Go Back  Bike Forums > Bike Forums > General Cycling Discussion
Reload this Page >

Is my tire pressure high enough?

General Cycling Discussion Have a cycling related question or comment that doesn't fit in one of the other specialty forums? Drop on in and post in here! When possible, please select the forum above that most fits your post!

Is my tire pressure high enough?

Old 08-24-08, 01:37 PM
  #1  
Digitalwave
Junior Member
Thread Starter
 
Join Date: Aug 2008
Posts: 20
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Is my tire pressure high enough?

After a 10 year hiatus from any serious riding (I raced BMX growing up) I recently picked up a vintage Cannondale SR300 (12 speed) along with a vintage Fuji del Rey (converting to single speed).

One thing I have noticed with both bikes is that even when I seemingly inflate the rear tires properly, they seem to "distort" more under my weight than the fronts do when I am riding. Both bikes has 700x23c tires. I weight 185lbs. When I look down while riding the bike you can see the sidewall of the rear tire is slightly distorted even though I am inflating to 120psi, and the front looks normal.

I am guessing this is simply because more of my weight is on the back wheel than the front, but I want to make sure that I don't have another issue like a faulty pump pressure gauge or anything.

Thanks in advance, and sorry for the fairly lame newbie question. I couldn't find a proper search term that gave back any results pertaining to this question, so if it's been covered before, I'm sorry.
Digitalwave is offline  
Old 08-24-08, 01:41 PM
  #2  
tsl
Plays in traffic
 
tsl's Avatar
 
Join Date: May 2006
Location: Rochester, NY
Posts: 6,968

Bikes: 1996 Litespeed Classic, 2006 Trek Portland, 2013 Ribble Winter/Audax, 2016 Giant Talon 4

Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 66 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Try searching on "tire pressure formula" select the first thread and scroll down to post #3. You'll find a formula many of us use. It takes into account tire size and rider weight, returning a good starting point for front and rear pressures. Adjust for personal preference from there.
tsl is offline  
Old 08-24-08, 01:55 PM
  #3  
Retro Grouch 
Senior Member
 
Retro Grouch's Avatar
 
Join Date: Feb 2004
Location: St Peters, Missouri
Posts: 29,272

Bikes: Catrike 559 I own some others but they don't get ridden very much.

Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 1164 Post(s)
Liked 35 Times in 26 Posts
Should be adequate.

I weigh around 200 lbs and use 100 psi front and 110 psi rear on my road bike with 23mm tires. I have a good friend who is about your weight. He feels that his tires handle "squishy" if they have less than 120 psi. I guess that means that you're in the reasonable range.
Retro Grouch is offline  
Old 08-24-08, 04:04 PM
  #4  
DieselDan
Senior Member
 
DieselDan's Avatar
 
Join Date: Mar 2003
Location: Beaufort, South Carolina, USA and surrounding islands.
Posts: 8,522

Bikes: Cannondale R500, Motobecane Messenger

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
You can't change the laws of chemistry and physics. Your weight will cause the side wall to flex no matter what air pressure.
DieselDan is offline  
Old 08-24-08, 07:21 PM
  #5  
Digitalwave
Junior Member
Thread Starter
 
Join Date: Aug 2008
Posts: 20
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
You can't change the laws of chemistry and physics. Your weight will cause the side wall to flex no matter what air pressure.
Exactly what I thought. Thank you very much for confirming!
Digitalwave is offline  
Old 08-24-08, 09:00 PM
  #6  
JanMM
rebmeM roineS
 
JanMM's Avatar
 
Join Date: Jan 2006
Location: Metro Indy, IN
Posts: 15,484

Bikes: RANS V3 ti, RANS V-Rex, RANS Screamer

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 469 Post(s)
Liked 24 Times in 23 Posts
You could get a new gauge to see if the pump gauge is accurate.
JanMM is offline  
Old 08-25-08, 06:22 PM
  #7  
Velo Dog
Senior Member
 
Join Date: Jun 2004
Location: Northern Nevada
Posts: 3,811
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
The rear is carrying a lot more of your weight than the front; that's why it distorts. In any case, though, I think 23mm is too small for a rider your size. Cycling is pretty much a sport of midgets, where Miguel Indurain (175 pounds in his prime) was once described as "a giant." What works for the 140-pound pro riders isn't necessarily right for everybody.
I'm older and slower now, but when I was younger and faster I weighed 195, and going from 23mm to 28mm and then 32mm tires made me much more comfortable without slowing me down at all. Eventually I wound up faster, because I could ride 50 percent longer.
Grant Petersen at Rivendell, who knows a lot about this, doesn't recommend 23mm tires for riders over about 140 pounds, and in my experience he's right. FWIW, not that anybody who wants to go fast should imitate me, I do most of my riding these days on 35mm tires at 75-80psi, and I'm not going back to skinny rubber.
Velo Dog is offline  
Old 08-25-08, 08:09 PM
  #8  
Digitalwave
Junior Member
Thread Starter
 
Join Date: Aug 2008
Posts: 20
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I never thought of that. These tires have some meat left on them but when it's time to replace I will bump up the size. Thanks!
Digitalwave is offline  
Old 08-26-08, 12:02 PM
  #9  
chucko58
Getting older and slower
 
Join Date: Apr 2008
Location: Silicon Valley, CA, USA
Posts: 102

Bikes: Beat-up commuter, Chumba XCL for the dirt

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I recall reading that the typical weight distribution is 40% front, 60% rear, so I try to set my tire pressures accordingly. Right now on my Long Haul Trucker with 700C x 35 tires I'm using 60 PSI front, 85 PSI rear (the tire's rated max). It seems to work nicely for me.
chucko58 is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
RhodeRunner
General Cycling Discussion
6
03-25-10 07:50 PM
superduper54
Singlespeed & Fixed Gear
8
07-03-09 01:48 PM
crazy bmxer
BMX
12
01-28-06 09:06 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


Thread Tools
Search this Thread

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

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.