Go Back  Bike Forums > Bike Forums > Clydesdales/Athenas (200+ lb / 91+ kg)
Reload this Page >

Tire Pressure, should tire deform when i sit down?

Notices
Clydesdales/Athenas (200+ lb / 91+ kg) Looking to lose that spare tire? Ideal weight 200+? Frustrated being a large cyclist in a sport geared for the ultra-light? Learn about the bikes and parts that can take the abuse of a heavier cyclist, how to keep your body going while losing the weight, and get support from others who've been successful.

Tire Pressure, should tire deform when i sit down?

Old 05-21-14, 04:36 PM
  #1  
Senior Member
Thread Starter
 
WVU_Engineer's Avatar
 
Join Date: May 2014
Location: Southern Maryland
Posts: 112

Bikes: Raleigh Venture

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Tire Pressure, should tire deform when i sit down?

Part of why I bought a comfort bike and not a hybrid was due to the wider tire being able to handle more weight and give a smoother ride. I pump my tires up to max pressure which is 65 psi but I notice that my rear tire is still deformed when I sit down, is this normal? Should I try going to 70 psi or will it go boom?
WVU_Engineer is offline  
Old 05-21-14, 04:40 PM
  #2  
Living 'n Dying in ¾-Time
 
JBHoren's Avatar
 
Join Date: Dec 2008
Location: Greenacres, FL
Posts: 642
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 27 Post(s)
Liked 4 Times in 2 Posts
Dude! We're Clydesdales, not "Tinkerbelles" -- of course it's gonna deform
JBHoren is offline  
Old 05-21-14, 05:22 PM
  #3  
Senior Member
 
Null66's Avatar
 
Join Date: Jun 2013
Location: Garner, NC 27529
Posts: 2,110

Bikes: Built up DT, 2007 Fuji tourer (donor bike, RIP), 1995 1220 Trek

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked 2 Times in 2 Posts
Google bicycle tire pressure calculator, pick one.

Target is for tire to deform 15%...
Null66 is offline  
Old 05-21-14, 05:33 PM
  #4  
Just Plain Slow
 
Join Date: Mar 2010
Location: Santa Clarita, CA
Posts: 6,038

Bikes: Lynskey R230

Mentioned: 40 Post(s)
Tagged: 0 Thread(s)
Quoted: 297 Post(s)
Likes: 0
Liked 5 Times in 5 Posts
How much have you ridden? You getting any pinch-flats? If you are, more pressure. And in case you don't know, you can tell a pinch-flat because the tube looks like it was bitten by a rattle snake. It'll have two holes, actually created by the tire flexing out (with the tube stretching with it), then the rim coming down and pinching the tube between the rim and the ground.

Attached Images
File Type: jpg
image004.jpg (9.1 KB, 10 views)
PhotoJoe is offline  
Old 05-21-14, 06:05 PM
  #5  
Senior Member
 
awfulwaffle's Avatar
 
Join Date: Jul 2013
Location: Novi, MI
Posts: 539

Bikes: Franken-mountain bike, mid-90s Performance TR1000, 1990 Cannondale ST400

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Absolutely normal. Like PhotoJoe said, as long as you're not getting pinch flats you're OK.
awfulwaffle is offline  
Old 05-21-14, 07:02 PM
  #6  
Senior Member
Thread Starter
 
WVU_Engineer's Avatar
 
Join Date: May 2014
Location: Southern Maryland
Posts: 112

Bikes: Raleigh Venture

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Cool, I knew it would deform it just seemed like a lot but it is hard to judge looking down between my legs and hopefully the neighbors don't think I'm checking myself out.
WVU_Engineer is offline  
Old 05-21-14, 09:20 PM
  #7  
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,505

Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter

Mentioned: 139 Post(s)
Tagged: 1 Thread(s)
Quoted: 5681 Post(s)
Liked 2,386 Times in 1,320 Posts
I hate to sound snide but tires aren't magic. They have to deform as they are loaded.

