB recumbent the rear loses traction first.

Dear Meb,

And here I thought I was ruthless!

You're rolling seven bikes and riders over my cliff--thanks!

I take it that weight bias and suspension are what you
consider the decisive factors, not anything like the front
tire's steering load.

To sum up, you see the rear tire losing traction first on
five kinds of bikes, the front tire losing traction on an
unsuspended mountain bike, and both tires simultaneously on
a hypothetically properly-designed hypothetical bike.

Does the slope affect this weight bias? That is, if we
sprint into a corner too fast on a flat course, will that
make a difference?

And roughly what kind of front/rear weight biases would you
have in mind?

Thanks,

Carl Fogel

On the rear suspended folder I had the front tire losing traction so (4:2, not 5:1).

I don't have bikes with a near 50-50 weight distribution so those cited factors would seem to overshadow steering load.

Travelling downhill would shift weight but not mass to the front, so it would generally shift traction from the rear to the front.

If you are decelling in a corner due braking you are shifting weight but not mass forward, shifting bite to the front from the rear. (Trail-brake-steer in motorsports).

If decelling due aero drag, you are shifting weight to the rear, shifting adhesion from the front the rear.

meb said:

On the rear suspended folder I had the front tire losing traction so (4:2, not 5:1).

I don't have bikes with a near 50-50 weight distribution so those cited factors would seem to overshadow steering load.

Travelling downhill would shift weight but not mass to the front, so it would generally shift traction from the rear to the front.

If you are decelling in a corner due braking you are shifting weight but not mass forward, shifting bite to the front from the rear. (Trail-brake-steer in motorsports).

If decelling due aero drag, you are shifting weight to the rear, shifting adhesion from the front the rear.

The road bikes have a reasonably close f/r weight distribution, slick tires, no frame suspension and frames that handle the side loads.
Since the rear breaks first, there must be another reason on that type bike.

Quoted message said:

So there you are, zooming down an Alpine descent with a pair
of brand new identical tires, properly inflated. You dive
into the first turn, your inside pedal up, the pavement
perfect, the road clear, no braking needed in your opinion--

Oops! A bit too fast!

Hope you caught a glimpse of the skid marks.

There won't be any.

Quoted message said:

Please take a moment to explain which tire lost traction
first and why.

Probably the rear, by a small fraction of a second. As soon as it
loses traction, the rider and bike starts to fall toward the pavement;
this increases the angle of the remaining tire to the road surface,
washing it out immediately as well. It really matters little which
one slips first; once one's sliding, the other will lose traction as
well. If you go in too fast to brake without breaking traction,
you're *way* too fast, and you're probably going down.

People who ride incautiously in a hilly area as a result of habits
ingrained after years of living in a very flat place often discover
this feature of curves in dramatic fashion.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Quoted message said:

With that in mind, does the front tire still dig in instead
of losing traction and flip the rear wheel up into the air?
That is, rear tire loses traction first?

Have you not watched MotoGP? Or at least the crashes from it? It's
invariably a lowside or highside.

I lowsided on campus a few years back on the road bike... there was sand in
a corner, and the damage was light road rash at about 25+mph. It was very
calm and progressive... I was leaned over so far that my body only had about
30 more degrees to fall to reach the ground.

I've highsided my mountain bike in a similar spot, but only because I
steered too fast... I was leaned over at maybe 50 degrees or so, and then
quickly tried to flick back up to vertical. Except it happened really fast,
throwing me high into the air. The landing hurt... so I just try to lowside
now.

My response had nothing to do with your original question... whoops. I say
the rear almost always loses it first. I bet it has to do with the rear
carrying a greater weight load.

--
Phil, Squid-in-Training

Werehatrack said:

Quoted message said:

So there you are, zooming down an Alpine descent with a pair
of brand new identical tires, properly inflated. You dive
into the first turn, your inside pedal up, the pavement
perfect, the road clear, no braking needed in your opinion--

Oops! A bit too fast!

Hope you caught a glimpse of the skid marks.

There won't be any.

Quoted message said:

Please take a moment to explain which tire lost traction
first and why.

Probably the rear, by a small fraction of a second. As soon as it
loses traction, the rider and bike starts to fall toward the pavement;
this increases the angle of the remaining tire to the road surface,
washing it out immediately as well. It really matters little which
one slips first; once one's sliding, the other will lose traction as
well. If you go in too fast to brake without breaking traction,
you're *way* too fast, and you're probably going down.

People who ride incautiously in a hilly area as a result of habits
ingrained after years of living in a very flat place often discover
this feature of curves in dramatic fashion.

Dear Werehatrack,

Why the rear tire?

Carl Fogel

ZeeExSixAre said:

Quoted message said:

With that in mind, does the front tire still dig in instead
of losing traction and flip the rear wheel up into the air?
That is, rear tire loses traction first?

Have you not watched MotoGP? Or at least the crashes from it? It's
invariably a lowside or highside.

