Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

The real reason that clincher PSIs top out at 120 is...

Notices
Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

The real reason that clincher PSIs top out at 120 is...

Old 07-08-08, 05:52 PM
  #1  
Senior Member
Thread Starter
 
Sincitycycler's Avatar
 
Join Date: Mar 2005
Location: "Gosh honey, you pass more like Tony Rominger..."
Posts: 3,218

Bikes: 2005 Scott CR1 Pro - 1992 Panasonix Fixed Conversion 60tx20t

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 1 Time in 1 Post
The real reason that clincher PSIs top out at 120 is...

...companies are afraid of rim failure (according to an ebay bike store mgr).
Is this true?

Looking for a clincher that can go up to 130-140 psi, if this is possible...
__________________
"How did all those 'Keep Off the Grass' signs get there?"
Sincitycycler is offline  
Old 07-08-08, 05:55 PM
  #2  
Mr. Dopolina
 
Bob Dopolina's Avatar
 
Join Date: May 2007
Location: Taiwan
Posts: 10,217

Bikes: KUUPAS, Simpson VR

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 149 Post(s)
Liked 117 Times in 41 Posts
Originally Posted by Sincitycycler
...companies are afraid of rim failure (according to an ebay bike store mgr).
Is this true?

Looking for a clincher that can go up to 130-140 psi, if this is possible...
Any tire rated for 120psi will do 130-140. The problem is with the rim sidewall.
__________________
BDop Cycling Company Ltd.: bdopcycling.com, facebook, instagram



Bob Dopolina is offline  
Old 07-08-08, 06:05 PM
  #3  
Senior Member
 
Join Date: Apr 2005
Location: Northern California
Posts: 10,879
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 104 Post(s)
Likes: 0
Liked 5 Times in 5 Posts
Yes, many lightweight boutique wheels cannot handle 140 psi. However, I've never heard that as a excuse for limiting tire ratings. For example, the popular Vred TriComp is rated for 145 psi: https://www.biketiresdirect.com/produ...il.asp?p=VR4FO

Unless you are riding on a polished wood track, I do not see any reason for using 145 psi.
johnny99 is offline  
Old 07-08-08, 06:36 PM
  #4  
Senior Member
 
Join Date: Apr 2008
Location: Salt Lake City, UT (Formerly Los Angeles, CA)
Posts: 1,145

Bikes: 2008 Cannondale Synapse -- 2014 Cannondale Quick CX

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 212 Post(s)
Likes: 0
Liked 83 Times in 54 Posts
Originally Posted by johnny99
Unless you are riding on a polished wood track, I do not see any reason for using 145 psi.
Only a matter of time before someone posts a photo of a double-clyde in response to that assertion.
daoswald is offline  
Old 07-08-08, 06:45 PM
  #5  
ボケ
 
Join Date: Jan 2007
Location: Denver, CO
Posts: 412

Bikes: Cannondale CAAD 9

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I've got the cheapest Vittoria Zaffiros (700x25C) on my commuter. They're rated for 130 psi.
Seedy J is offline  
Old 07-08-08, 07:15 PM
  #6  
Roadie
 
brian416's Avatar
 
Join Date: Oct 2007
Posts: 1,461
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked 11 Times in 8 Posts
My dad runs 130psi with ksyriums, 5k miles and no problems, I usually stick with 110-120 with my ksyriums though
brian416 is offline  
Old 07-08-08, 07:22 PM
  #7  
Senior Member
 
billallbritten's Avatar
 
Join Date: Sep 2005
Location: Murray, KY
Posts: 783

Bikes: Trek 7500 FX (2005)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked 0 Times in 0 Posts
Originally Posted by Sincitycycler
...companies are afraid of rim failure (according to an ebay bike store mgr).
Is this true?

Looking for a clincher that can go up to 130-140 psi, if this is possible...
Vredestein Fortezza Tricomps, rated to 175, I wouldn't ride'm at that though. Campy rims are only rated to 145.
__________________
His: Trek 7500FX
Specialized Roubaix
Spouse: Trek 7.5FX

billallbritten is offline  
Old 07-08-08, 07:43 PM
  #8  
Senior Member
 
garysol1's Avatar
 
Join Date: Apr 2005
Location: Traverse City Michigan
Posts: 10,244
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 78 Post(s)
Liked 17 Times in 11 Posts
Originally Posted by Sincitycycler
..
Looking for a clincher that can go up to 130-140 psi,
Why?
__________________
BMC Roadmachine
Kona Jake the Snake
garysol1 is offline  
Old 07-08-08, 07:45 PM
  #9  
post-ironic
 
Wested's Avatar
 
Join Date: May 2008
Location: Brooklyn, NY
Posts: 802

Bikes: CAAD 12, Lemond Maillot Jaune

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 75 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by garysol1
Why?
+1
Wested is offline  
Old 07-08-08, 07:45 PM
  #10  
2-Cyl, 1/2 HP @ 90 RPM
 
slvoid's Avatar
 
Join Date: Oct 2003
Location: NYC
Posts: 15,762

Bikes: 04' Specialized Hardrock Sport, 03' Giant OCR2 (SOLD!), 04' Litespeed Firenze, 04' Giant OCR Touring, 07' Specialized Langster Comp

