tire pressure with 700x42 tires

[Mark Boyd]

I checked my tire pressure today. I rode my loaded bike home two days
ago and, although the front tire felt a bit soft when I tested it with
my thumb, it still handled OK on a variety of road surfaces so I
didn't worry about it. Today I found that both front and rear tires
were down to nbvear 30 psi. No wonder it was comfortable even on quite
rough. broken, pavement!

I've usually considered 50 psi as the point where I started feeling
deterioration in my loaded touring bikes handling using 700x35 tires.
With 700x42 tires, that point is now well below 40 psi. That makes for
a really comfortable ride!

             Mark

[Mijo]

I am riding 700X42C
Less than 60 PSI on the rear tire is really a drag. I prefer to have the rear tire on 60 PSI, and the front on 50-60 PSI. The ride is a little bumpy, but, peddaling is much easier. Reaching 30 KM/hr with no effort.
As an added bonus, inflating your tire to 60 PSI would decrease the probability of having flats. I checked the tube, and it could hold upto 70 PSI.
Thanks

[Mark Boyd]

How much do you weigh? I weigh about 165 lbs and my touring bike
weighs about 35 pounds. I keep the tire pressure at about 50psi when
I'm doing loaded touring and my bike weight, with rider, is over 250
lbs.
Mark

[LostInTheTrees]

Interesting. I have 700x50 Schwalbe Big Apples and I run about 40 pounds with 260 or so worth of bike and rider. I see no significant deflection of the tires and notice no drag.

-Bob

Tucson AZ - Eugene OR

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[Harley k]

I've always ran on Continentals touring; 700x 35 to 42. I run them at 65-70 psi; BUT my brooks flyer has springs & I always use a seat post that is sprung. (spring) I'm not changing!  harley

Sit and get healthy; ride a bike
 
        

 

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Subject: Re: [touring] tire pressure with 700x42 tires
From: lostint...@rjcarlson.com
Date: Mon, 5 May 2014 10:12:36 -0700
CC: bicycle...@googlegroups.com; mark...@gmail.com
To: maje...@gmail.com

Interesting. I have 700x50 Schwalbe Big Apples and I run about 40 pounds with 260 or so worth of bike and rider. I see no significant deflection of the tires and notice no drag.

-Bob

Tucson AZ - Eugene OR

On May 2, 2014, at 14:45 , Mijo <maje...@gmail.com> wrote:

I am riding 700X42C
Less than 60 PSI on the rear tire is really a drag. I prefer to have the rear tire on 60 PSI, and the front on 50-60 PSI. The ride is a little bumpy, but, peddaling is much easier. Reaching 30 KM/hr with no effort.
As an added bonus, inflating your tire to 60 PSI would decrease the probability of having flats. I checked the tube, and it could hold upto 70 PSI.
Thanks

On Friday, April 13, 2012 2:34:16 AM UTC+3, Mark Boyd wrote:

I checked my tire pressure today. I rode my loaded bike home two days
ago and, although the front tire felt a bit soft when I tested it with
my thumb, it still handled OK on a variety of road surfaces so I
didn't worry about  it. Today I found that both front and rear tires
were down to nbvear 30 psi. No wonder it was comfortable even on quite

rough. broken, pavement!I've usually considered 50 psi as the point where I started feeling

deterioration in my loaded touring bikes handling using 700x35 tires.
With 700x42 tires, that point is now well below 40 psi. That makes for
a really comfortable ride!
             Mark

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[bryan]

You said that ".. inflating your tire to 60 PSI would decrease the probability of having flats."  According the Bicycle Quarterly (Spring 2013 issue, p.43) "..soft tires roll over sharp objects, where harder tires would hammer them into the tread."

That issue devoted around half of its pages to tire performance.  Some other tidbits that might pique this forum's interest:

- "tire pressure has an almost negligible effect on bicycle performance"

- A Schwalbe Marathon is faster than a Vittoria CX over rumble strips but not smooth road or a track.

- "whether the road is smooth or rough, tubular tires and clinchers roll at approximately the same speed...".

- "... very narrow tires roll slower than medium width ones.  Beyond 25mm, additional width no longer provides measurable advantages on very smooth roads, but on rougher surfaces, the lower pressure at which the wider tires can be run greatly improves the cyclist's speed.

I tried not to take any quotes out of context.  It's an interesting read and challenges some of our perceptions.

Don't shoot me, I'm just the messenger.

bryan

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bryan...@gmail.com

[ar...@rogers.com]

I quite agree. They have an update to their original report in the current issue.

Roy

Sent from Windows Mail

[Majed]

Hi Bryan, and thanks for your input.

I have to disagree with this, just imagine that you are running a nearly flat tire, it will take a lot of effort to move the bike.

Another thing, they tried in Mythbusters the same with cars. Over inflating tires were more fuel efficient, which means, it needs less energy to move the vehicle. I guess the same applies for bicycles.

These are my 2 cents in this topic.