I lowsided on campus a few years back on the road bike... there was sand in
a corner, and the damage was light road rash at about 25+mph. It was very
calm and progressive... I was leaned over so far that my body only had about
30 more degrees to fall to reach the ground.

I've highsided my mountain bike in a similar spot, but only because I
steered too fast... I was leaned over at maybe 50 degrees or so, and then
quickly tried to flick back up to vertical. Except it happened really fast,
throwing me high into the air. The landing hurt... so I just try to lowside
now.

My response had nothing to do with your original question... whoops. I say
the rear almost always loses it first. I bet it has to do with the rear
carrying a greater weight load.

Dear Phil,

If you think that you can lure me--me of all people!--into
criticizing a digression, then I have a long and interesting
story to--

Never mind.

Besides, you answered the question, so how can I complain?

But given identical tires, wouldn't the one with the greater
load be less likely to lose traction?

Carl Fogel

Quoted message said:

So there you are, zooming down an Alpine descent with a pair
of brand new identical tires, properly inflated. You dive
into the first turn, your inside pedal up, the pavement
perfect, the road clear, no braking needed in your opinion--

Oops! A bit too fast!

Hope you caught a glimpse of the skid marks.

Please take a moment to explain which tire lost traction
first and why.

If you have time before the bottom of the cliff, please
describe what your other tire did.

The rear one, from a nasty experience on a wet road [1]. Maybe it's
because it can't steer into the turn like the front one?

[1] I managed to save it, but the wheel went a good foot sideways.

In article <[email hidden]>,

Quoted message said:

So there you are, zooming down an Alpine descent with a pair
of brand new identical tires, properly inflated. You dive
into the first turn, your inside pedal up, the pavement
perfect, the road clear, no braking needed in your opinion--

Oops! A bit too fast!

Hope you caught a glimpse of the skid marks.

Please take a moment to explain which tire lost traction
first and why.

Breakout occurs when the friction needed to maintain the turn exceeds that
provided at the contact patch. All other things being equal, the amount
provided at the contact patch is determined by the size of the contact
patch, and the normal force. This force goes down with angle of lean, which
is why leaning too far over results in breakout and why banked turns help
prevent it. Barring unusual topography, the angles of lean for front and
rear should be similar. In a static situation on level ground, more weight
is on the rear, but as the downhill slope gets greater, relatively more is
on the front, and another variable is baggage loading and rider position.
In practice though breakout will often be first initiated at the rear,
because the rider is usually trying to brake, with the resulting weight
transfer effect adding on to the other factors, or perhaps even
inadvertently locking the rear wheel and going into sliding friction mode.

Another factor is any bumps which may result in reduction of contact force
on the way down.

--
TO WHOM IT MAY CONCERN

Please excuse the inconvenience allegedly caused by our son. Send
us the bill for all the damages, and we can settle this to your
satisfaction, without any need for a public record of the incident.

Most Sincerely, George and Bar

<[email hidden]> schreef in bericht
news:[email hidden]...

Quoted message said:

So there you are, zooming down an Alpine descent with a pair
of brand new identical tires, properly inflated. You dive
into the first turn, your inside pedal up, the pavement
perfect, the road clear, no braking needed in your opinion--

Oops! A bit too fast!

Hope you caught a glimpse of the skid marks.

Please take a moment to explain which tire lost traction
first and why.

If you have time before the bottom of the cliff, please
describe what your other tire did.

Thanks,

Carl Fogel

rear tyre, coz you break whilst making a curve and in the stress of the
moment you're using the rear breaks instead of the front ones.

--
Posted by news://news.nb.nu

Carl Fogel said:

Quoted message said:

Descending:

Quoted message said:

Quoted message said:

http://draco.acs.uci.edu/rbfaq/FAQ/9.15.html

Quoted message said:

Quoted message said:

Going over the bars:

Quoted message said:

Quoted message said:

http://draco.acs.uci.edu/rbfaq/FAQ/9.36.html

Quoted message said:

We're all aware of what a wonderful descender you are. If we forget,
I'm sure that you'll remind us.

Quoted message said:

Feel free to change things to a flat paved road with no descent if
it makes you happier.

That makes no difference. Descending is only used to rule out all
sorts of extraneous effects people perceive affecting their cornering.
This all applies to flat roads as well except that pedaling is easily
brought into the effects. If you are pedaling around curves, you're
way below maximum speed so that is a different situation and requires
different skills.

Quoted message said:

Braking was removed to reduce the question to pure cornering.

Well braking is an essential part of cornering as I explained. For
hard cornering, the curve must be approached with excess speed and
that requires brakes. That method is described in the descending
piece.

Quoted message said:

If I were a descender, it would still be a question that you failed
to answer on your first try. Good luck on any subsequent effort.

Quoted message said:

Which tire loses traction first and why? Or did you mean to say
that both tires invariably lose traction simultaneously?

Yes, especially if there is no braking or pedaling involved. I have
had the experience of testing this on a test bed and in real life.

Jobst Brandt
[email hidden]