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 4 Times in 4 Posts
My reynolds dv carbon clincher rims go up to 160psi.
slvoid is offline  
Old 07-08-08, 08:26 PM
  #11  
that bike nut
 
BikingGrad80's Avatar
 
Join Date: Jul 2007
Location: Chicago north
Posts: 939

Bikes: 2010 Motobecane Immortal Force 90' Trek 1400; 90' Trek 850; 06' Trek 520; 01 Iron Horse Victory

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 25 Post(s)
Likes: 0
Liked 3 Times in 2 Posts
I usually ride at 120 psi. Why go higher?
BikingGrad80 is offline  
Old 07-08-08, 08:43 PM
  #12  
Senior Member
 
Join Date: Jun 2006
Location: Canton, MI
Posts: 313

Bikes: Fuji Newest 4.0 (my first road bike)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Wested
+1
+2

I float around 200lbs. and usually leave mine at 100psi. I never go past 120.
Brian6751 is offline  
Old 07-08-08, 09:28 PM
  #13  
Peloton Shelter Dog
 
patentcad's Avatar
 
Join Date: Nov 2005
Location: Chester, NY
Posts: 90,508

Bikes: 2017 Scott Foil, 2016 Scott Addict SL, 2018 Santa Cruz Blur CC MTB

Mentioned: 74 Post(s)
Tagged: 2 Thread(s)
Quoted: 1142 Post(s)
Liked 28 Times in 22 Posts
Originally Posted by BikingGrad80
I usually ride at 120 psi. Why go higher?
Because it is there.

I ride my Zipp 404 tubular wheels with Conti Sprinters @ 160lbs all the time.
patentcad is offline  
Old 07-08-08, 09:34 PM
  #14  
Senior Member
 
zonatandem's Avatar
 
Join Date: Dec 2003
Location: Tucson, AZ
Posts: 11,016

Bikes: Custom Zona c/f tandem + Scott Plasma single

Mentioned: 3 Post(s)
Tagged: 1 Thread(s)
Quoted: 77 Post(s)
Likes: 0
Liked 19 Times in 11 Posts
That's total BS from the 'expert' manager at your LBS! Find another shop!!!
Run Maxxis Courchevels on Topolino wheels @ 130 lbs.
zonatandem is offline  
Old 07-08-08, 09:39 PM
  #15  
Senior Member
 
Join Date: Jan 2008
Location: Georgia
Posts: 1,753
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Bontragers carbon clinchers are rated to 120psi. High end Mavics say not to go higher than 138psi.
Cdy291 is offline  
Old 07-08-08, 10:25 PM
  #16  
Senior Member
 
Join Date: Oct 2004
Posts: 5,250
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 7 Times in 7 Posts
Different rims are rated for different PSI levels. But, assuming a 140 PSI tire is the perfect width for a given rim, it probably is going to stay mounted without problems.

However, who NEEDS a PSI over 120 pounds? The best PSI level for a tire is the one that yields 15% deflection of the sidewalls under the rider's weight. With the 23mm tires popular with guys who pretend to race bikes, 15% deflection can be obtained at 70 PSI for light riders, and 90 PSI for average riders. A rider over 180 pounds might need to go as high as 120 PSI to get 15% deflection.
alanbikehouston is offline  
Old 07-08-08, 10:27 PM
  #17  
2-Cyl, 1/2 HP @ 90 RPM
 
slvoid's Avatar
 
Join Date: Oct 2003
Location: NYC
Posts: 15,762

Bikes: 04' Specialized Hardrock Sport, 03' Giant OCR2 (SOLD!), 04' Litespeed Firenze, 04' Giant OCR Touring, 07' Specialized Langster Comp

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 4 Times in 4 Posts
Originally Posted by alanbikehouston
Different rims are rated for different PSI levels. But, assuming a 140 PSI tire is the perfect width for a given rim, it probably is going to stay mounted without problems.

However, who NEEDS a PSI over 120 pounds? The best PSI level for a tire is the one that yields 15% deflection of the sidewalls under the rider's weight. With the 23mm tires popular with guys who pretend to race bikes, 15% deflection can be obtained at 70 PSI for light riders, and 90 PSI for average riders. A rider over 180 pounds might need to go as high as 120 PSI to get 15% deflection.
That depends on how the tires are constructed. Some of them are so soft and supple that 140 psi feels like 110.
slvoid is offline  
Old 07-08-08, 10:34 PM
  #18  
Senior Member
 
Join Date: Aug 2006
Posts: 1,160
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 154 Post(s)
Liked 14 Times in 11 Posts
Originally Posted by slvoid
That depends on how the tires are constructed. Some of them are so soft and supple that 140 psi feels like 110.
Color me skeptical that 2mm of "supple" rubber is going to make a "140 psi tire feel like 110".

