Archetype/25c tyre pressure?

kingofthetailwind
kingofthetailwind Posts: 575
edited March 2014 in Workshop
With the dry weather it's finally time to take my new TCR out. :D Fitted my new H Plus Son Archetypes and 25c Michelin pro4 Service Course tyres last week.

I've read that you should use lower pressure with 25mm rims like the Archetype. And of course you can use lower pressure using 25c tyres. (I've used 23c up to now at about 115/110) So how low should I go with the new bike? I'm 76kg.

Comments

  • drlodge
    drlodge Posts: 4,826
    I pump my 25c tyres up to about 110psi. That might be a bit high, I pump 23c up to around 120psi
    WyndyMilla Massive Attack | Rourke 953 | Condor Italia 531 Pro | Boardman CX Pro | DT Swiss RR440 Tubeless Wheels
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  • giant_man
    giant_man Posts: 6,878
    for 23C or 25C tyres, I usually put 100/110psi.
  • ugo.santalucia
    ugo.santalucia Posts: 28,312
    You guys are crazy... ninety is plenty
    left the forum March 2023
  • jp1970
    jp1970 Posts: 134
    ugo.santalucia wrote:
    You guys are crazy... ninety is plenty
    ^ + 1
  • rafletcher
    rafletcher Posts: 1,235
    ugo.santalucia wrote:
    You guys are crazy... ninety is plenty

    Wouldn't it depend on the recommended minimum pressure for the tyre? For the michelins that'll probably be 6 bar but for my veloflex it's 7 bar ( or 100 psi)
  • ugo.santalucia
    ugo.santalucia Posts: 28,312
    rafletcher wrote:
    ugo.santalucia wrote:
    You guys are crazy... ninety is plenty

    Wouldn't it depend on the recommended minimum pressure for the tyre? For the michelins that'll probably be 6 bar but for my veloflex it's 7 bar ( or 100 psi)

    I've never given much thought about minimum pressure... some CX clinchers have 60 PSI minimum but people use them at 25 PSI...
    Vittoria CX 27 tubs have 5-8 bars, I use them at 4.5, I use CX 23 tubs at 100 PSI, which I believe is lower than the minimum... never had problems with low pressure
    left the forum March 2023
  • Moonbiker
    Moonbiker Posts: 1,706
    Do you only weigh 60kg?

    25psi would it really be bulging out as it rolls?
  • ugo.santalucia
    ugo.santalucia Posts: 28,312
    Moonbiker wrote:
    Do you only weigh 60kg?

    25psi would it really be bulging out as it rolls?

    That's what CX people do for racing 32 and 37 mm tyres in muddy conditions, successfully... I don't race... I have used them at 40 PSI, not lower
    left the forum March 2023
  • Wirral_paul
    Wirral_paul Posts: 2,476
    I'm heavier than the OP and run 90psi rear and 85psi front with the same rims and Pro4 Endurance 25mm........ and it still feels like i'd be better off going lower. Gonna try 85/80 next.
  • kingofthetailwind
    kingofthetailwind Posts: 575
    OK, thanks for the advice guys. I think I'm going to go 95 rear 90 front initially, and lower if needed.
  • littledove44
    littledove44 Posts: 871
    “Tire Width=20: Pressure(psi) = (0.33 * Rider Weight in lbs) + 63.33
    Tire Width=23: Pressure(psi) = (0.33 * Rider Weight in lbs) + 53.33
    Tire Width=25: Pressure(psi) = (0.33 * Rider Weight in lbs) + 43.33
    Tire Width=28: Pressure(psi) = (0.33 * Rider Weight in lbs) + 33.33
    Tire Width=32: Pressure(psi) = (0.17 * Rider Weight in lbs) + 41.67
    Tire Width=37: Pressure(psi) = (0.17 * Rider Weight in lbs) + 26.67
  • keef66
    keef66 Posts: 13,123
    littledove44 wrote:
    “Tire Width=20: Pressure(psi) = (0.33 * Rider Weight in lbs) + 63.33
    Tire Width=23: Pressure(psi) = (0.33 * Rider Weight in lbs) + 53.33
    Tire Width=25: Pressure(psi) = (0.33 * Rider Weight in lbs) + 43.33
    Tire Width=28: Pressure(psi) = (0.33 * Rider Weight in lbs) + 33.33
    Tire Width=32: Pressure(psi) = (0.17 * Rider Weight in lbs) + 41.67
    Tire Width=37: Pressure(psi) = (0.17 * Rider Weight in lbs) + 26.67

    But that doesn't account for the different weight distribution F vs R.

    And It suggests 90 psi for my 25mm tryes and 10.5 stone weight, whereas I run 80 rear and 65 front
  • ai_1
    ai_1 Posts: 3,060
    I'm about 88kg on Fulcrum Racing 7 rims and Conti 4 seasons 25mm tyres.
    Contis are fairly narrow for "25s" and I use about 80-90psi front and 95-110psi rear depending on road, weather and ride type. (wet or bad road expected = lower pressure. Dry, smooth and plan to sprint or climb out of the saddle = higher pressure). I've used pressures as low as 70 or so at the front without problems except that it feels a bit mushy when out of the saddle and throwing the bike around.
  • cycleclinic
    cycleclinic Posts: 6,865
    100psi is normal. 90 works too if you are light. Ulteatley there is no right and wrong. Run the pressure you are comfortable with.
    http://www.thecycleclinic.co.uk -wheel building and other stuff.
  • crankycrank
    crankycrank Posts: 1,830
    thecycleclinic wrote:
    100psi is normal. 90 works too if you are light. Ulteatley there is no right and wrong. Run the pressure you are comfortable with.
    +1. Experiment. I like a cushy feel and usually run as little pressure as possible without risking denting my rims over small potholes. It sometimes works out to be close to the same as the recommended pressures by the mfrs. but not always. Others like to have higher pressure and a firmer feel. Personal preference.

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