Tire pressure and bad bike shop advice.



Hiya:
So, when I picked up my new bike at the LBS, I asked about how low I
could/should go on tire inflation. Background: It's a loaded touring
bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
less than 150 lb and my food-oriented usual group ride group has an
instinct for finding really bad roads (Harmony Grove Road, 30th St.,
etc. for those who've experience with San Diego and the joys of riding
"deferred maintenance.") And I won't usuallly be riding with a full
load -- I just wanted a drop bar pickup truck that could take the
commute and the grocery store run.
The answer -- "Don't go under 100 or you'll get pinch flats." This
somewhat shocked me, because I've met a few (really slender) brevet
riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
in getting the big wheel if you can''t get some decent cushioning out
of it?

Robert Leone [email protected]
 
[email protected] wrote:
> Hiya:
> So, when I picked up my new bike at the LBS, I asked about how low I
> could/should go on tire inflation. Background: It's a loaded touring
> bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
> less than 150 lb and my food-oriented usual group ride group has an
> instinct for finding really bad roads (Harmony Grove Road, 30th St.,
> etc. for those who've experience with San Diego and the joys of riding
> "deferred maintenance.") And I won't usuallly be riding with a full
> load -- I just wanted a drop bar pickup truck that could take the
> commute and the grocery store run.
> The answer -- "Don't go under 100 or you'll get pinch flats." This
> somewhat shocked me, because I've met a few (really slender) brevet
> riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
> in getting the big wheel if you can''t get some decent cushioning out
> of it?
>
> Robert Leone [email protected]
>

I did a loaded tour on 700x35s' and kept them between 85 and 90. They
were rated for 85. I didn't have one flat in 1200 miles.

Ken
--
You never have the wind with you - either it is against you or you're
having a good day. ~Daniel Behrman, The Man Who Loved Bicycles

Homepage: http://www.bikesandmoreonline.com/
 
[email protected] wrote:
> Hiya:
> So, when I picked up my new bike at the LBS, I asked about how low I
> could/should go on tire inflation. Background: It's a loaded touring
> bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
> less than 150 lb and my food-oriented usual group ride group has an
> instinct for finding really bad roads (Harmony Grove Road, 30th St.,
> etc. for those who've experience with San Diego and the joys of riding
> "deferred maintenance.") And I won't usuallly be riding with a full
> load -- I just wanted a drop bar pickup truck that could take the
> commute and the grocery store run.
> The answer -- "Don't go under 100 or you'll get pinch flats." This
> somewhat shocked me, because I've met a few (really slender) brevet
> riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
> in getting the big wheel if you can''t get some decent cushioning out
> of it?
>
> Robert Leone [email protected]
>

Uh, ride around the holes. That is one of the advantages of having a
bike and only 2 wheels to worry about instead of a car where you just
know you are going to hit one on the left or right.
Bill Baka
 
"Bill Baka" <[email protected]> wrote in message
news:[email protected]...
> [email protected] wrote:
>> Hiya:
>> So, when I picked up my new bike at the LBS, I asked about how low I
>> could/should go on tire inflation. Background: It's a loaded touring
>> bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
>> less than 150 lb and my food-oriented usual group ride group has an
>> instinct for finding really bad roads (Harmony Grove Road, 30th St.,
>> etc. for those who've experience with San Diego and the joys of riding
>> "deferred maintenance.") And I won't usuallly be riding with a full
>> load -- I just wanted a drop bar pickup truck that could take the
>> commute and the grocery store run.
>> The answer -- "Don't go under 100 or you'll get pinch flats." This
>> somewhat shocked me, because I've met a few (really slender) brevet
>> riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
>> in getting the big wheel if you can''t get some decent cushioning out
>> of it?
>>
>> Robert Leone [email protected]
>>

> Uh, ride around the holes. That is one of the advantages of having a bike
> and only 2 wheels to worry about instead of a car where you just know you
> are going to hit one on the left or right.
> Bill Baka


