Tire Presure
#1
Senior Member
Thread Starter
Join Date: Aug 2014
Location: Weston, Fl
Posts: 72
Bikes: 1988 Trex 360, 1975 Fugi Special Road Racer (turned fixie), 2012 Felt Nine Trail
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Tire Presure
Found the link below and was wondering what your thoughts are. My bike and I weigh 195 lbs (on 25c) and based on using the Race Bike ratio, my front tire should be around 67 psi (seems really low). What do you think?
https://www.bikequarterly.com/images/TireDrop.pdf
https://www.bikequarterly.com/images/TireDrop.pdf
#3
Banned.
Join Date: Sep 2014
Posts: 790
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Try 95 to 105 psi, depends on the tire.
Above 90 degree you can go a little higher psi.
U want some tire deflection or it will be like sitting on a bench grinder ...
Above 90 degree you can go a little higher psi.
U want some tire deflection or it will be like sitting on a bench grinder ...
#4
Senior Member
Join Date: Aug 2014
Posts: 360
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I am lighter (175lbs) but regularly run 70 psi in my front tire (25mm) and even lower in a 28mm. I don't see much deflection in the tire and have yet to run into any issues.
#5
Senior Member
Join Date: Jan 2011
Location: Pinehurst, NC, US
Posts: 1,716
Bikes: 2020 Trek Emonda SL6, 90's Vintage EL-OS Steel Bianchi with 2014 Campy Chorus Upgrade
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 452 Post(s)
Liked 162 Times
in
110 Posts
What is interesting in this report is the front vs. rear suggestion. Use the road bike sample (40/60 load front/back), you would end up running tire pressures in the back around 50% higher than in the front. I doubt that many folks do that.
dave
dave
#6
Senior Member
Join Date: Jul 2008
Location: Minas Ithil
Posts: 9,173
Mentioned: 66 Post(s)
Tagged: 0 Thread(s)
Quoted: 2432 Post(s)
Liked 638 Times
in
395 Posts
I run about 10psi higher on the front than this chart shows just so it's not too squishy when sprinting and climbing. My rear pressure is pretty much what the chart recommends.
https://www.crw.org/safety/12safetyPg...v-pressure.php
https://www.crw.org/safety/12safetyPg...v-pressure.php
#7
Should Be More Popular
Join Date: Dec 2007
Location: Malvern, PA (20 miles West of Philly)
Posts: 43,045
Bikes: 1986 Alpine (steel road bike), 2009 Ti Habenero, 2013 Specialized Roubaix
Mentioned: 560 Post(s)
Tagged: 2 Thread(s)
Quoted: 22590 Post(s)
Liked 8,924 Times
in
4,157 Posts
#9
Advocatus Diaboli
Join Date: Feb 2015
Location: Wherever I am
Posts: 8,635
Bikes: Merlin Cyrene, Nashbar steel CX
Mentioned: 14 Post(s)
Tagged: 1 Thread(s)
Quoted: 4733 Post(s)
Liked 1,531 Times
in
1,002 Posts
Yeah, personally I would probably defer to keeping the inflation within the specifications of the tire manufacturers even if the deflection guides suggest lower PSIs are 'optimal' -- simply because there's no way a pinch-flatted tire resulting from underinflation would exhibit better performance than using a 'sub-optimal' pressure that increases likelihood of preventing a pinch flat. Eg. Michelin doesn't recommend below 87psi or over 116psi on its road tires, no matter the weight.. Of course there's likely some margin of safety on both ends of the scale, but I wouldn't probably extend more than another 10psi either way. Tire Pressures - How to fit (Video) | Welcome to MICHELIN Bicycle - North America
(BTW, the below link has a couple options that do similar calculations) to your linked article
Bicycle tire pressure calculator
(BTW, the below link has a couple options that do similar calculations) to your linked article
Bicycle tire pressure calculator
#10
working on my sandal tan
Join Date: Aug 2011
Location: CID
Posts: 22,629
Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)
Mentioned: 98 Post(s)
Tagged: 0 Thread(s)
Quoted: 3871 Post(s)
Liked 2,568 Times
in
1,579 Posts
Found the link below and was wondering what your thoughts are. My bike and I weigh 195 lbs (on 25c) and based on using the Race Bike ratio, my front tire should be around 67 psi (seems really low). What do you think?
https://www.bikequarterly.com/images/TireDrop.pdf
https://www.bikequarterly.com/images/TireDrop.pdf
I think it's better to stick to 45%/55% for road bikes. That's enough to get you more hand comfort and pinch flat protection in the rear. After maybe 5 years doing it, I've had no pinch flats whatsoever with the calculated tire pressures. Concerns about increased rolling resistance went away when I noticed that I actually felt fresher after long rides, rather than being "beat up".
Here's what I use for a total weight of 190-200 lbs, listed as front/rear:
28mm: 65/80psi
30mm: 60/70psi
37mm: 40/50psi
42mm: 32.5/40psi
#12
Senior Member
Join Date: Feb 2006
Posts: 524
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 34 Post(s)
Likes: 0
Liked 17 Times
in
13 Posts
You're supposed to weigh yourself fully dressed to ride, and the bike fully equipped to ride. I weigh 145 lb. and my bike weighs 20.5 lb, but when dressed to ride with water bottle etc. on the bike and using a 40%/60% split between front and rear wheels, the chart says I should use 110 psi in back and 75 in front for 700cx23 tires.
