Go Back  Bike Forums > Bike Forums > Mountain Biking
Reload this Page >

Front Rear Tire differential

Mountain Biking Mountain biking is one of the fastest growing sports in the world. Check out this forum to discuss the latest tips, tricks, gear and equipment in the world of mountain biking.

Front Rear Tire differential

Old 04-12-19, 04:34 PM
  #1  
SoldSpartan
Senior Member
Thread Starter
 
Join Date: Jul 2018
Location: Hoschton GA
Posts: 53
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 18 Post(s)
Front Rear Tire differential

So the front and rear tires on my mountain bike are made from two different manufactures and the front tire says to keep the tire pressure between 26psi-54psi. The rear tire says to keep it between 30psi and 45psi. So I figure to keep the front and rear tires at 30psi; is this the right idea?
SoldSpartan is offline  
Old 04-12-19, 04:42 PM
  #2  
79pmooney
A Roadie Forever
 
79pmooney's Avatar
 
Join Date: Oct 2014
Location: Portland, OR
Posts: 6,569

Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder

Mentioned: 88 Post(s)
Tagged: 0 Thread(s)
Quoted: 1502 Post(s)
Keep the tires below that maximum and with enough air to keep from pinch flatting. The minimums on the tire are just suggestions. Are the tires the same size? Are they similar type? If not, play with the pressure until they feel right. In general, a little less air in front works out best since you put less weight on the front. I generally use 5-8 psi less in front if the tires are the same size and type.

Ben
79pmooney is online now  
Old 04-13-19, 09:59 PM
  #3  
enveous
Member
 
Join Date: Apr 2019
Posts: 45
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
Not enough information.

Optimal tire pressure will depend on:

Tubed or tubeless
Tire size
Casing type
Rim width
Rider weight
Terrain
Aggressiveness of the rider
enveous is offline  
Old 04-15-19, 09:10 AM
  #4  
prj71
Senior Member
 
Join Date: Jun 2015
Posts: 1,575
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 862 Post(s)
30 psi is a little high for mountain bike use. ~25 is more reasonable for single track riding.
prj71 is offline  
Old 04-15-19, 09:20 AM
  #5  
enveous
Member
 
Join Date: Apr 2019
Posts: 45
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
Originally Posted by prj71 View Post
30 psi is a little high for mountain bike use. ~25 is more reasonable for single track riding.
How much does the OP weigh?
What tires are they using (size, casing, tubes/tubeless)?
What rims?
Are they riding buff singletrack at mellow speeds or charging nonstop chunk?
Do they "ride light" or are they proverbial bull in a china shop?

Depending on the answers to those questions, ~25 psi may or may not be reasonable.
enveous is offline  
Old 04-15-19, 09:29 AM
  #6  
rumrunn6
Senior Member
 
rumrunn6's Avatar
 
Join Date: Jul 2008
Location: 25 miles northwest of Boston
Posts: 22,307

Bikes: Bottecchia Sprint, GT Timberline 29r

Mentioned: 78 Post(s)
Tagged: 0 Thread(s)
Quoted: 2856 Post(s)
exact #s aside, maybe squeeze them with your eyes closed? the front should feel softer. I like to look at the rear tire as I roll, to see how much it is deforming under my weight. I don't want a pinch flat but I also want some strength & weight bearing. plus if the trail is a harder pack variety I can go a little faster if the rear is a little harder than what I would use on softer ground. it's been surprising for me to see how low I can ride w tubed 29x2.25 Riddlers. I think they're at 21 front 25 rear
rumrunn6 is offline  
Old 04-15-19, 01:19 PM
  #7  
hig4s
Senior Member
 
hig4s's Avatar
 
Join Date: Jul 2015
Location: Florida
Posts: 646

Bikes: Evil Insurgent, Giant Stance, Wife has Liv Cypress, son has Motobecane HT529

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 86 Post(s)
For best traction on technical and soft surfaces I usually keep lowering my tire pressure until they either start feeling squirmy on the corners, or start getting pinch flats on obstacles. I run Maxxis Ardents on one bike and Maxxis Minions on the other, both with tubes. For me this ends up being 20 to 22psi front and 25 to 28psi rear.
hig4s is offline  
Old 04-16-19, 08:42 AM
  #8  
prj71
Senior Member
 
Join Date: Jun 2015
Posts: 1,575
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 862 Post(s)
Originally Posted by enveous View Post
How much does the OP weigh?
What tires are they using (size, casing, tubes/tubeless)?
What rims?
Are they riding buff singletrack at mellow speeds or charging nonstop chunk?
Do they "ride light" or are they proverbial bull in a china shop?