I put 2500 km on my 700X32's last year with 75 rear/70 front. They are rated
at 85psi Only flat I got was when I picked up a piece of wire - no pinch
flats. I weigh 200 lbs

Mike
 
Weather Guy wrote:
> "Bill Baka" <[email protected]> wrote in message
> news:[email protected]...
>
>>[email protected] wrote:
>>
>>>Hiya:
>>> So, when I picked up my new bike at the LBS, I asked about how low I
>>>could/should go on tire inflation. Background: It's a loaded touring
>>>bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
>>>less than 150 lb and my food-oriented usual group ride group has an
>>>instinct for finding really bad roads (Harmony Grove Road, 30th St.,
>>>etc. for those who've experience with San Diego and the joys of riding
>>>"deferred maintenance.") And I won't usuallly be riding with a full
>>>load -- I just wanted a drop bar pickup truck that could take the
>>>commute and the grocery store run.
>>> The answer -- "Don't go under 100 or you'll get pinch flats." This
>>>somewhat shocked me, because I've met a few (really slender) brevet
>>>riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
>>>in getting the big wheel if you can''t get some decent cushioning out
>>>of it?
>>>
>>>Robert Leone [email protected]
>>>

>>
>>Uh, ride around the holes. That is one of the advantages of having a bike
>>and only 2 wheels to worry about instead of a car where you just know you
>>are going to hit one on the left or right.
>>Bill Baka

>
>
> I put 2500 km on my 700X32's last year with 75 rear/70 front. They are rated
> at 85psi Only flat I got was when I picked up a piece of wire - no pinch
> flats. I weigh 200 lbs
>
> Mike
>
>

Aren't you putting in a lot of extra work pushing a half flat tire and
defeating the road bike skinny tire thing?
I run my mountain bikes at 65 psi and I go from 170 (fat) in the winter
to 140 (skinny) in the summer.
Curious.
Bill
 
> So, when I picked up my new bike at the LBS, I asked about how low I
> could/should go on tire inflation. Background: It's a loaded touring
> bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
> less than 150 lb and my food-oriented usual group ride group has an
> instinct for finding really bad roads (Harmony Grove Road, 30th St.,
> etc. for those who've experience with San Diego and the joys of riding
> "deferred maintenance.") And I won't usuallly be riding with a full
> load -- I just wanted a drop bar pickup truck that could take the
> commute and the grocery store run.
> The answer -- "Don't go under 100 or you'll get pinch flats." This
> somewhat shocked me, because I've met a few (really slender) brevet
> riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
> in getting the big wheel if you can''t get some decent cushioning out
> of it?


100psi might be a bit higher than needed for a 32c tire, but if the roads
are truly that bad, and the shop knows that, it might not be totally
unrealistic. As for comfort, simply having a 32c tire to begin with helps
greatly in that regard.

Those running 90 to 100psi in a 23c tire (and not getting flats) have an
angel on their shoulder. Unfortunately, there seems to be a shortage of such
angels to go around.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
 
[email protected] wrote:
> Hiya:
> So, when I picked up my new bike at the LBS, I asked about how low I
> could/should go on tire inflation. Background: It's a loaded touring
> bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
> less than 150 lb and my food-oriented usual group ride group has an
> instinct for finding really bad roads (Harmony Grove Road, 30th St.,
> etc. for those who've experience with San Diego and the joys of riding
> "deferred maintenance.") And I won't usuallly be riding with a full
> load -- I just wanted a drop bar pickup truck that could take the
> commute and the grocery store run.
> The answer -- "Don't go under 100 or you'll get pinch flats." This
> somewhat shocked me, because I've met a few (really slender) brevet
> riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
> in getting the big wheel if you can''t get some decent cushioning out
> of it?
>


Find a new LBS.

