Which Tire Loses Traction First?

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

wrote:
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.

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.

wrote:
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.

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 writes:

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.

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.

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.

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

Carl Fogel writes:

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.

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.

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.

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

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.

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

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.

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

Wrote:
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 commenc
skidding simultaneously on the neutral handling bike.

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

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

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

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

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

On the front suspended SWB recumbent the rear loses traction first

--
meb

Wrote:
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 commenc
skidding simultaneously on the neutral handling bike.

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

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

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

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

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

On the front suspended SWB recumbent the rear loses traction first

--
meb

On Sat, 04 Sep 2004 04:19:46 GMT,
wrote:

Carl Fogel writes:

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.

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.

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.

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


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