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Recommended Tyre Pressure

n733lkn733lk Posts: 44
edited February 2017 in Road general
I've just put 28mm types on my road bike. (Yay!). There is a pressure range on the sidewalls (Max of 95lbs).

I ride on primarily well paved roads in Texas and weigh approximately 210 lbs (95kg).

What would be a good pressure to start with?

Thanks!!

Posts

  • cyclecliniccycleclinic Posts: 6,863
    whatever you feel comfortable with but above 100psi is probably silly. you might like pressures as low as 60 psi. it really depends on you, the tyre and the roads.
    http://www.thecycleclinic.co.uk -wheel building and other stuff.
  • keef66keef66 Posts: 13,286
    Not so low that you're getting pinch flats and you can feel the tyre squirming when you change direction, and not so high you shake your fillings out on anything other than smooth tarmac.

    I'd start at 85 rear, 70 front and see what happens, but only you can tell really
  • bigmatbigmat Posts: 5,108
    I had to pump up my 28s last night after a rear flat. Put 85 in front and rear, which is fine on normal roads. FWIW tyre pressure on the front wheel before I pumped it up was 60PSI and that felt fine. Have run significantly lower over the cobbles (maybe 40?) although go too low and you run the risk of pinch flats, rim dings etc. I'm 85kg for reference.
  • try this video and download https://www.youtube.com/watch?v=Clk_LLBYFzA
  • I've been experimenting with ~55/61PSI on 38c tyres the last few days, on my ~12Kg bike and me being ~82Kg all kitted out. Not sure if it was the wind and/or my legs being a bit tired after work, but they felt a bit draggy on the way home today, so I've boosted the pressures to ~63/71PSI.

    Typically I've been running ~70/77PSI, but around 11th Feb, I randomly increased them to ~77/83PSI... I then had the front tyre go from under me on Valentine's afternoon, while trying to turn right at a mini roundabout at roughly my usual speed!

    Consequently, pressures got reduced back to normal and considering how sore I was that first night, I was amazed to feel up to riding again the next day... While taking 90 degree bends far more cautiously than I was!
    ================
    2017 Cube Attain GTC Pro Disc 2016
    2016 Voodoo Wazoo
  • hambinihambini Posts: 113
    Me being the engineering purest, pumps up to the sidewall max. Any lower than that and you are increasing rolling resistance. However that needs to be offset by whether you can handle the slightly less than smooth ride.
  • I often go between 80 and 90psi on my 28s. I'm 75kg.
  • shortfallshortfall Posts: 2,091
    hambini wrote:
    Me being the engineering purest, pumps up to the sidewall max. Any lower than that and you are increasing rolling resistance. However that needs to be offset by whether you can handle the slightly less than smooth ride.

    Im not an expert on this by any stretch, but doesn't recent research indicate that pumping tyres rock hard causes bouncing on imperfect road surfaces which actually increases rolling resistance?
  • drwaedrwae Posts: 308
    hambini wrote:
    Me being the engineering purest, pumps up to the sidewall max. Any lower than that and you are increasing rolling resistance. However that needs to be offset by whether you can handle the slightly less than smooth ride.

    I was always a big fan of inflating to max 120psi and I never knew any different but I started trying 75 front 85 rear and the terrible Scottish roads suddenly became a LOT more comfortable . I use 25mm tyres. It didn't affect my speed according to strava/garmin
  • bungle73bungle73 Posts: 735
    shortfall wrote:
    hambini wrote:
    Me being the engineering purest, pumps up to the sidewall max. Any lower than that and you are increasing rolling resistance. However that needs to be offset by whether you can handle the slightly less than smooth ride.

    Im not an expert on this by any stretch, but doesn't recent research indicate that pumping tyres rock hard causes bouncing on imperfect road surfaces which actually increases rolling resistance?

    This^
  • bungle73bungle73 Posts: 735
    During my research on this I found this set of formulae for working out the correct road bike tyre pressure. I found it gives a slightly different result from the one given by the YT video, but I'm not sure which is the better system.

    Tyre Width=20: = (0.33 * Rider Weight in lbs) + 63.33
    Tyre Width=23: = (0.33 * Rider Weight in lbs) + 53.33
    Tyre Width=25: = (0.33 * Rider Weight in lbs) + 43.33
    Tyre Width=28: = (0.33 * Rider Weight in lbs) + 33.33
    Tyre Width=32: = (0.17 * Rider Weight in lbs) + 41.67

    Front pressure 0.9 x rear pressure.
  • I don't like the ambiguity in these formulas, where they state "rider weight."

    I'd much rather they stated "fully kitted out rider weight," which could easily be a few kilos more. And don't forget to include your water bottle, if applicable.;)
    ================
    2017 Cube Attain GTC Pro Disc 2016
    2016 Voodoo Wazoo
  • n733lkn733lk Posts: 44
    bungle73 wrote:
    During my research on this I found this set of formulae for working out the correct road bike tyre pressure. I found it gives a slightly different result from the one given by the YT video, but I'm not sure which is the better system.

    Tyre Width=20: = (0.33 * Rider Weight in lbs) + 63.33
    Tyre Width=23: = (0.33 * Rider Weight in lbs) + 53.33
    Tyre Width=25: = (0.33 * Rider Weight in lbs) + 43.33
    Tyre Width=28: = (0.33 * Rider Weight in lbs) + 33.33
    Tyre Width=32: = (0.17 * Rider Weight in lbs) + 41.67

    Front pressure 0.9 x rear pressure.