Sheldon brown recommends 75psi for 32mm wide tires carrying 100 lbs of
load per tire (200lbs for the whole bike). Take a look at:

http://sheldonbrown.com/tires.html#pressure

Personally, I ride 700x32 tires commuting on bad roads in the city with
a fiar load. I used to inflate my tires to 90psi, but these days I
won't go above 80psi, as they are so much comfier that way. When I
finally get around to top up the pressure, they are usaually around 65
psi, and I don't get pinch flats - my flats are caused by sharp pieces
of metal - staples, nails, cotter pins, etc, etc.

Later,
Mark Muller
 
On Sun, 12 Mar 2006 22:27:39 +0000, Mike Jacoubowsky wrote:

>> So, when I picked up my new bike at the LBS, I asked about how low I
>> could/should go on tire inflation. Background: It's a loaded touring
>> bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
>> less than 150 lb and my food-oriented usual group ride group has an
>> instinct for finding really bad roads (Harmony Grove Road, 30th St.,
>> etc. for those who've experience with San Diego and the joys of riding
>> "deferred maintenance.") And I won't usuallly be riding with a full
>> load -- I just wanted a drop bar pickup truck that could take the
>> commute and the grocery store run.
>> The answer -- "Don't go under 100 or you'll get pinch flats." This
>> somewhat shocked me, because I've met a few (really slender) brevet
>> riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
>> in getting the big wheel if you can''t get some decent cushioning out
>> of it?

>
> 100psi might be a bit higher than needed for a 32c tire, but if the roads
> are truly that bad, and the shop knows that, it might not be totally
> unrealistic. As for comfort, simply having a 32c tire to begin with helps
> greatly in that regard.
>
> Those running 90 to 100psi in a 23c tire (and not getting flats) have an
> angel on their shoulder. Unfortunately, there seems to be a shortage of such
> angels to go around.


Lately I've been riding with 7 bar (101psi) in my front tire (23mm).
I'm about 170#, not particularly careful, and I ride some pretty rough
roads. I never get pinch flats.

I've been told by two different pro team mechanics that they also use 7-8
bar for most riders. Pros may be lighter on average but ride faster --
so they probably hit harder, plus anyone who has raced knows hitting
potholes and other hazards is inevitable when boxed in by the peloton.

If so many of us can ride successfully at ~100psi with 23mm tires, then
surely you can use much lower pressures with 32mm, especially if you're
lightly loaded.

Matt O.
 
[email protected] wrote:
> [email protected] wrote:
>
>>Hiya:
>> So, when I picked up my new bike at the LBS, I asked about how low I
>>could/should go on tire inflation. Background: It's a loaded touring
>>bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
>>less than 150 lb and my food-oriented usual group ride group has an
>>instinct for finding really bad roads (Harmony Grove Road, 30th St.,
>>etc. for those who've experience with San Diego and the joys of riding
>>"deferred maintenance.") And I won't usuallly be riding with a full
>>load -- I just wanted a drop bar pickup truck that could take the
>>commute and the grocery store run.
>> The answer -- "Don't go under 100 or you'll get pinch flats." This
>>somewhat shocked me, because I've met a few (really slender) brevet
>>riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
>>in getting the big wheel if you can''t get some decent cushioning out
>>of it?
>>

>
>
> Find a new LBS.
>
> Sheldon brown recommends 75psi for 32mm wide tires carrying 100 lbs of
> load per tire (200lbs for the whole bike). Take a look at:
>
> http://sheldonbrown.com/tires.html#pressure
>
> Personally, I ride 700x32 tires commuting on bad roads in the city with
> a fiar load. I used to inflate my tires to 90psi, but these days I
> won't go above 80psi, as they are so much comfier that way. When I
> finally get around to top up the pressure, they are usaually around 65
> psi, and I don't get pinch flats - my flats are caused by sharp pieces
> of metal - staples, nails, cotter pins, etc, etc.
>
> Later,
> Mark Muller
>

No argument about the 100 lbs per tire but most of your weight is on the
seat post so it is more like 150/50. And what about sitting up and
riding no hands? Most of us probably do it, safe or not, I admit to it
after about ten miles just to relax my wrists.
Better safe than walking.
Bill
 
> Lately I've been riding with 7 bar (101psi) in my front tire (23mm).
> I'm about 170#, not particularly careful, and I ride some pretty rough
> roads. I never get pinch flats.


