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Tyre pressures

  • 19-01-2021 12:41pm
    #1
    Registered Users Posts: 2,635 ✭✭✭ triggermortis


    Anybody looked into this at all?

    I was watching a video in work there and it mentioned this link for optimal tyre pressures:

    https://axs.sram.com/guides/tire/pressure

    I just usually pump mine to around 100psi to avoid pinch flats and that seems to do the trick. I definitely don't lower the pressures when it's wet and I put the same pressure in both tyres.
    I think it's time to experiment...


Comments

  • Registered Users Posts: 9,775 ✭✭✭ Effects


    Think there was a thread about it a while back. I run 28mm at 90 front and back generally.


  • Moderators, Sports Moderators Posts: 22,111 Mod ✭✭✭✭ CramCycle


    There are benefits for different scenarios but the hassle of it unless it is for safety reasons isn't worth it IMO. I have only bothered lowering it for CX races and that's it. Around 100psi maybe a little less for me, front and back.


  • Registered Users Posts: 5,510 ✭✭✭ secman


    100 psi for me on 25's as Cram says too much hassle otherwise


  • Registered Users Posts: 187 ✭✭ rayman1


    Used to run at 100 psi but changed about 5 years ago and now I run my 25mm tyres at 85psi and never had an issue with pinch flats. It is dependent on weight and size of tyre and there are formulas online. I weigh 70kg.
    Have a look at this video from GCN https://m.youtube.com/watch?v=4sDX54zNmxY


  • Moderators, Recreation & Hobbies Moderators Posts: 18,625 Mod ✭✭✭✭ Brian?


    I just bought new tyres. 25mm wide

    The recommended pressure is 115psi to 145psi.

    This is madness.

    they/them/theirs


    And so on, and so on …. - Slavoj Žižek




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  • Moderators, Sports Moderators Posts: 22,111 Mod ✭✭✭✭ CramCycle


    Brian? wrote: »
    I just bought new tyres. 25mm wide

    The recommended pressure is 115psi to 145psi.

    This is madness.

    That doesn't sound right, are you sure that's just not the max pressure? What tyres are they?


  • Registered Users Posts: 6,641 ✭✭✭ cletus


    Could be max pressure. Mate of mine has a mountain bike with 2.something wide tyres, he was running them at 80psi, which was the max pressure on the sidewall


  • Moderators, Recreation & Hobbies Moderators Posts: 18,625 Mod ✭✭✭✭ Brian?


    CramCycle wrote: »
    That doesn't sound right, are you sure that's just not the max pressure? What tyres are they?

    I got quite the shock myself.

    It says min pressure 115 psi, max pressure 145 psi. I've had road bikes since the late 80s and never seen the likes of it.

    they/them/theirs


    And so on, and so on …. - Slavoj Žižek




  • Moderators, Recreation & Hobbies Moderators Posts: 18,625 Mod ✭✭✭✭ Brian?


    Picture attached. I understand the incredulity.

    Edit: this is the tyre

    https://www.futurumshop.nl/vredestein-fortezza-senso-superiore-all-weather-vouwband-geel-zwart.phtml

    they/them/theirs


    And so on, and so on …. - Slavoj Žižek




  • Registered Users Posts: 24,669 ✭✭✭✭ Wishbone Ash


    Brian? wrote: »
    Picture attached. I understand the incredulity.

    Edit: this is the tyre

    https://www.futurumshop.nl/vredestein-fortezza-senso-superiore-all-weather-vouwband-geel-zwart.phtml
    I wouldn't trust my rims at that pressure. :eek:

    (Just looking at the reviews on Wiggle - they get an average 5 out of 5 on 102 reviews. That's pretty impressive).


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  • Moderators, Recreation & Hobbies Moderators Posts: 18,625 Mod ✭✭✭✭ Brian?


    I wouldn't trust my rims at that pressure. :eek:

    (Just looking at the reviews on Wiggle - they get an average 5 out of 5 on 102 reviews. That's pretty impressive).

    I’m going to run them at 115psi on my commute tomorrow. Normally I run 25s at 100. There’s a couple of city pavé sections on my way in. It’s going to be interesting.

    The tyres get great reviews everywhere which is why I bought them, aside from the silliness of wanting tan sidewall tyres on my bike. It’s a 90s steel bike, so I want so retro.

    they/them/theirs


    And so on, and so on …. - Slavoj Žižek




  • Registered Users Posts: 1,003 ✭✭✭ route66




    SNIP

    optimal tyre pressures:


    SNIP


    Here is a graph I have used in the past to determine optimal tyre pressures - it's not mine, but was mentioned here in the past:


    541357.jpg


  • Moderators, Sports Moderators Posts: 22,111 Mod ✭✭✭✭ CramCycle


    Brian? wrote: »
    I’m going to run them at 115psi on my commute tomorrow. Normally I run 25s at 100. There’s a couple of city pavé sections on my way in. It’s going to be interesting.

    and?


