Cyclocross Racing Discuss pro racing, the big races, and even the small backyard races. Don't forget to update all the members with your own race results.

Tire Pressure Question

Reply

Old 09-26-18, 11:50 AM
  #1  
Abe_Froman
Senior Member
Thread Starter
 
Abe_Froman's Avatar
 
Join Date: Aug 2016
Location: Chicago
Posts: 2,286

Bikes: Marin Four Corners, 1960's Schwinn Racer in middle of restoration, mid 70s Motobecane Grand Touring, various other heaps.

Mentioned: 43 Post(s)
Tagged: 0 Thread(s)
Quoted: 7957 Post(s)
Tire Pressure Question

So, I've done a handful of races, and am still trying to figure out tire pressure. Running tubes currently. My question is this...SHOULD the tire be folding over/deforming in a corner, or is this something to avoid? My back tire has been deforming on harder corners. I've got it at 30psi right now. I'm thinkiing ~35psi or so might be more effective...but eh. Figured I'd have the community weight in.
Abe_Froman is offline  
Reply With Quote
Old 09-26-18, 12:12 PM
  #2  
wgscott
VectorPotential sensitive
 
wgscott's Avatar
 
Join Date: Jul 2013
Location: The Timbers of Fennario (CL77)
Posts: 3,688

Bikes: Steel

Mentioned: 47 Post(s)
Tagged: 0 Thread(s)
Quoted: 1915 Post(s)
I'm no expert, but I would suggest it should not be folding. Deforming is normal. 35psi seems low unless they are quite wide (how wide?).
wgscott is offline  
Reply With Quote
Old 09-26-18, 12:42 PM
  #3  
ldmataya 
Senior Member
 
ldmataya's Avatar
 
Join Date: Jan 2009
Location: Mt. Horeb, Wisconsin
Posts: 453
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 41 Post(s)
Deforming - sure, but I'm not sure to what extent you think it is bad. When cornering hard at low pressure, you should feel the tire grabbing turf or even slipping out slightly, and you will feel the rim moving around a bit - all normal. But if it feels like a flat rear would feel on gentle cornering, where the rim is obviously moving a lot relative to the tire, then you probably don't have a high quality rim-tire combo if indeed you have 30psi in a 33c wide tire. When running tubeless I am at 24/26 front/rear and I weigh 155. 30-35 would feel rock hard and would be slower on bumpy ground. Pros running tubeless clinchers are in my ballpark, definitely lower if they are smaller than me. But they have high quality tubeless setups (where the bead pops on with a loud snap as you inflate them). Occasionally I've had to stick a tube into my tubleless setup, I keep it at 26 and don't worry about pinch flats - its just a race.
ldmataya is offline  
Reply With Quote
Old 09-26-18, 12:58 PM
  #4  
KraneXL
🎅🏼 🎄 🦌
 
KraneXL's Avatar
 
Join Date: Feb 2015
Location: La-la Land, CA
Posts: 2,216

Bikes: Cannondale Quick SL1 Bike - 2014

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 1742 Post(s)
Originally Posted by Abe_Froman View Post
So, I've done a handful of races, and am still trying to figure out tire pressure. Running tubes currently. My question is this...SHOULD the tire be folding over/deforming in a corner, or is this something to avoid? My back tire has been deforming on harder corners. I've got it at 30psi right now. I'm thinkiing ~35psi or so might be more effective...but eh. Figured I'd have the community weight in.
Depends on the pressure rating, surface, type of tire, and weight of the rider (all of which you excluded). In all cases there is a range of acceptability according to the rider's preference.
KraneXL is offline  
Reply With Quote
Old 09-26-18, 01:12 PM
  #5  
Abe_Froman
Senior Member
Thread Starter
 
Abe_Froman's Avatar
 
Join Date: Aug 2016
Location: Chicago
Posts: 2,286

Bikes: Marin Four Corners, 1960's Schwinn Racer in middle of restoration, mid 70s Motobecane Grand Touring, various other heaps.

Mentioned: 43 Post(s)
Tagged: 0 Thread(s)
Quoted: 7957 Post(s)
Originally Posted by KraneXL View Post
Depends on the pressure rating, surface, type of tire, and weight of the rider (all of which you excluded). In all cases there is a range of acceptability according to the rider's preference.
Sorry. I'm 190lbs, on 35mm all purpose cross tires. No idea what the rating is...but I really doubt that makes any difference.

Thinking of getting a set of Compass Steilacoom tires and running them tubeless....but just worrying about tubed setup right now.
Abe_Froman is offline  
Reply With Quote
Old 09-26-18, 01:49 PM
  #6  
justin1138
Senior Member
 
justin1138's Avatar
 
Join Date: Apr 2013
Location: Portland, OR
Posts: 433

Bikes: yes...