I'm not convinced that pinch flats are the only type of flat reduced by
higher pressures. I don't understand the mechanism, but it seems that my
customers running lower pressures get more flats from objects that become
embedded in their tires as well.

> I've been told by two different pro team mechanics that they also use 7-8
> bar for most riders. Pros may be lighter on average but ride faster --
> so they probably hit harder, plus anyone who has raced knows hitting
> potholes and other hazards is inevitable when boxed in by the peloton.


Speed is a key element, along with riding in a pack and not being near the
front. The higher the speed, the more force upon the tire when you hit a
pothole (and the more likely you'll bottom out). Ironically, at higher
speeds, the impact often feels less severe, perhaps because you have more
forward momentum. Riding in a pack is an issue as those toward the back
don't see what's on the road in front of them, and they're also likely
riding "on the rivet" and not as able to take evasive maneuvers when
something is spotted.

> If so many of us can ride successfully at ~100psi with 23mm tires, then
> surely you can use much lower pressures with 32mm, especially if you're
> lightly loaded.


The original poster talked about his bike both set up for loaded touring as
well as lightly loaded. A loaded touring bike can be pretty deadly for pinch
flats, because you can't easily lift the wheels (or jump the bike) over
whatever shows up in front of you. But all things being equal, a tire with
greater air volume will allow for lower tire pressures.

> Matt O.


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


"Matt O'Toole" <[email protected]> wrote in message
news:p[email protected]...
> On Sun, 12 Mar 2006 22:27:39 +0000, Mike Jacoubowsky wrote:
>
>>> So, when I picked up my new bike at the LBS, I asked about how low I
>>> could/should go on tire inflation. Background: It's a loaded touring
>>> bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
>>> less than 150 lb and my food-oriented usual group ride group has an
>>> instinct for finding really bad roads (Harmony Grove Road, 30th St.,
>>> etc. for those who've experience with San Diego and the joys of riding
>>> "deferred maintenance.") And I won't usuallly be riding with a full
>>> load -- I just wanted a drop bar pickup truck that could take the
>>> commute and the grocery store run.
>>> The answer -- "Don't go under 100 or you'll get pinch flats." This
>>> somewhat shocked me, because I've met a few (really slender) brevet
>>> riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
>>> in getting the big wheel if you can''t get some decent cushioning out
>>> of it?

>>
>> 100psi might be a bit higher than needed for a 32c tire, but if the roads
>> are truly that bad, and the shop knows that, it might not be totally
>> unrealistic. As for comfort, simply having a 32c tire to begin with helps
>> greatly in that regard.
>>
>> Those running 90 to 100psi in a 23c tire (and not getting flats) have an
>> angel on their shoulder. Unfortunately, there seems to be a shortage of
>> such
>> angels to go around.

>
> Lately I've been riding with 7 bar (101psi) in my front tire (23mm).
> I'm about 170#, not particularly careful, and I ride some pretty rough
> roads. I never get pinch flats.
>
> I've been told by two different pro team mechanics that they also use 7-8
> bar for most riders. Pros may be lighter on average but ride faster --
> so they probably hit harder, plus anyone who has raced knows hitting
> potholes and other hazards is inevitable when boxed in by the peloton.
>
> If so many of us can ride successfully at ~100psi with 23mm tires, then
> surely you can use much lower pressures with 32mm, especially if you're
> lightly loaded.
>
> Matt O.
 
Mike Jacoubowsky wrote:
Snipping original poster (me):

> 100psi might be a bit higher than needed for a 32c tire, but if the roads
> are truly that bad, and the shop knows that, it might not be totally
> unrealistic.


