Which Tire Loses Traction First?

Wrote:
On Sat, 4 Sep 2004 14:51:55 +1000, meb
wrote:


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 commence
skidding simultaneously on the neutral handling bike.

One the rear suspended recumbent the rear loses traction firs
because
there are only two chainstays supporting the high rear bias weight
the
chainstays do not provide sufficient torsional rigidity in a har
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 bia
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 s
(4:2, not 5:1).

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

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

If you are decelling in a corner due braking you are shifting weigh
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

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

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

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

If you are decelling in a corner due braking you are shifting weigh
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, slic
tires, no frame suspension and frames that handle the side loads.
Since the rear breaks first, there must be another reason on that typ
bike

--
meb

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

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

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

If you are decelling in a corner due braking you are shifting weigh
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, slic
tires, no frame suspension and frames that handle the side loads.
Since the rear breaks first, there must be another reason on that typ
bike

--
meb

On Fri, 03 Sep 2004 21:31:43 -0600, 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.

There won't be any.

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.

On Fri, 03 Sep 2004 21:31:43 -0600, 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.

There won't be any.

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.

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

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

On Sat, 04 Sep 2004 05:58:23 GMT, Werehatrack
wrote:

On Fri, 03 Sep 2004 21:31:43 -0600, 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.

There won't be any.

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

On Sat, 04 Sep 2004 05:58:23 GMT, Werehatrack
wrote:

On Fri, 03 Sep 2004 21:31:43 -0600, 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.

There won't be any.

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

On Sat, 04 Sep 2004 06:36:18 GMT, "ZeeExSixAre"
wrote:

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