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Originally Posted by Abe_Froman View Post
Sorry. I'm 190lbs, on 35mm all purpose cross tires.
Similar weight and tire set up, I have my pressure around 35#'s. The front is usually 1-2#'s lower than the rear.

I like to feel it out in the yard a day or two before racing (so there's no surprises), and add/subtract pressure so there's not too much rim hitting the ground.
justin1138 is offline  
Reply With Quote
Old 09-26-18, 02:36 PM
  #7  
Abe_Froman
Senior Member
Thread Starter
 
Abe_Froman's Avatar
 
Join Date: Aug 2016
Location: Chicago
Posts: 2,286

Bikes: Marin Four Corners, 1960's Schwinn Racer in middle of restoration, mid 70s Motobecane Grand Touring, various other heaps.

Mentioned: 43 Post(s)
Tagged: 0 Thread(s)
Quoted: 7957 Post(s)
Originally Posted by justin1138 View Post
Similar weight and tire set up, I have my pressure around 35#'s. The front is usually 1-2#'s lower than the rear.

I like to feel it out in the yard a day or two before racing (so there's no surprises), and add/subtract pressure so there's not too much rim hitting the ground.
Ok good to know. Yea the first race of the season I had the back at 35psi...and only noticed what I think was a foldover once, and it was on a very slight off camber that I took pretty hard. Then the next race I had it at 30...and it seemed I had that sensation on pretty much every corner I took hard.
Abe_Froman is offline  
Reply With Quote
Old 09-27-18, 06:27 AM
  #8  
Jakedatc
Senior Member
 
Jakedatc's Avatar
 
Join Date: Oct 2007
Location: CT
Posts: 2,990
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Originally Posted by Abe_Froman View Post
Sorry. I'm 190lbs, on 35mm all purpose cross tires. No idea what the rating is...but I really doubt that makes any difference.

Thinking of getting a set of Compass Steilacoom tires and running them tubeless....but just worrying about tubed setup right now.
Check out some Donnelly BOS or PDX if you want a good chunky CX tire for tubeless. https://www.probikekit.com/bicycle-t.../11651868.html

I also run 25ish on tubeless (125lb)
Jakedatc is offline  
Reply With Quote
Old 09-27-18, 10:54 AM
  #9  
redlude97
Senior Member
 
Join Date: Sep 2011
Posts: 3,620
Mentioned: 18 Post(s)
Tagged: 0 Thread(s)
Quoted: 1392 Post(s)
I generally check my pressures during the course previews by lowering it until they bottom out on the roughest sections and then adding back a few psi. Since you are running tubed that may not be an option. A good amount of squirm is normal though and you just get used to it if you are coming from a mostly road background
redlude97 is offline  
Reply With Quote
Old 09-27-18, 11:05 AM
  #10  
Abe_Froman
Senior Member
Thread Starter
 
Abe_Froman's Avatar
 
Join Date: Aug 2016
Location: Chicago
Posts: 2,286

Bikes: Marin Four Corners, 1960's Schwinn Racer in middle of restoration, mid 70s Motobecane Grand Touring, various other heaps.

Mentioned: 43 Post(s)
Tagged: 0 Thread(s)
Quoted: 7957 Post(s)
Originally Posted by redlude97 View Post
I generally check my pressures during the course previews by lowering it until they bottom out on the roughest sections and then adding back a few psi. Since you are running tubed that may not be an option. A good amount of squirm is normal though and you just get used to it if you are coming from a mostly road background
Well the squirm didnt phase me at all. But the tire folding completely over, the rim sliding sideways across it and onto the ground was a bit disconcerting lol.
Abe_Froman is offline  
Reply With Quote
Old 10-04-18, 10:45 AM
  #11  
50voltphantom
Senior Member
 
50voltphantom's Avatar
 
Join Date: Feb 2014
Location: SD
Posts: 2,574

Bikes: Surly Steamroller, Handsome Fredward

Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 426 Post(s)
Originally Posted by Abe_Froman View Post
Well the squirm didnt phase me at all. But the tire folding completely over, the rim sliding sideways across it and onto the ground was a bit disconcerting lol.
More then. If it's affecting your line choice, adjustment is needed.
50voltphantom is offline  
Reply With Quote
Old 10-05-18, 08:15 AM
  #12  
Abe_Froman
Senior Member
Thread Starter
 
Abe_Froman's Avatar
 
Join Date: Aug 2016
Location: Chicago
Posts: 2,286

Bikes: Marin Four Corners, 1960's Schwinn Racer in middle of restoration, mid 70s Motobecane Grand Touring, various other heaps.

Mentioned: 43 Post(s)
Tagged: 0 Thread(s)
Quoted: 7957 Post(s)
Originally Posted by 50voltphantom View Post
More then. If it's affecting your line choice, adjustment is needed.
Yea. I've tried it at 34/36...feels much better.
Abe_Froman is offline  
Reply With Quote

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