Avocet Touring Tires

Chris B. wrote:

On Thu, 29 Jul 2004 18:46:54 -0400, Sheldon Brown
wrote:

I pontificated:

hydroplaning is impossible for bicycles

Størker Moe asked:

I don't disbelieve you, but why then do almost all tires for flat-bar
bikes have tread? I've hardly seen any 26" tire (or 28" non-racer bike
tire) with a smooth surface...

In a word: marketing.

It is very counterintuitive to ride on smooth tires. Most people, when
they see slick tires, the first thing that goes through their head is
the thought that they must be very slippery in wet conditions.

People who comment on the slick tires I use usually seem to think that
the tires are worn to the point of total baldness.

I have a pair of completely slick "Specialized Fatboys" on one of my
bikes. The day after I bought them, someone remarked "wow, you must have
ridden a long way on those!" If he'd looked closer, he would have seen the
seam from the mold down the centre of the tire still visible.

--
Benjamin Lewis

A small, but vocal, contingent even argues that tin is superior, but they
are held by most to be the lunatic fringe of Foil Deflector Beanie science.

Benjamin Lewis wrote:

wrote:


Benjamin Lewis wrote:


wrote:


As I indicated before, there are many cases where hydroplaning is a
serious problem, but road bicycles aren't among them. The formula
given was: V(mph) = 10 * sq.rt.[tire pressure(psi)], corresponding to
the usual aviation formula which uses a multiplier of 9 since the
velocity is given in knots rather than mph.% For bicycle road tires the
pressures are usually at least 100 psi, so the speed needs to get up to
about 100 mph before hydroplaning would be likely. But car tires are
usually run at about 30 psi and then hydroplaning can occur at any
speed above about 55 mph. In that case it's a good idea to design the
tire with grooves in the tread that minimize the chance of
hydroplaning. One effect of the grooves is to increase the effective
pressure of the line of tread between the grooves.

But a narrow tire doesn't achieve the same effect? Why do grooves
minimize the chances of hydroplaning, but tires that are the width of
the material between those grooves do not?

A narrow, high-pressure bicycle tire does achieve the same effect;
i.e. it isn't subject to hydroplaning at normal speeds. But there's no
need for any grooves or other tread pattern on the bike tires since they
have sufficient pressure already to avoid the problem.


I'm not disputing that bicycles may be able to hydroplane at extremely high
speeds. I just don't believe you can determine what that speed is by this
formula for airplane tires.

If you have an alternative way of determining what speeds would be safe
from hydroplaning let's hear it.

I imagine this formula has been simplified,
and that it includes a bit of a "safety factor" to cope with this.

Even if true I fail to see what difference it makes. The formula as
given already indicates that bicycles won't hydroplane at speeds of less
than about 100 mph. It really doesn't matter to me if there's a safety
factor and I could really go up to say 150 mph - I have no intention of
ever reaching either speed on my bicycle.

Can you
provide a citation for the derivation of this formula?

Not really interested in working out a derivation. If you are I'd
suggest starting by considering the force required to move the water out
of the way and what's available from the pressure of the tire.

wrote:

Benjamin Lewis wrote:

I'm not disputing that bicycles may be able to hydroplane at extremely
high speeds. I just don't believe you can determine what that speed is
by this formula for airplane tires.

If you have an alternative way of determining what speeds would be safe
from hydroplaning let's hear it.

I imagine this formula has been simplified,
and that it includes a bit of a "safety factor" to cope with this.

Even if true I fail to see what difference it makes. The formula as
given already indicates that bicycles won't hydroplane at speeds of less
than about 100 mph. It really doesn't matter to me if there's a safety
factor and I could really go up to say 150 mph - I have no intention of
ever reaching either speed on my bicycle.

I do not know of another way to determine hydroplaning speeds barring more
experimentation. I agree with you that hydroplaning is not a problem on
bicycles; I think it's even *less* of a problem than is indicated by this
formula. I believe determining hydroplaning speeds would be a purely
academic exercise.

Can you provide a citation for the derivation of this formula?

Not really interested in working out a derivation. If you are I'd
suggest starting by considering the force required to move the water out
of the way and what's available from the pressure of the tire.

I was asking for a citation, not a theoretical derivation. Where did you
get this formula from? Did they publish the data with which they derived
it?

--
Benjamin Lewis

A small, but vocal, contingent even argues that tin is superior, but they
are held by most to be the lunatic fringe of Foil Deflector Beanie science.

Sheldon Brown wrote:

...
Hydroplaning is an issue for cars and motorcycles (though a rare one: in
my 44 years of driving, I've only experienced hydroplaning once.)....

This proves that Mr. Brown is not sufficiently crazy with the use of the
"loud pedal".

--
Tom Sherman – Quad City Area

Mike DeMicco wrote in message ...
In article ,
Sheldon Brown wrote:

I pontificated:

hydroplaning is impossible for bicycles

Størker Moe asked:

I don't disbelieve you, but why then do almost all tires for flat-bar
bikes have tread? I've hardly seen any 26" tire (or 28" non-racer bike
tire) with a smooth surface...