Ideally you're supposed to actually find out what you and your bike weigh on a scale by putting the scale under each wheel (and a support under the other to keep everything level) and then look up the pressure on the chart.
If I remember correctly, the article mentions that if the recommended pressure is too low, use a narrower tire; if too high, use a wider tire.
I converted the chart into a calculator that you plug numbers into and it tells you the matching psi values from the chart. It also offers the numbers from Michelin Bicycle Tires weight-based chart for 700c tires as an alternative.
Ideally you're supposed to actually find out what you and your bike weigh on a scale by putting the scale under each wheel (and a support under the other to keep everything level) and then look up the pressure on the chart.
If I remember correctly, the article mentions that if the recommended pressure is too low, use a narrower tire; if too high, use a wider tire.
I converted the chart into a calculator that you plug numbers into and it tells you the matching psi values from the chart. It also offers the numbers from Michelin Bicycle Tires weight-based chart for 700c tires as an alternative.
#13
Senior Member
Join Date: Mar 2012
Location: Lund, Sweden
Posts: 323
Bikes: Ridley Noah, Trek Emonda, Colnago C59, Colnago Master, 1980 Colnago Super, Wilier Blade
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
I weigh 150lbs and have I been using the charts recommendations for the last three years on my 25 and 28 mm Conti GP4000 tires. The ride is more comfortable, I have stopped looking for better saddles, the wear on the tires is more even, not a narrow center strip that wears through first and I get about one flat per year. No change in performance, on the contrary on rough tarmac I think the lower inflation rolls much better. I would however recommend actually weighing your weight on the front and rear tire, since I am closer to 45/55 as well. I have 3 different wheel sets and never had any problem with the lower pressures, even on high speed descents in the Alps with lots of hair pin turns.
#14
Administrator
Join Date: Feb 2005
Location: Delaware shore
Posts: 13,558
Bikes: Cervelo C5, Guru Photon, Waterford, Specialized CX
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1106 Post(s)
Liked 2,173 Times
in
1,464 Posts
These charts are primarily for touring. Note most say "gear" with riders weight. A touring bike, especially loaded, handles a lot differently than a racing style.
#15
Senior Member
Thread Starter
Join Date: Aug 2014
Location: Weston, Fl
Posts: 72
Bikes: 1988 Trex 360, 1975 Fugi Special Road Racer (turned fixie), 2012 Felt Nine Trail
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Today I used the recommended psi and I was just as fast but with the added benefit of extra smoothness. This is something I'm always seeking because I ride an aluminum frame. I thought the 70psi on the front was going to be too low but it actually feels right. I've found my new tire pressures (R-105 & F-70), for now.
#16
Senior Member
Today I used the recommended psi and I was just as fast but with the added benefit of extra smoothness. This is something I'm always seeking because I ride an aluminum frame. I thought the 70psi on the front was going to be too low but it actually feels right. I've found my new tire pressures (R-105 & F-70), for now.
#17
Senior Member
Join Date: Jun 2013
Location: SW Fl.
Posts: 5,617
Bikes: Day6 Semi Recumbent "FIREBALL", 1981 Custom Touring Paramount, 1983 Road Paramount, 2013 Giant Propel Advanced SL3, 2018 Specialized Red Roubaix Expert mech., 2002 Magna 7sp hybrid, 1976 Bassett Racing 45sp Cruiser
Mentioned: 18 Post(s)
Tagged: 0 Thread(s)
Quoted: 1068 Post(s)
Liked 781 Times
in
503 Posts
Scale under front tire, scale under rear tire, balance in a doorway with one hand on door frame other on bars and a good weight/wheel is the result.
#19
On Your Left
Join Date: Nov 2011
Location: Long Island, New York, USA
Posts: 8,373
Bikes: Trek Emonda SLR, Sram eTap, Zipp 303
Mentioned: 34 Post(s)
Tagged: 0 Thread(s)
Quoted: 3004 Post(s)
Liked 2,433 Times
in
1,187 Posts
I ride Continental GP4000SII 25mm with 100/110.
I've ridden with lower pressure and find the bike sluggish and squishy.
I'm 200# and the bike is 14#
I've ridden with lower pressure and find the bike sluggish and squishy.
I'm 200# and the bike is 14#
Last edited by GlennR; 05-31-15 at 08:28 PM.
#21
Senior Member
Join Date: Jan 2011
Location: Pacific NW
Posts: 563
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
remember 25mm and larger tires are oy faster when at equal preassures running lower pressure increases the deflection/contact patch further.
Only comfort bikes and beach cruisers run low pressure
#22
Senior Member
Join Date: Mar 2012
Location: Tallahassee, FL
Posts: 4,811
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1591 Post(s)
Likes: 0
Liked 1,018 Times
in
571 Posts
I run 110 - 115 front and rear on 25mm and weigh about 145. I prefer a firm ride and anything under 100 would feel way too soft.
#23
Senior Member
Many studies have show that slightly lower tire pressures produce a faster ride ... less deflection and rebound.
#25
Senior Member
Join Date: Dec 2009
Location: Houston, TX
Posts: 28,682
Bikes: 1990 Romic Reynolds 531 custom build, Merlin Works CR Ti custom build, super light Workswell 066 custom build
Mentioned: 109 Post(s)
Tagged: 1 Thread(s)
Quoted: 6556 Post(s)
Likes: 0
Liked 58 Times
in
36 Posts
Yes but during braking the effective mass shifts forward so it is wise to over fill the front slightly relative to the result you get from your measurement.