Go outside and look at a few car tires. They all have the characteristic bulge at the bottom. Bike tires work the same way, and will have the same characteristic bulge.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

Just because I'm tired of arguing, doesn't mean you're right.

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline  
Old 05-21-14, 10:56 PM
  #8  
SuperGimp
 
TrojanHorse's Avatar
 
Join Date: Mar 2010
Location: Whittier, CA
Posts: 13,346

Bikes: Specialized Roubaix

Mentioned: 147 Post(s)
Tagged: 0 Thread(s)
Quoted: 1106 Post(s)
Liked 64 Times in 47 Posts
Originally Posted by WVU_Engineer
Part of why I bought a comfort bike and not a hybrid was due to the wider tire being able to handle more weight and give a smoother ride. I pump my tires up to max pressure which is 65 psi but I notice that my rear tire is still deformed when I sit down, is this normal? Should I try going to 70 psi or will it go boom?
What is the max inflation pressure for your tires? It's stamped on the sidewall of the tire. Don't go over that, but as a clyde you should probably be right at that number, and check it before each ride (or at least daily)
TrojanHorse is offline  
Old 05-21-14, 11:07 PM
  #9  
Member
 
Join Date: Aug 2012
Location: Nor Cal
Posts: 28

Bikes: Specialized Secteur Sport Disc,Giant Escape 2,Raleigh Capri 1.0, New to me Specialized Roubaix Comp

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by FBinNY
Go outside and look at a few car tires. They all have the characteristic bulge at the bottom.
Someone beat me to it. The deformity is normal.
veerod82 is offline  
Old 05-22-14, 06:46 AM
  #10  
Senior Member
 
IBOHUNT's Avatar
 
Join Date: Nov 2011
Location: Western Maryland - Appalachian Mountains
Posts: 4,026

Bikes: Motobecane Fantom Cross; Cannondale Supersix replaced the Giant TCR which came to an untimely death by truck

Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 126 Post(s)
Liked 26 Times in 10 Posts
The only tires that don't deform are solid rubber *OR* those on the 1931 W-30. Neither would be my choice to ride on...
IBOHUNT is offline  
Old 05-22-14, 02:45 PM
  #11  
Senior Member
Thread Starter
 
WVU_Engineer's Avatar
 
Join Date: May 2014
Location: Southern Maryland
Posts: 112

Bikes: Raleigh Venture

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Like I said above, of course I knew there would be deformation but I should have written "more than expected".

What I was getting at was my tires have a recommended pressure of 45-65 psi, I ran at 70 psi a couple days ago and it made a noticeable difference and was curious if any other big guys did this.

Last edited by WVU_Engineer; 05-22-14 at 02:47 PM. Reason: puncutation
WVU_Engineer is offline  
Old 05-22-14, 04:34 PM
  #12  
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,505

Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter

Mentioned: 139 Post(s)
Tagged: 1 Thread(s)
Quoted: 5681 Post(s)
Liked 2,386 Times in 1,320 Posts
There's usually very generous safety margins built into tire pressure ratings. After all they have to account for inaccurate gauges and pressure climb from braking heat and/or hot pavements.

So fee free to exceed rated pressures by 25% or so (usually) if it improves performance. Finding ideal pressure is about experimentation, and different people of the same weight, and using identical tires, won't always agree on what works best, which is OK. What's best for you is what you think is best for you, so feel free to exceed rated pressure, but be aware that heat can cause further increase.

BTW- my way of optimizing pressure, is to raise by degrees (5psi or so) over time, and riding for a while before raising again. When I find a level where the drawbacks -- skittish handling, harsh ride, etc. -- become noticeable, I back off to the last pressure that rode nice.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

Just because I'm tired of arguing, doesn't mean you're right.