- Mark
markjenn is offline  
Old 07-08-08, 10:39 PM
  #19  
2-Cyl, 1/2 HP @ 90 RPM
 
slvoid's Avatar
 
Join Date: Oct 2003
Location: NYC
Posts: 15,762

Bikes: 04' Specialized Hardrock Sport, 03' Giant OCR2 (SOLD!), 04' Litespeed Firenze, 04' Giant OCR Touring, 07' Specialized Langster Comp

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 4 Times in 4 Posts
Originally Posted by markjenn
Color me skeptical that 2mm of "supple" rubber is going to make a "140 psi tire feel like 110".

- Mark
It's not the 2mm, it's how they're constructed. Replace 2mm of "supple" rubber with 2mm of 90 A shore rubber and 110psi's gonna feel like 140.
slvoid is offline  
Old 07-08-08, 10:39 PM
  #20  
Senior Member
 
Join Date: Oct 2004
Posts: 5,250
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 7 Times in 7 Posts
Yes, at 15% deflection, some tires feel more supple than others. Continental tires tend to feel less supple than most until you get to about 20% deflection. Vittoria makes some tires that feel supple at 10
% deflection.

But, at 140 PSI, NO tire feels "supple", unless you weigh over 250 pounds, because the sidewalls have ZERO deflection...they are functioning as blocks of wood under the weight of a 160 pound rider.

If a 160 pound guy rides at 140 PSI, any tire is gonna feel like riding on wooden tires. If a tire is over-inflated and has ZERO deflection of the side walls, it feels absolutely identical to every other tire that has ZERO deflection...it feels like every bump is going directly to your hands and to your rear.

To get a tire's best shock absorption and feel, the sidewalls must sag (slightly) and flex under the rider's weight and in reaction to pavement conditions. For very light riders (110 pounds or 120 pounds) it can be necessary to ride at 70 PSI or 75 PSI to get the amount of sidewall flexing that a 180 pound rider obtains at 120 PSI.

An interesting experiment for 180 pound guys who ride at 120 PSI is to ride for a week with the front tires at 95 PSI and the back tires at 100 PSI. The first day, they think "my tires feel heavy...my bike feels slow". After a week at 100 PSI, they go back to 120 PSI. Then they think "Who tore up the concrete on these streets...I'm getting beaten to death out here".
alanbikehouston is offline  
Old 07-08-08, 10:44 PM
  #21  
2-Cyl, 1/2 HP @ 90 RPM
 
slvoid's Avatar
 
Join Date: Oct 2003
Location: NYC
Posts: 15,762

Bikes: 04' Specialized Hardrock Sport, 03' Giant OCR2 (SOLD!), 04' Litespeed Firenze, 04' Giant OCR Touring, 07' Specialized Langster Comp

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 4 Times in 4 Posts
Originally Posted by alanbikehouston
But, at 140 PSI, NO tire feels "supple", unless you weigh over 250 pounds, because the sidewalls have ZERO deflection... they are functioning as blocks of wood under the weight of a 160 pound rider.
Hell I have a pair of michelin PR3's right now on a spare wheelset being "stretched out" @ 130psi and I can easily deflect the sidewall by pinching on it with my fingers. I've had 145 psi on my reynolds wheels and vittorias and I've been able to see the sidewalls bulge at the contact points as I ride. I don't need a caliper to tell me that they deflect... but I have a pair of calipers that measure down to 0.0005", a very accurate pressure gage, and I'm north of 150. Are you willing to put money on that?
slvoid is offline  
Old 07-08-08, 10:46 PM
  #22  
Me Likey Bikey
 
neurocycler's Avatar
 
Join Date: Feb 2007
Location: Somewhere in Competent Mediocrity
Posts: 642
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by patentcad
Because it is there.

I ride my Zipp 404 tubular wheels with Conti Sprinters @ 160lbs all the time.
Ata boy.
neurocycler is offline  
Old 07-08-08, 11:05 PM
  #23  
^_^
 
Industrial's Avatar
 
Join Date: Jun 2007
Location: New Hampshire
Posts: 657

Bikes: Cannondale System Six, Specialized FSR-XC, Specialized Langster, Univega Arrow Spot, Raleigh Sports

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
My neuvation r28 wheels seem to hold 125-130 psi fine. The wheelset that came stock on my langster(alex r500) went BOOM anywhere past 120 with the same tires and tubes. It's definately the rims.
Industrial is offline  
Old 07-09-08, 12:46 AM
  #24  
A little North of Hell
 
Join Date: Mar 2006
Posts: 4,892
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 71 Post(s)
Likes: 0
Liked 4 Times in 4 Posts
https://www.lewracing.com/proVC1rims.html
Soil_Sampler is offline  
Old 07-09-08, 12:55 AM
  #25  
Made in Norway
 
Lectron's Avatar
 
Join Date: Oct 2004
Location: Norway
Posts: 1,676
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked 18 Times in 6 Posts
In most cases, going higher than 100 psi will increase your rolling resistance
-Of course that depends on the riders weight, but unlike the steel drum and 30kg
load during 'rolling resistance testing', where actually a steel wheel would preform
good, we can benefit from a little deflection.

A wider tire (same preassure) would decrease rolling resistance even more

Last edited by Lectron; 07-09-08 at 01:01 AM.
Lectron is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.