Most of the time when I've got one of those "measure in seconds of air
time, not inches of depth" potholes in front of me, the Graffittied
Jersey Barricade to the right and the Garbage Truck of Doom to the left
I have enough presence of mind to stand up and shift body weight aft,
then fore as I traverse the rut. As a rule the roads aren't that bad,
but we do have a few places with actual imitation cobblestones,
senselessly deep cross-grooves, and some neighborhoods where frankly,
the streets aren't in good shape (doesn't everyone have some of those
in their area?). Also, the contractor who grooves the verges of streets
before chip-sealing or complete asphault-spreading seems to be running
two or three months ahead of the crews that lay the new road surfaces.
Since my usual riding group tends be cyclo-tourism oriented, if there's
an interesting bad road, we're probably a bit more likely than the
race-oriented ride groups to find it.

As for comfort, simply having a 32c tire to begin with helps
> greatly in that regard.
>

I've seen a few diverging opinions that pressure's a greater
determinant than tire size. This bike is my first road bike, so I've
litte experience with the ways of skinny tires. My previous experience
in something approaching 700x32c is my mom's Schwinn Suburban
step-through with fenders, steel rimmed wheels and 27 inch by 1 1/4
tires. And Shimano Positron drivetrain! It's not exactly a "fast" bike,
either.

> Those running 90 to 100psi in a 23c tire (and not getting flats) have an
> angel on their shoulder. Unfortunately, there seems to be a shortage of such
> angels to go around.


Most of those brevet riders were running 700x23c tires at 110 to 120
psi -- the ones who said their favorite pressure was 100 or less also
looked like they weighed 120 lb or less.

Thanks for writing back!

> --Mike-- Chain Reaction Bicycles
> www.ChainReactionBicycles.com
 
<[email protected]> wrote ...
> Hiya:
> So, when I picked up my new bike at the LBS, I asked about how low I
> could/should go on tire inflation. Background: It's a loaded touring
> bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
> less than 150 lb and my food-oriented usual group ride group has an
> instinct for finding really bad roads (Harmony Grove Road, 30th St.,
> etc. for those who've experience with San Diego and the joys of riding
> "deferred maintenance.") And I won't usuallly be riding with a full
> load -- I just wanted a drop bar pickup truck that could take the
> commute and the grocery store run.
> The answer -- "Don't go under 100 or you'll get pinch flats." This
> somewhat shocked me, because I've met a few (really slender) brevet
> riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
> in getting the big wheel if you can''t get some decent cushioning out
> of it?
>
> Robert Leone
>


A long time ago I was told by a bike shop to keep my tires at a high enough
pressure to keep the sidewalls from bulging at the tire/ground contact point
when I was sitting on the pint. Seems like a sensible yardstick to me.

FWIW, I run all my bike tires at or slightly above the maximum pressure
stamped on the sidewall, the tires run smoothly and I very seldom get flats.
--
mark
 
Mike Jacoubowsky wrote:
> The original poster talked about his bike both set up for loaded touring as
> well as lightly loaded. A loaded touring bike can be pretty deadly for pinch
> flats, because you can't easily lift the wheels (or jump the bike) over
> whatever shows up in front of you.


Let's not forget the things that we *don't* see.

I'm on the big side (hovering around 210lbs most of the time) riding
23mm tires which I keep around 120psi.

There is this one pavement transition on my commute that for which I I
always get off the seat since it is a bit sharp. It is on a downhill
run, so I usually hit it about 25mph.

A couple of months ago, I was running late in the morning and didn't
have time to check tire pressures. Both felt a little low, but I wasn't
worried! A late morning turned into a late evening and I was caught out
after dark. No worries, I have lights!

But when I got to that transition, I was moving a bit too fast to see
it clearly and I hit it while seated. The low tire and my seated weight
resulted in my rear tire receiving a nice pinch flat. Of course, then I
was stuck changing a flat in the dark. Fortunately, it wasn't
raining....