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline  
Old 05-22-14, 07:26 PM
  #13  
Senior Member
 
Join Date: Mar 2012
Location: southeastern PA - a mile west of Philadelphia
Posts: 430
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by TrojanHorse
What is the max inflation pressure for your tires? It's stamped on the sidewall of the tire. Don't go over that, but as a clyde you should probably be right at that number, and check it before each ride (or at least daily)
+1
Gnosis is offline  
Old 05-22-14, 08:59 PM
  #14  
Member
 
photogeekgirl's Avatar
 
Join Date: Apr 2014
Location: Beaver Dam, WI
Posts: 28

Bikes: Schwinn Clairmont "Suzie"

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by FBinNY
There's usually very generous safety margins built into tire pressure ratings. After all they have to account for inaccurate gauges and pressure climb from braking heat and/or hot pavements.

So fee free to exceed rated pressures by 25% or so (usually) if it improves performance. Finding ideal pressure is about experimentation, and different people of the same weight, and using identical tires, won't always agree on what works best, which is OK. What's best for you is what you think is best for you, so feel free to exceed rated pressure, but be aware that heat can cause further increase.

BTW- my way of optimizing pressure, is to raise by degrees (5psi or so) over time, and riding for a while before raising again. When I find a level where the drawbacks -- skittish handling, harsh ride, etc. -- become noticeable, I back off to the last pressure that rode nice.
I was wondering the same thing as the op. Thanks for this info; good to know!
photogeekgirl is offline  
Old 05-22-14, 10:02 PM
  #15  
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Posts: 12,367

Bikes: 15 Kinesis Racelight 4S, 76 Motebecane Gran Jubilée, 17 Dedacciai Gladiatore2, 12 Breezer Venturi, 09 Dahon Mariner, 12 Mercier Nano, 95 DeKerf Team SL, 19 Tern Rally, 21 Breezer Doppler Cafe+, 19 T-Lab X3, 91 Serotta CII

Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 3071 Post(s)
Liked 1,624 Times in 999 Posts
Originally Posted by FBinNY
Go outside and look at a few car tires. They all have the characteristic bulge at the bottom. Bike tires work the same way, and will have the same characteristic bulge.
Well, that's not true. It depends on sidewall height, construction, rim bead width, and width ratio between tire and wheel.

For example:

chaadster is offline  
Old 05-22-14, 11:46 PM
  #16  
just pedal
 
donalson's Avatar
 
Join Date: Aug 2008
Location: Houston, TX
Posts: 979

Bikes: Surly Disc Trucker, trek 560

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 18 Post(s)
Liked 1 Time in 1 Post
on a road riding setup you are ideally looking for about a 15% drop... different tires will be slightly different but it's a good average... to get this you need to figure out the height of the tire from ground to rim... then take 15% of that number, when you sit on the bike (in your proper riding position) that is the height the rim edge should sit... this requires a friend and in reality I don't know any normal rider who's done this.

on a MTB out on the trail I tend to go with a more generic of "enough" I always started around 35psi (29er so larger air volume allows lower pressure than similar sized tire 26er)... if I felt the tire was rolling out from under me or I ever felt it hit the rim (or got a snake bite) i'd add a bit of pressure, on the other end I'd let out a bit of pressure as I'd ride to get the pressure low enough to what felt right... this is far easier to do and more important on a rigid bike.

here is a helpful calculator, but its only a limited size and for 700c tires.
Bicycle tire pressure calculator

in my experience I would say that most larger (250+ lbs) road clyds are prob running too little pressure based on the 15% drop rule of thumb and that most skinny riders are running too high of pressure
donalson is offline  
Old 05-23-14, 04:43 AM
  #17  
Senior Member
 
mrodgers's Avatar
 
Join Date: Aug 2013
Location: Western PA
Posts: 1,649

Bikes: 2014 Giant Escape 1

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 289 Post(s)
Liked 29 Times in 20 Posts
Originally Posted by chaadster
Well, that's not true. It depends on sidewall height, construction, rim bead width, and width ratio between tire and wheel.