    This definitely does not work for me! I'd be riding my 28s @ 103 and 92. Youser!!!!
  • drwaedrwae Posts: 308
    n733lk wrote:
    bungle73 wrote:
    During my research on this I found this set of formulae for working out the correct road bike tyre pressure. I found it gives a slightly different result from the one given by the YT video, but I'm not sure which is the better system.

    Tyre Width=20: = (0.33 * Rider Weight in lbs) + 63.33
    Tyre Width=23: = (0.33 * Rider Weight in lbs) + 53.33
    Tyre Width=25: = (0.33 * Rider Weight in lbs) + 43.33
    Tyre Width=28: = (0.33 * Rider Weight in lbs) + 33.33
    Tyre Width=32: = (0.17 * Rider Weight in lbs) + 41.67

    Front pressure 0.9 x rear pressure.

    This definitely does not work for me! I'd be riding my 28s @ 103 and 92. Youser!!!!

    Using that I should be running my 25s at 90psi rear and 81psi front which isn't far off what I actually use, I guess it works well up to a point
  • hambinihambini Posts: 113
    shortfall wrote:
    hambini wrote:
    Me being the engineering purest, pumps up to the sidewall max. Any lower than that and you are increasing rolling resistance. However that needs to be offset by whether you can handle the slightly less than smooth ride.

    Im not an expert on this by any stretch, but doesn't recent research indicate that pumping tyres rock hard causes bouncing on imperfect road surfaces which actually increases rolling resistance?

    I have also heard this but I can't say I've ever experienced it. When I let my tyres down to a lower pressure I can feel the increased drag but I don't think the level of cushioning offsets the increased contact patch.

    My theory is the tyre acts like a spring damper combination. If you change the tyre pressure you change the natural frequency of it. If you are unfortunate to have a combined mass of rider and bike that sits you in the natural frequency of the road imperfections, the bike will vibrate. My combined bike+me is ~80kg and I don't think it seems to affect me as much.

    Again, this is just me from experience, I have no valid data to back any of this up.
  • bungle73bungle73 Posts: 735
    hambini wrote:
    shortfall wrote:
    hambini wrote:
    Me being the engineering purest, pumps up to the sidewall max. Any lower than that and you are increasing rolling resistance. However that needs to be offset by whether you can handle the slightly less than smooth ride.

    Im not an expert on this by any stretch, but doesn't recent research indicate that pumping tyres rock hard causes bouncing on imperfect road surfaces which actually increases rolling resistance?

    I have also heard this but I can't say I've ever experienced it. When I let my tyres down to a lower pressure I can feel the increased drag but I don't think the level of cushioning offsets the increased contact patch.

    My theory is the tyre acts like a spring damper combination. If you change the tyre pressure you change the natural frequency of it. If you are unfortunate to have a combined mass of rider and bike that sits you in the natural frequency of the road imperfections, the bike will vibrate. My combined bike+me is ~80kg and I don't think it seems to affect me as much.

    Again, this is just me from experience, I have no valid data to back any of this up.

    You're over thinking this. If you run a solid wheel (which is basically what you have with a tyre pumped up to max) over a rough surface, such as a road, it will have to ride up and down every imperfection, which a) will naturally slow it down, and b) create a harsh ride for the vehicle that it is attached to. The whole point of using a pneumatic tyre is to smooth out the imperfections found on the usual road surface. The only place where where a rock hard wheel is faster is on the smooth wooden floor of a velodrome, and no road is like that.

    You might think that a hard tyre is "faster" due to all the vibration that you feel, but it really isn't. That vibration is slowing you down.
  • Harry182Harry182 Posts: 739
    ajmitchell wrote:

    Just watched the above -- Good link.

    He also provides a link to an spreadsheet tire pressure calculator that handles variables including rider/bike weight, tire width and road surface. Seems like a better place to start.
  • n733lkn733lk Posts: 44
    Saw this. He's got some good stuff.
  • imposter2.0imposter2.0 Posts: 10,819
    hambini wrote:
    Me being the engineering purest, pumps up to the sidewall max. Any lower than that and you are increasing rolling resistance.
    Wrong. A tyre will roll better at optimum pressure, not max pressure - the two are not the same.
  • n733lk wrote:
    I've just put 28mm types on my road bike. (Yay!). There is a pressure range on the sidewalls (Max of 95lbs).

    I ride on primarily well paved roads in Texas and weigh approximately 210 lbs (95kg).

    What would be a good pressure to start with?

    Thanks!!

    I'm around that sort of weight, I have 33mm tyres which I run around the 60psi mark.

    bare in mind most pumps are not that accurate.

    But a lot will depend on you, some folks like the zing of higher pressures and other don't mind the vagueness of much lower it really is try and see.
  • bungle73bungle73 Posts: 735
    GCN's latest video is on tyre pressure: https://www.youtube.com/watch?v=4sDX54zNmxY

    According to their system I should put 58 psi in the front and 63 in the rear on my 28s, which seems a bit low, and is quite a bit lower than what I'm running them at atm. Si runs his about there, and he is only 2 kg heavier than me, so I guess it must be ok?
  • 82r 77f psi @ 75kg rider weight ;)
    2016 Giant Defy Advanced Pro 0
    2012 Scott Foil 40
    2009 Spesh Allez Elite
    2005 Rocky Mountain Element 70
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