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    Senior Member Jarrett2's Avatar
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    What's the correct tire pressure for a Clyde on a 700x25 road tire?

    I'm at 260 and ride a Roubaix with 700x25 tires. One one wheelset I have Specialized Espoir tires, on my other wheelset I have Ultra Gatorskins. I think both tires read 130 max on the side. What would be the optimal tire pressure for these? Thanks.

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    Travelling hopefully chasm54's Avatar
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    Quote Originally Posted by Jarrett2 View Post
    I'm at 260 and ride a Roubaix with 700x25 tires. One one wheelset I have Specialized Espoir tires, on my other wheelset I have Ultra Gatorskins. I think both tires read 130 max on the side. What would be the optimal tire pressure for these? Thanks.
    Read this. At your weight, you're going to need the maximum pressure at the rear. The chart's pretty easy to interpret.
    There have been many days when I haven't felt like riding, but there has never been a day when I was sorry I rode.

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    Senior Member Black wallnut's Avatar
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    Likely somewhere between 110 and 130 psi as long as you do not pinch flat.


    Mark

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    There is also a max. pressure on your rims. You should also check to see what your rims are rated for PSI for 25mm width. I choose to inflate mine to max. recommended pressure on the back and about 8-10% less PSI in the front tire.

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    Senior Member adrien's Avatar
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    How wide are your rims? A wider rim can handle lower pressure without pinch-flatting.

    I'm 210ish. I ride:
    - on Ambrosio rims (20 mm wide) with 25s: 110 rear and 95 front. 1 pinch flat in 10,000 miles (big hole)
    - on Archetypes (23 mm wide) with 25s: 100 rear and 90 front

    Lower int he front will give you a more balanced, supple ride.
    "how do you know you can't swim until you have drowned?"

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    Senior Member Jarrett2's Avatar
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    Weight : 490 grams (700C)
    FEATURES

    6106 aluminum alloy
    Pinned
    Traditional drilling
    UB Control
    Single eyelet
    Low profile
    Clincher
    External wear indicator


    DIMENSIONS

    ETRTO compatible size: 622 x 15
    Recommended tyre widths: 19 to 32 mm
    Valve hole diameter: 6.5 mm
    Recommended nipple length: 12 mm
    Recommended rim tape: 622 x 18 x 0.6

    Any pertinent info there?

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    Travelling hopefully chasm54's Avatar
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    Quote Originally Posted by Jarrett2 View Post

    Any pertinent info there?
    None whatever. No 622 x 15 rim is going to have any problem with a 25mm, 130 psi tyre. Read the chart and inflate accordingly.
    There have been many days when I haven't felt like riding, but there has never been a day when I was sorry I rode.

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    Ex-Post-RBR Marcus_Ti's Avatar
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    Quote Originally Posted by chasm54 View Post
    None whatever. No 622 x 15 rim is going to have any problem with a 25mm, 130 psi tyre. Read the chart and inflate accordingly.
    Depends on how well the wheel is built. Any tubed or tubeless tire will measurably reduce the spoke tension in a wheel, tubeless more than tubed. And the higher that pressure the greater that effect.

    If I were 115+kg, I'd go to a larger tire size if at all possible given the frameset combo.

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    Travelling hopefully chasm54's Avatar
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    Quote Originally Posted by Marcus_Ti View Post
    Depends on how well the wheel is built. Any tubed or tubeless tire will measurably reduce the spoke tension in a wheel, tubeless more than tubed. And the higher that pressure the greater that effect.

    If I were 115+kg, I'd go to a larger tire size if at all possible given the frameset combo.
    I'd go to a larger tyre too, but for reasons of comfort, not wheel failure. And lets not forget that the bigger the tyre, the greater the stress on the rim. It's a function of pressure and volume, not just pressure.
    There have been many days when I haven't felt like riding, but there has never been a day when I was sorry I rode.

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    Senior Member adrien's Avatar
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    Quote Originally Posted by chasm54 View Post
    None whatever. No 622 x 15 rim is going to have any problem with a 25mm, 130 psi tyre. Read the chart and inflate accordingly.
    Disagree. The recommended tape width of 18mm suggests to me this is a standard-width road rim, likely 19mm. So if we assume that, then the sweet spot with 25s for this size ride I would say is likely about 115 rear and a little less (105-110) up front.
    "how do you know you can't swim until you have drowned?"

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    staring at the mountains superdex's Avatar
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    Be careful reading that chart. Its own caption reads, "The loads are for each wehel[sic] not the entire bike"

    You'll have to play around with the relative pressures front/rear -- I regularly square off tires when I use the pressures in that chart. (squared tire==overinflation)

    for anecdotal reference, I'm right around 200lbs, and ride 100psi on 25mm tires (front and rear). When I ride on 23s, I ride at like 105psi.

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    Just Plain Slow PhotoJoe's Avatar
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    I have no idea what YOU should do. I'm 240 and inflate to 105 f and 110 rear. Never had a problem.
    If at first you don't succeed, Skydiving is not the sport for you!

