Road Bike, Cycling Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
121 Posts
Discussion Starter · #1 ·
Have always wondered about ideal air pressure. Recently I put new tires on (Vredestein Fortezzas). They have a max rating of 175 psi. Now that seems a little rediculous to me, but ok. So here's the question: For a 185 pounder with tires rated at 175 psi max, what would be the ideal air pressure to obtain the least rolling resistance. How much air do I need to go the fastest? I have heard from friends that anything over around 125 lbs psi causes the tire to roll slower? Is this true?

Is there so kind of formula to figure it out?

Thanks,

Mike
 

·
Registered
Joined
·
890 Posts
At your weight, I'd go for ~100.

I weight about 10 lbs less, and I ride my tires right around that. Even 115 might throw you around a bit. Doesn't really matter what a tire is rated at, it most likely won't ride very well at that highest level rating.
 

·
Banned
Joined
·
16,915 Posts
tanner3155 said:
Have always wondered about ideal air pressure. Recently I put new tires on (Vredestein Fortezzas). They have a max rating of 175 psi. Now that seems a little rediculous to me, but ok. So here's the question: For a 185 pounder with tires rated at 175 psi max, what would be the ideal air pressure to obtain the least rolling resistance. How much air do I need to go the fastest? I have heard from friends that anything over around 125 lbs psi causes the tire to roll slower? Is this true?

Is there so kind of formula to figure it out?

Thanks,

Mike
No formula but test data:

http://www.slowtwitch.com/Tech/What_s_in_a_tube__1034.html
 

·
Registered
Joined
·
134 Posts
For 185lbs, 100psi might feel rather squishy, but whatever, it depends on the roads. If you roll over anything that comes close to a sharp knock on the wheel, it's a pinch flat waiting to happen. For rough chip-seal, you might like it, but for smooth tarmac, 120 is perfectly fine.
I weigh 135lbs, and never go under 100 except for the roughest ashphalt. Ride lots at different pressures, and see what you like!
 

·
eRacer
Joined
·
2,555 Posts
I weigh 185/7 and run Michelin 700x23 Tires at 110-Rear, and 100-Front.
Nice roll, no pinch flats and certainly not squishy.
I use the graph for 15% tire depression to arrive at these values, and they have served me well for years.

john
 

·
Banned
Joined
·
605 Posts
jmlapoint said:
I weigh 185/7 and run Michelin 700x23 Tires at 110-Rear, and 100-Front.
Nice roll, no pinch flats and certainly not squishy.
I use the graph for 15% tire depression to arrive at these values, and they have served me well for years.

john
After much back and forth that is where I ended up and I'm 163
 

·
Registered
Joined
·
472 Posts
I have used Vredstein Fortezzas (700x23 and 25s) for many years and ride them at 100 front & back - I weigh about 175lbs - with no issues on flats, etc.
 

·
Registered
Joined
·
21,542 Posts
Rolling resistance

tanner3155 said:
=I have heard from friends that anything over around 125 lbs psi causes the tire to roll slower? Is this true?
When your tires are over-inflated, they will bounce off of road surface imperfections rather than conform to them. That "bounce energy" goes into your body and is lost. This is the reason that high pressures can be slower (depending on road surface and rider weight). Beyond that, high pressure means poor traction, faster wear, and loss of comfort. Agreeing with everyone else: 100-110 psi (7-7.5 bar) is the right range for your rear tire (assuming 23mm width).
 
1 - 11 of 11 Posts
Top