-Buck
 
mark wrote:
> <[email protected]> wrote ...
>
>>Hiya:
>> So, when I picked up my new bike at the LBS, I asked about how low I
>>could/should go on tire inflation. Background: It's a loaded touring
>>bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
>>less than 150 lb and my food-oriented usual group ride group has an
>>instinct for finding really bad roads (Harmony Grove Road, 30th St.,
>>etc. for those who've experience with San Diego and the joys of riding
>>"deferred maintenance.") And I won't usuallly be riding with a full
>>load -- I just wanted a drop bar pickup truck that could take the
>>commute and the grocery store run.
>> The answer -- "Don't go under 100 or you'll get pinch flats." This
>>somewhat shocked me, because I've met a few (really slender) brevet
>>riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
>>in getting the big wheel if you can''t get some decent cushioning out
>>of it?
>>
>>Robert Leone
>>

>
>
> A long time ago I was told by a bike shop to keep my tires at a high enough
> pressure to keep the sidewalls from bulging at the tire/ground contact point
> when I was sitting on the pint. Seems like a sensible yardstick to me.
>
> FWIW, I run all my bike tires at or slightly above the maximum pressure
> stamped on the sidewall, the tires run smoothly and I very seldom get flats.


The last time I tried to run a tire over the maximum, about 130 PSI, I
got a very attention getting explosion and walk home, then had to buy a
new tire and tube. Ever have a big firecracker go off just in front of
your face? It was loud. Now for the big admission, I bought the tire at
Wal-mart and it was a made in China type, so fair warning about saving a
few bucks on tires, not worth it.
Bill Baka
 
An anonymous poster wrote:

> A long time ago I was told by a bike shop to keep my tires at a high enough
> pressure to keep the sidewalls from bulging at the tire/ground contact point
> when I was sitting on the pint. Seems like a sensible yardstick to me.


Not to me. The tire is _supposed- to bulge at the tire/ground contact
point. That is the purpose of pneumatic tires.

> FWIW, I run all my bike tires at or slightly above the maximum pressure
> stamped on the sidewall, the tires run smoothly and I very seldom get flats.


The number marked on the sidewall are generally of zero value as a
reference, for reasons that I explain at:

http://sheldonbrown.com/tires.html#pressure

Bill Baka wrote:

> No argument about the 100 lbs per tire but most of your weight is on
> the seat post so it is more like 150/50.


Typical upright style bikes have about a 55/45 weight distribution, so
it would be more like 110/90.

> And what about sitting up and riding no hands? Most of us probably do
> it, safe or not


You do this on rough roads that put you at risk for pinch flats? You're
braver than I.

Sheldon "Depends On The Surface" Brown
+---------------------------------------------------------+
| In skating over thin ice, our safety is in our speed. |
| --R.W. Emerson |
+---------------------------------------------------------+
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
 
[email protected] wrote:
> Hiya:
> So, when I picked up my new bike at the LBS, I asked about how low I
> could/should go on tire inflation. Background: It's a loaded touring
> bike with 700x32c tires, max pressure 110 psi, I weigh only SLIGHTLY
> less than 150 lb and my food-oriented usual group ride group has an
> instinct for finding really bad roads (Harmony Grove Road, 30th St.,
> etc. for those who've experience with San Diego and the joys of riding
> "deferred maintenance.") And I won't usuallly be riding with a full
> load -- I just wanted a drop bar pickup truck that could take the
> commute and the grocery store run.
> The answer -- "Don't go under 100 or you'll get pinch flats." This
> somewhat shocked me, because I've met a few (really slender) brevet
> riders who put 90 to 100 psi in 700x23c tires. I mean, what's the point
> in getting the big wheel if you can''t get some decent cushioning out
> of it?
>
> Robert Leone [email protected]
>


I'm presently over 210 lb running no less than 100 psi on a 23C and have
had no pinch flats in a couple of thousand miles since starting to top
off my tires before every ride. I'd consider 100 to be my minimum
pressure and don't vary it, unless it is a little bit over.
 