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    Senior Member john4789's Avatar
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    I weigh 240lbs. I usually ride max rated in the front and around 110% max in the rear at the start of the week. I do that so I end up at the max ratings at the end of the week w/o topping off - cause I'm lazy.

    I run my 'road' bike with 700x32s at 100psi front and 110psi rear. My mountain bike with 26x1.9s run at 65psi front and 75psi rear.

    At 260 you should be riding the max rated for the 700x25 tire w/o question.

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    I am between 373 and 384 pounds depending on time of day, what I am wearing, what I have eaten, etc... I inflate my Vitora tires (700 x 25mm slicks) to the max listed on the tire which is 130.

    I usually inflate to about 135 and remove the tire pump which has me bleeding off five to 10 pounds in the process. as the air hose takes a bit of work to get off of the tire.

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    Senior Member Jarrett2's Avatar
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    Thanks for all of the input so far.

    Sounds like max on the back, any reason to go max on the front as well? Or knock it down a few lbs?

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    Guys for reference Jarrett2 is speaking about Mavic Open Sport rims. Given his lower spoke count wheels came with the Roubaix, I'm going to assume that those are what the Espoirs are mounted on. And, that the Open Sports have the Ultra Gatorskins.

    Personally, I'm riding a 25/28mm combo, at the same weight as you. If I were running a 25mm rear I would be inflating it to at least 120+psi. Probably closer to 130psi. I do inflate the 28s I'm on to 116psi/8bar. Keep in mind that indicated maximum pressures on tires are a bit of an ad hoc afair. It's not as though they represent a crisp clear black line, below which everything is oakey dokey and above which bad things are likely to happen. The are a "Recommended" maximum value.

    If you ever feel yourself bottom your tire out against the rim or suffer a pinch flat, you're running too little pressure and should increase it.
    Birth Certificate, Passport, Marriage License Driver's License and Residency Permit all say I'm a Fred. I guess there's no denying it.

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    Senior Member Jarrett2's Avatar
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    Yep, in this case I'm talking about two diff wheelsets:

    Fulcrum S5 wheel 18/24h with Specialized Espoir 25c tires
    Mavic Open Sport 32/32h with Ultra Gatorskins 25c tires

    If I'm not imagining it, the front Mavic 32h wheel felt more bouncy at the same 110+ psi I was running the Fulcrum S5 16h wheel at.

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    Senior Member bmthom.gis's Avatar
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    Hmm, I hover around 205...I never inflate to more than 100 PSI on my road bike (25 mm wide)....my wheels have a low spoke count and I haven't had a problem yet. I never inflated more then 100 when I had 23s either. That's just me, though
    "All of the true things that I am about to tell you are shameless lies."

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    Quote Originally Posted by Jarrett2 View Post
    Thanks for all of the input so far.

    Sounds like max on the back, any reason to go max on the front as well? Or knock it down a few lbs?
    Yes, you could run front a little lower, maybe 120.

    Keep in mind in all of this that nothing terrible happens just because you vary tire pressure a bit. It's not science, and experimenting is par for the course. You certainly don't want to head out way under pressure and damage a tire/tube/rim. You're definitely going to be on the high side of the range (i.e. 110+), so start at max and adjust down to see how it impacts ride quality (provided you are somewhat careful and do not to slam through rough stuff, you can ride lower psi; if you're roads are in good repair and smooth, you can run lower psi).

    For the record, I'm 215-220lbs and run 23s 110F/115-120R off a 40/60 weight bias. I could definitely go lower psi up front, but run a lot of bar drop and sprint hard out of the saddle on a bike with steep angles, so I need my front tire to be firm and responsive.

    That's a traditional width rim, tubed. On my tubeless wide rims, also 23s, I run 95-100F/105R.
    Last edited by chaadster; 10-09-14 at 07:16 AM.
    Chaad--'95 DeKerf Team SL, '02 Lemond Buenos Aires, '05 Novara Buzz, '73 Schwinn Collegiate, '06 Mountain Cycle Rumble, '09 Dahon Mariner D7, '12 Mercier Nano, '12 Breezer Venturi

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    Hrm, I'm reading the post and I think I may be doing it wrong. I have a set of Fulcrum Racing 7's with 700x25 tires and just put 120 psi on both tires per the bike shop. I'm 5'9 and 220. Not sure how wide the wheel is, but the chart below gives me just over 115. Do I put this amount in both tires or a little less in the front and a little more in the back?

    Calculate Rear tire pressure:
    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

    Front Pressure = .9*Rear Pressure

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    Travelling hopefully chasm54's Avatar
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    Quote Originally Posted by LGHT View Post
    Hrm, I'm reading the post and I think I may be doing it wrong. I have a set of Fulcrum Racing 7's with 700x25 tires and just put 120 psi on both tires per the bike shop. I'm 5'9 and 220. Not sure how wide the wheel is, but the chart below gives me just over 115. Do I put this amount in both tires or a little less in the front and a little more in the back?