In a word: marketing.


No, it's because flat bar bikes are mountain bikes or hybrids, meant to
be ridden on dirt. Slicks work poorly on dirt but great on pavement.

This is not quite true either. Smooth tread (please, let's not
further the misconceptions by calling them "slicks") works fine on
dirt. "In" dirt is another thing. I ride on a variety of dirt
conditions with my smooth treaded road bike. The only place it is a
deficit is on wet dirt. Then, tread patterns help only if they can
dig in a bit.

Robin Hubert

Trevor Jeffrey wrote:

...In order for a bald tyre to function in the wet, extreme inflation
pressure is required to attempt to match the penetrative qualities of a
treaded tyre with its associated regions of high pressure. The extreme
inflation pressure shortens the tyre contact patch to a length where
insufficient lateral stability of the tyre is available resulting in
skittish behaviour in the dry and sideslip in the wet though corners. The
above is assuming a nominal wheel diameter of 27", riders of 48" wheels and
above may find adequacy in bald, hard and narrow tyres....

I find the wet pavement traction of 44-406 Avocet Fasgrip Freestyle
"slick" tires to be quite adequate - much better than that of the 37-406
Primo Comets (with "herringbone" tread) that they replaced. Both types
of tires were inflated to about 90 psi.

--
Tom Sherman – Quad City Area

Chris B. wrote:

On Thu, 29 Jul 2004 20:46:27 +0100, "Trevor Jeffrey"
wrote:


Sheldon Brown wrote in message ...

Hydroplaning is an issue for cars and motorcycles (though a rare one: in
my 44 years of driving, I've only experienced hydroplaning once.)

However, hydroplaning is impossible for bicycles, so this is a non-issue.


Aquaplaning is the term, and certainly has happened to me riding a bicycle.
Speed of about 40mph downhill, sheet of water over the road, bucketing it
down. Apply brakes to slow to negotiate parked car, bike drifts towards
gutter maintaining speed, look down, front wheel locked so release brakes.
Balance was retained with slow response to steering efforts. Rare but
possible.


Was the hub hanging from the top spokes at the time?

Hydroplaning can be prevented by riding a frame that is stiff, yet
compliant.

--
Tom Sherman – Quad City Area

I wrote:

Hydroplaning is an issue for cars and motorcycles (though a rare one: in
my 44 years of driving, I've only experienced hydroplaning once.)

However, hydroplaning is impossible for bicycles, so this is a non-issue.

Trevor Jeffrey wrote:

Aquaplaning is the term,

Aquaplaning is the term in British usage, but I'm an American, so I
commonly use the American term "hydroplaning."

I'll grant that "aquaplaning" is more linguistically pure, since it is
compounded of two Latin roots, rather than Latin mixed with Greek as
with "hydroplaning" but "hydroplaning" is the more standardd usage in
American English.

I'm getting tyred of this sort of condescending carping from the other
side of the Pond.

Since the automobile/motorcar was invented after American independence,
practically every technical term relating to motor vehicles is different
depending on which side of the Atlantic you live on. This doesn't mean
that one usage is "right" and that the other is "wrong." Deal with it.

Sheldon "Bilingual In English" Brown
+---------------------------------------------------+
| Two countries, divided by a common language. |
| -- George Bernard Shaw |
+---------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Tom Sherman wrote:
Chris B. wrote:

On Thu, 29 Jul 2004 20:46:27 +0100, "Trevor Jeffrey"
wrote:


Sheldon Brown wrote in message ...

Hydroplaning is an issue for cars and motorcycles (though a rare
one: in
my 44 years of driving, I've only experienced hydroplaning once.)

However, hydroplaning is impossible for bicycles, so this is a
non-issue.


Aquaplaning is the term, and certainly has happened to me riding a
bicycle.
Speed of about 40mph downhill, sheet of water over the road,
bucketing it
down. Apply brakes to slow to negotiate parked car, bike drifts
towards
gutter maintaining speed, look down, front wheel locked so release
brakes.
Balance was retained with slow response to steering efforts. Rare but
possible.



Was the hub hanging from the top spokes at the time?


Hydroplaning can be prevented by riding a frame that is stiff, yet
compliant.


I've been following this intriguing thread the past day or so. Amazing
stuff, what you people get up to.

Not even the pro riders can make their bikes aquaplane. And I thought
*they* were fast.

Loss of grip when cornering or braking is one thing. Increase of slip
angle is what happens in the wet, when cornering. But you people must be
a completely different class of riders to be able to go so quickly that
you can cause genuine aquaplaning, and then live to tell the story.

For my own part, I have no problem keeping an acceptable level of grip
on my normal road bike doing 60 km/h downhill in the rain, with
treadless tyres. A bit of common sense is needed to keep skull intact,
is all.

Maybe the solution is for you guys just to slow down a bit when the grip
is bad?

/Robert

Chris B. wrote in message ...
Was the hub hanging from the top spokes at the time?
No it was attempting a tango with the headset whilst striking up a tune with
the spokes.
TJ