Sheldon Brown wrote:
> An anonymous poster wrote:
>
>> A long time ago I was told by a bike shop to keep my tires at a high
>> enough pressure to keep the sidewalls from bulging at the tire/ground
>> contact point when I was sitting on the pint. Seems like a sensible
>> yardstick to me.

>
>
> Not to me. The tire is _supposed- to bulge at the tire/ground contact
> point. That is the purpose of pneumatic tires.
>
>> FWIW, I run all my bike tires at or slightly above the maximum
>> pressure stamped on the sidewall, the tires run smoothly and I very
>> seldom get flats.

>
>
> The number marked on the sidewall are generally of zero value as a
> reference, for reasons that I explain at:
>
> http://sheldonbrown.com/tires.html#pressure
>
> Bill Baka wrote:
>
> > No argument about the 100 lbs per tire but most of your weight is on
> > the seat post so it is more like 150/50.

>
> Typical upright style bikes have about a 55/45 weight distribution, so
> it would be more like 110/90.


Aero position? I ride more upright so maybe a bit different. I go for
exercise and not bragging rights on speed, mainly because a long stretch
of aero gives me, literally, a pain in the neck.
>
> > And what about sitting up and riding no hands? Most of us probably do
> > it, safe or not

>
> You do this on rough roads that put you at risk for pinch flats? You're
> braver than I.
>
> Sheldon "Depends On The Surface" Brown


Depends on surface is right, but I have done it on gravel roads, so my
fear factor is probably out of calibration.
Bill Baka
> +---------------------------------------------------------+
> | In skating over thin ice, our safety is in our speed. |
> | --R.W. Emerson |
> +---------------------------------------------------------+
> 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
>
 
Bill Baka wrote:

> Aero position? I ride more upright so maybe a bit different. I go for
> exercise and not bragging rights on speed, mainly because a long stretch
> of aero gives me, literally, a pain in the neck.


A lot of that pain results from road shock/vibration that you can't damp
out with your elbows when you're riding on an aerobar.

Running a wider, softer front tire will help with this.

Sheldon "Pneumatic" Brown
+--------------------------------------------------------------+
| When I think back on all the **** I learned in high school |
| It's a wonder I can think at all |
| And though my lack of education hasn't hurt me none |
| I can read the writing on the wall --Paul Simon |
+--------------------------------------------------------------+
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
 
On Mon, 13 Mar 2006 21:10:40 +0000, Bill Baka wrote:

> Sheldon Brown wrote:


>> An anonymous poster wrote:


>> > And what about sitting up and riding no hands? Most of us probably do
>> > it, safe or not


>> You do this on rough roads that put you at risk for pinch flats? You're
>> braver than I.


>> Sheldon "Depends On The Surface" Brown


> Depends on surface is right, but I have done it on gravel roads, so my
> fear factor is probably out of calibration.


With a little speed, a bike will track straight even if the road is bumpy.

I ride tens of miles no-hands to rest my lower back, both on road and off
-- particularly on rail-trails.

Matt O.
 
"Sheldon Brown" wrote ...
> An anonymous poster wrote:
>
>> A long time ago I was told by a bike shop to keep my tires at a high
>> enough pressure to keep the sidewalls from bulging at the tire/ground
>> contact point when I was sitting on the pint. Seems like a sensible
>> yardstick to me.

>
> Not to me. The tire is _supposed- to bulge at the tire/ground contact
> point. That is the purpose of pneumatic tires.
>
>> FWIW, I run all my bike tires at or slightly above the maximum pressure
>> stamped on the sidewall, the tires run smoothly and I very seldom get
>> flats.

>
> The number marked on the sidewall are generally of zero value as a
> reference, for reasons that I explain at:
>
> http://sheldonbrown.com/tires.html#pressure
>

I would expect the tire to bulge when absorbing surface irregularities, but
when I'm sitting on the bike on a smooth surface I would not expect to see a
noticeable bulge.
--
mark
 

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