  • Moderators, Sports Moderators Posts: 42,444 Mod ✭✭✭✭ magicbastarder


    i was in a bike shop in dublin a couple of years ago where one of the sales guys told me he ran his tyres at 140psi on his commuting bike and insisted his commute (on suburban roads) was noticeably faster as a result. which made me a little suspicious of the waxing lyrical he was doing about the wheels he was trying to sell me.


  • Moderators, Sports Moderators Posts: 22,111 Mod ✭✭✭✭ CramCycle


    To be fair, that was the thinking and in my own opinion, it certainly feels faster but as everyone now knows when you look at Strava (and other more scientific analysis) it's not true, but it does feel it.


  • Moderators, Sports Moderators Posts: 42,444 Mod ✭✭✭✭ magicbastarder


    140psi may be fine on well paved spanish roads, but a commute to santry on 140psi must be uncomfortable.


  • Moderators, Recreation & Hobbies Moderators Posts: 18,625 Mod ✭✭✭✭ Brian?


    CramCycle wrote: »
    and?

    Lovely. Rolled very well. Minimal bounciness.

    I even came home via extra cobbles to check and was pleasantly surprised. Going to up the pressure to 120, then 130 to see.

    they/them/theirs


    And so on, and so on …. - Slavoj Žižek




  • Registered Users Posts: 4,218 ✭✭✭ Daroxtar


    My carbon wheels (Campag Bora) have a max pressure of 120psi so I guess I won't be fitting those tyres :D
    Same as previous posters, I'm running 25s at roughly 100psi on both carbon and aluminium wheels. I've run them at 90, no bother there and slightly more comfy but below that I'm just a bit cautious of pinch flats.


  • Registered Users Posts: 7,389 ✭✭✭ 54and56


    route66 wrote: »
    Here is a graph I have used in the past to determine optimal tyre pressures - it's not mine, but was mentioned here in the past:


    541357.jpg

    Here's a handy app for calculating based on Frank Berto's formula. You can save different bikes / bike setups for quick reference including front and back loads in addition to the rider etc.

    Free / limited version - https://play.google.com/store/apps/details?id=com.edisongauss.bertotirepressure.demo&hl=en

    Paid €2.50 customisable version - https://play.google.com/store/apps/details?id=com.edisongauss.bertotirepressure&hl=en


  • Registered Users Posts: 9,894 ✭✭✭ Canis Lupus


    Brian? wrote: »
    Lovely. Rolled very well. Minimal bounciness.

    I even came home via extra cobbles to check and was pleasantly surprised. Going to up the pressure to 120, then 130 to see.

    I assume the rims are rated for 130. My stock giant pr2s are rated for 125 only. Just something to check hey.


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  • Registered Users Posts: 11,592 ✭✭✭✭ tomasrojo


    I just go for the lower end or middle of the range quoted on the side wall. Which is 6 bar for 700x28s and Brompton tyres and 5 bar on just about everything else (kids' bikes, cargo bike). I've tried higher and I don't really see any difference, but it would have to be very big difference for me to notice. Not using any of the bikes for anything competitive.


  • Moderators, Recreation & Hobbies Moderators Posts: 18,625 Mod ✭✭✭✭ Brian?


    I assume the rims are rated for 130. My stock giant pr2s are rated for 125 only. Just something to check hey.

    Mavic Aksiums are rated at 135, so I think I'll take it handy.

    I had to bring 35 macaroons to work today so I stuck with 115. Didn't want to lose any

    they/them/theirs


    And so on, and so on …. - Slavoj Žižek




  • Registered Users Posts: 1,001 ✭✭✭ Large bottle small glass


    Have my H plus son archetype wheels with 28mm gp4000 back on bike.

    Checked pressure when I came home. Just over 3bar(just under 50psi) front and rear.

    1 HR spin on back roads with variable surfaces. It was lovely.

    The 28mm are effectively 31mm or so but still below the 4.5bar or so recommended for a 45/50kg wheel load.

    Have them set to 4 bar(60psi) for tomorrow which is where they normally are.

    One pinch flat on a forest road last summer in over 20k km of my current set up


  • Moderators, Sports Moderators Posts: 13,438 Mod ✭✭✭✭ ednwireland


    about 85 for my 28mm tyres


  • Registered Users Posts: 2,700 ✭✭✭ Type 17


    Total weight is just under 100kg (me and the bike) and I run 28's and use 90 in the back and 85 in the front - never had any pinches or issues, even after hitting potholes hard on descents.
    I used to run 100/100, but suffered from sore bum and wrists after about an hour.
    For a while I tried 85 rear & 75 front, and still never had a pinch, but found tyre wear to be an issue (they were soft/light/fragile tyres, but I think that they'd have lasted better at 90/85).


  • Moderators, Society & Culture Moderators Posts: 15,358 Mod ✭✭✭✭ smacl


    32c gravelking slicks at 50/60 front/back for me. Was running a bit lower but got a pinch flat last week. Tend to run a bit higher pressure if I know I'm not going off road and a bit lower if i am. Definitely feels a bit faster on road with higher pressure.


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