    Calculate Rear tire pressure:
    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

    Front Pressure = .9*Rear Pressure
    Read the article linked in post#2. As ypu'll see, the weights are per wheel, rather than for the bike as a whole, and you can assume that your weight is distributed roughly 60/40 back/front.
    There have been many days when I haven't felt like riding, but there has never been a day when I was sorry I rode.

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    Quote Originally Posted by chasm54 View Post
    Read the article linked in post#2. As ypu'll see, the weights are per wheel, rather than for the bike as a whole, and you can assume that your weight is distributed roughly 60/40 back/front.
    That doesn't make sense though. Based on the chart I would put 90psi in the front and 110psi in the back? Seems like it's all opinion based and the number from chart to chart vary significantly.

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    Quote Originally Posted by LGHT View Post
    Hrm, I'm reading the post and I think I may be doing it wrong. I have a set of Fulcrum Racing 7's with 700x25 tires and just put 120 psi on both tires per the bike shop. I'm 5'9 and 220. Not sure how wide the wheel is, but the chart below gives me just over 115. Do I put this amount in both tires or a little less in the front and a little more in the back?

    Calculate Rear tire pressure:
    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

    Front Pressure = .9*Rear Pressure
    Quote Originally Posted by chasm54 View Post
    Read the article linked in post#2. As ypu'll see, the weights are per wheel, rather than for the bike as a whole, and you can assume that your weight is distributed roughly 60/40 back/front.
    Quote Originally Posted by LGHT View Post
    That doesn't make sense though. Based on the chart I would put 90psi in the front and 110psi in the back? Seems like it's all opinion based and the number from chart to chart vary significantly.
    It's not so much that the formulas and their associated charts are opinion based as much as they're simply a recommended starting point for what is ultimately a solution determined by circumstances.
    Those riding on smooth asphalt devoid of pot holes may find that reduced pressure is required for traction reasons and that in the absence of broken pavement they do not need to concern themselves with pinch flats.
    Two riders on an identical bike may adopt extremely different positions resulting in different weight distribution between the front and rear wheels.
    Riders on particularly coarse chip seal may reduce their pressure for comfort reasons.
    Those seeking the lowest possible rolling resistance on smooth pavement may increase theirs'.
    Some may run the same size front and rear. Others may run a wider rear, narrower front combo for any one of a number of reasons.
    The width of the rim will effect the profile of a tire and could result in more or less pressure being required to achieve the desired ride quality.

    The charts and formulas are just a suggested starting point based on any one of several criteria, tire drop probably being the most common. But, they are not gospel.

    They are a good point to start if one is inexperienced enough with their tires to ask, "what pressure should I be running?"

    Then adjust to suit your particular circumstances.
    Birth Certificate, Passport, Marriage License Driver's License and Residency Permit all say I'm a Fred. I guess there's no denying it.

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    Quote Originally Posted by bigfred View Post
    It's not so much that the formulas and their associated charts are opinion based as much as they're simply a recommended starting point for what is ultimately a solution determined by circumstances.
    Those riding on smooth asphalt devoid of pot holes may find that reduced pressure is required for traction reasons and that in the absence of broken pavement they do not need to concern themselves with pinch flats.
    Two riders on an identical bike may adopt extremely different positions resulting in different weight distribution between the front and rear wheels.
    Riders on particularly coarse chip seal may reduce their pressure for comfort reasons.
    Those seeking the lowest possible rolling resistance on smooth pavement may increase theirs'.
    Some may run the same size front and rear. Others may run a wider rear, narrower front combo for any one of a number of reasons.
    The width of the rim will effect the profile of a tire and could result in more or less pressure being required to achieve the desired ride quality.

    The charts and formulas are just a suggested starting point based on any one of several criteria, tire drop probably being the most common. But, they are not gospel.

    They are a good point to start if one is inexperienced enough with their tires to ask, "what pressure should I be running?"

    Then adjust to suit your particular circumstances.
    Wow now I have to adjust based on the road I'm ridding... Now I know why the LBS just told me to put 120 lol and didn't bother explaining as to why.

    I do notice a lot of "vibration" on certain rides at 120 so I'm going to back the front down to 105 and the bike to 110 and ride and re-adjust accordingly.

    Thanks for the explanation.

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    Travelling hopefully chasm54's Avatar
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    Quote Originally Posted by LGHT View Post
    That doesn't make sense though. Based on the chart I would put 90psi in the front and 110psi in the back? Seems like it's all opinion based and the number from chart to chart vary significantly.
    It isn't just "opinion". It's clear from the tests that roughly 15% deflection in the shape of the tyre offers the least rolling resistance. From there it's a relatively simple matter to calculate the pressures appropriate to the load. As Fred says, that may vary somewhat according to circumstances, but it isn't just "opinion".

    It makes perfect sense, anyway. If there is more weight on the rear wheel, why wouldn'r it be sensible to inflate that to a greater pressure than the front? Especially since the front is where you want most traction.
    There have been many days when I haven't felt like riding, but there has never been a day when I was sorry I rode.

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