For example:

True though for normal properly fitted and pressurized tires. Those things are ridiculous.
mrodgers is offline  
Old 05-23-14, 08:02 AM
  #18  
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Posts: 12,367

Bikes: 15 Kinesis Racelight 4S, 76 Motebecane Gran Jubilée, 17 Dedacciai Gladiatore2, 12 Breezer Venturi, 09 Dahon Mariner, 12 Mercier Nano, 95 DeKerf Team SL, 19 Tern Rally, 21 Breezer Doppler Cafe+, 19 T-Lab X3, 91 Serotta CII

Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 3071 Post(s)
Liked 1,624 Times in 999 Posts
Originally Posted by mrodgers
True though for normal properly fitted and pressurized tires. Those things are ridiculous.
That's still incorrect. Many stock offerings on wide, lo-pro rubber exhibit no bulging.

I also think that, rather than being ridiculous, the above pictured wheels are super stylish, and while impractical (in terms of damage risk and street ride quality, anyway), definitely make a statement about wheels and tires, specifically that the boundaries are probably way beyond what you think you know.

Stock BMW M3 '14:

chaadster is offline  
Old 05-23-14, 08:39 AM
  #19  
Member
 
Join Date: Aug 2012
Location: Nor Cal
Posts: 28

Bikes: Specialized Secteur Sport Disc,Giant Escape 2,Raleigh Capri 1.0, New to me Specialized Roubaix Comp

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I think if someone put a heavy enough load in those low pro cars, (like a clyde on a road bike) the tires would bulge. "Think" being the key word.
veerod82 is offline  
Old 05-23-14, 09:08 AM
  #20  
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Posts: 12,367

Bikes: 15 Kinesis Racelight 4S, 76 Motebecane Gran Jubilée, 17 Dedacciai Gladiatore2, 12 Breezer Venturi, 09 Dahon Mariner, 12 Mercier Nano, 95 DeKerf Team SL, 19 Tern Rally, 21 Breezer Doppler Cafe+, 19 T-Lab X3, 91 Serotta CII

Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 3071 Post(s)
Liked 1,624 Times in 999 Posts
Originally Posted by veerod82
I think if someone put a heavy enough load in those low pro cars, (like a clyde on a road bike) the tires would bulge. "Think" being the key word.
There is a little factor known as suspension...
chaadster is offline  
Old 05-23-14, 09:11 AM
  #21  
SuperGimp
 
TrojanHorse's Avatar
 
Join Date: Mar 2010
Location: Whittier, CA
Posts: 13,346

Bikes: Specialized Roubaix

Mentioned: 147 Post(s)
Tagged: 0 Thread(s)
Quoted: 1106 Post(s)
Liked 64 Times in 47 Posts
Originally Posted by chaadster
There is a little factor known as suspension...
And you don't think the suspension transfers the weight to the tire?

Of course those tires are bulging, it's just not as noticeable as it is on other tires.
TrojanHorse is offline  
Old 05-23-14, 09:20 AM
  #22  
Just Plain Slow
 
Join Date: Mar 2010
Location: Santa Clarita, CA
Posts: 6,038

Bikes: Lynskey R230

Mentioned: 40 Post(s)
Tagged: 0 Thread(s)
Quoted: 297 Post(s)
Likes: 0
Liked 5 Times in 5 Posts
I suspect the OP really isn't concerned with the tires on his car bulging.
PhotoJoe is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Bahamut5098
General Cycling Discussion
3
11-19-14 09:57 AM
Surfmonkey
Bicycle Mechanics
7
11-24-13 12:48 PM
ModelTFan01
Road Cycling
42
08-10-12 07:10 AM
Porkponey
Road Cycling
18
06-22-11 02:33 PM
papertigerbob
Bicycle Mechanics
11
06-17-10 10:23 AM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


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.