Majed

--
M

[ar...@rogers.com]

With respect no one is talking about “nearly flat” tires. Typically 85% of the max recommended is representative. This will also provide an element of passive suspension on coarse and uneven surfaces.Also how can you possibly compare a bike with car tires? The construction technology is quite different- not to mention operating pressure. The Bicycle Quarterly report stresses that sidewall construction of bike tires as being a major consideration.  Significantly, the Grand Tour riders are moving towards wider tires (23-25mm). The very skinny tires of 18-19mm, popular some years ago with club riders seem to have been discontinued. 

In conclusion (again with respect) is to ask you and other cyclists whether they feel that Mythbusters is a more credible source of bicycle technology than “Bicycle Quarterly”.

Cheers

Roy   

[Majed]

Thanks to all who have contributed with their opinions on this matter. I changed my tires to new ones, continental tour ride 28X1.5. The recommended pressure on the tire is 50 PSI. I tried to go with the 50 PSI, it was a drag. Increasing to the max pressure (65 PSI) was much better. Yes the ride was more bumpy, but faster and easier on the knees.

Conclusion:

As for me, I will go with the maximum pressure possible on tires, as it will save my knees !

The nearly flat bike tires is a myth !

Thanks

Majed

--
M

[Larry Parker]

Data points? You said 50psi "was a drag,"  How so? did you ride the same course under similar conditions and check average speeds/HR/power?  One of the points the "fatter-softer" crowd try to make is that we THINK the skinny - harder tires are faster. They give us more feedback, more buzz, and we think we are going faster (and we may be, on smooth roads) but on normal or rough roads, that buzz can be tiring to the upper body and the bounce in the tires as you hit each bump actually slows you down.

 

So I would be very interested if you have real comparable hard data to compare the tire at the two different pressures.  I am not advocating, I think this is an ongoing experiment and needs more info and input.  BQ has done some neat research, but good "scientists" want results that others can repeat and agree with!

 

Larry Parker

[Mark Gardner]

No one is advocating nearly flat tires. As for high pressures, the good news is that they are not slower except on rough surfaces.

[Wayne Estes]

Folks, please don't post short comments with HUNDREDS of lines of
unnecessary quoted text.

Wayne Estes
Oakland, Oregon, USA

[LostInTheTrees]

And where is it that rough surfaces are not the rule, at least in the US? NV seems to do a great job, but where else? In AZ smooth roads are almost nonexistent.

-Bob

Tucson AZ - Eugene OR

[Mark Boyd]

Riding on my 700x42 Travel Conacts at pressures below 50 psi, I don't
notice rough roads nearly as much as I do on my road bike with 700x25
tires at 90 to 100 psi ;-}, but my experience is that there are some
quite smooth roads in Arizona. And I can back that up with images from
my Visiting Old Friends web pages e.g.

https://www.crazyguyonabike.com/doc/page/?o=1&page_id=350446&v=9E

I agree than Nevada has the smoothest roads in the US. I also agree
that the US infrastructure in, in general, crumbling so that there a
lots of poorly maintained roads. With a few exceptions, roads in most
European countries are now smoother than US roads.

Mark

[Matthew J]

> The nearly flat bike tires is a myth !

 First, your not liking something does not make it a myth.

Second, comparing a two wheeled bicycle that weighs less than 40 pounds with a multi-ton 4 wheeled vehicle is just let's say (to be polite) a little daft.  Definitely ride what you like but if you think you've proven something about bike dynamics you are way off.

[bpl...@comcast.net]

-->   and we think we are going faster

 

Seems to me that for most people, that is just fine.  Certainly anyone at their limits whether because they are lugging a load up a mountain, riding the most miles of their life, or just trying to win their first TdF stage is really concerned about efficiency.

 

But given that the debate has raged for literally decades, the differences must be somewhat minor.  So I say if you like the softer ride, go for it.  If you like the more ‘spirited’ ride go for that. 

 

bp

 

From: bicycle...@googlegroups.com [mailto:bicycle...@googlegroups.com] On Behalf Of Larry Parker
Sent: Saturday, May 10, 2014 9:31 AM
To: Majed
Cc: bicycle...@googlegroups.com
Subject: Re: [touring] Re: tire pressure with 700x42 tires

 

Data points? You said 50psi "was a drag,"  How so? did you ride the same course under similar conditions and check average speeds/HR/power?  One of the points the "fatter-softer" crowd try to make is that we THINK the skinny - harder tires are faster. They give us more feedback, more buzz, and we think we are going faster (and we may be, on smooth roads) but on normal or rough roads, that buzz can be tiring to the upper body and the bounce in the tires as you hit each bump actually slows you down.

[ernest breakfield]

Larry,

    i suspect your interpretation of "was a drag" may be a bit off; for many people, something that is a "drag" = "not enjoyable". what is "enjoyable differs between foils, and even changes for folks with time, but has little-to-nothing to do with data points, power measurements, etc.

    for most people that are cycling for the pure enjoyment of cycling, Majed has already done the only experiment necessary; try it both ways and see which is more pleasurable.


cheers!
e