Depending on the answers to those questions, ~25 psi may or may not be reasonable.
There is no magic number, but ~25 psi works well in most cases for most people. 30 psi is too high.
prj71 is offline  
Old 04-16-19, 10:32 AM
  #9  
enveous
Member
 
Join Date: Apr 2019
Posts: 45
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
Originally Posted by prj71 View Post
There is no magic number, but ~25 psi works well in most cases for most people. 30 psi is too high.
So when I ran 32f/35r psi in 2.3 Kujos, with DH casings, tubed, mounted on Mavic 317s they were too high? Why did I double pinch flat then? Why did I get tire flop at lower pressures?

Here's my buddy riding 30 psi on his Knolly, why is 30 psi too high for him? He's run lower but had issues with squirm and flatting.


Again, there are many variables that come in to play when getting to the right pressure. Variables that you either don't understand or choose to ignore.




enveous is offline  
Old 04-16-19, 11:55 AM
  #10  
prj71
Senior Member
 
Join Date: Jun 2015
Posts: 1,575
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 862 Post(s)
Do you know the difference between a general recommendation and hard and fast rules?
prj71 is offline  
Old 04-16-19, 12:16 PM
  #11  
enveous
Member
 
Join Date: Apr 2019
Posts: 45
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
Originally Posted by prj71 View Post
Do you know the difference between a general recommendation and hard and fast rules?
Yes, and "30 psi is too high" is a specific recommendation,

Here are some general recommendations-

"Optimal tire pressure will depend on:

Tubed or tubeless
Tire size
Casing type
Rim width
Rider weight
Terrain
Aggressiveness of the rider"
enveous is offline  
Old 04-17-19, 08:39 AM
  #12  
prj71
Senior Member
 
Join Date: Jun 2015
Posts: 1,575
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 862 Post(s)
Ugh. You are obtuse. I'm not denying all of that comes into play. Those are hard and fast recommendations for the biker that is a tire geek.

For the general public that doesn't want to deal with figuring all of that out...25 psi is a good safe number for traction and rolling resistance. Assuming we aren't talking about a 300 lb rider.

And generally speaking 30 psi is too high. Especially on a hard tail as it would be like riding a bucking bronco.

Last edited by prj71; 04-17-19 at 08:50 AM.
prj71 is offline  
Old 04-17-19, 09:05 AM
  #13  
enveous
Member
 
Join Date: Apr 2019
Posts: 45
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
Originally Posted by prj71 View Post
And generally speaking 30 psi is too high. Especially on a hard tail as it would be like riding a bucking bronco.
Nah. It depends.

For example:

The rigid bike in the video above is running 40f/45r which are good pressures for a 175 pound rider running 40mm tires on tubeless i25 rims on that trail. On the same trail (below, starting at 0:14), 18f/20r are good pressures ona FS bike when running 2.5 tires with reinforced casings on i35 rims.


"Optimal tire pressure will depend on:

Tubed or tubeless
Tire size
Casing type
Rim width
Rider weight
Terrain
Aggressiveness of the rider"

Last edited by enveous; 04-17-19 at 09:17 AM.
enveous is offline  
Old 04-17-19, 05:20 PM
  #14  
Bigbus
Senior Member
 
Bigbus's Avatar
 
Join Date: Mar 2018
Location: Central West Coast
Posts: 220

Bikes: In Flux

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 56 Post(s)
I've never had the same tire on the front and rear of any of my bikes at the same time. Is that even possible?
Seriously, I usually run a slightly wider and softer (less pressure) tire on the front and a more aggressive and heavier tire on the rear. Everyone has their own preferences and what works for them may not work for all.
Bigbus is offline  

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.