wider tire, lower rolling resistance? - Page 2
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  1. #26
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    Pushing limits

    Quote Originally Posted by drewmcg
    When I rode Krylions (formerly Carbons), I routinely pushed the rear tire pressure to 120lbs (even 125lbs) with no problem whatsoever, so I find Michelein's max pressure recommendations to be extremely conservative (vs. Maxxis, which is perhaps too generous).
    You make it sound like being able to run at 125 psi is a good thing. In practice, pressures that high mean rapid tire wear, poor traction, discomfort, and no increase in speed because the tire is unable to conform to road surface irregularities. People think that high pressures are faster because the tires "feel faster" but real road measurements don't support the "feelings."

  2. #27
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    Quote Originally Posted by Kerry Irons
    You make it sound like being able to run at 125 psi is a good thing. In practice, pressures that high mean rapid tire wear, poor traction, discomfort, and no increase in speed because the tire is unable to conform to road surface irregularities. People think that high pressures are faster because the tires "feel faster" but real road measurements don't support the "feelings."
    Well, per Michelin's chart, they show a straight line increase in recommended pressure with increase in rider weight. For their 23c, they recommend max of 116 psi @ rider weight of 175 lbs. At the time (I didn't really know better) I was 40-50 lbs over that weight on a 23c.

    Since then I've wised up and now use 25c tires. I'm still experimenting with pressures, but generally run 100-110 front and 115-120 rear. The Vredestein Fortezza Tricomp's I'm training with now are rated to 145psi (I've seen some tires rated 165). I've also heard that some tires have a construction that favors higher psi because the higher threadcount makes them more supple (conforming to road irregularities) even at higher pressure. I do strive for lower pressure without loss of handling or pinch flats, however, to maximize comfort over the long haul . . . .

  3. #28
    Albert Owen
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    Yesterday - downhill -
    Bike 1 - 23cs @ 120psi - top speed = 45.4mph
    Bike 2 - 25cs @ 100psi - top speed = 44.2mph

    Measured using Garmin 705. Bike 2 is heavier than Bike 1, because Bike 1 has wheels which are 400grams lighter.

    My conclusion is that the effect of tyre difference is insignificant.

  4. #29
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    Does installing a tire liner (like Mr. Tuffy) alter a tire's rolling resistance?

    Does a 25 tire have better dampening characteristics than a 23?

    I'm a chubby dude, about 210 lbs. I have one bike with 23s and another with 25. Both have identical components. For both bikes, I inflate the tires to about 115psi. There's no thought process when I pump it to 115 psi. The tire says 115 psi, so I pump it to 115 psi. Reading your posts makes me realize that I may want to pay attention when I pump. Good information.

    I ride both bikes often (commuting and long weekend rides), but I find that I don't need to put a lot of effort to maintain speed or cadence on the bike with 25s. It just keeps rolling, even when I have a head wind. It also feels a lot smoother. The bike with 23s is a different story. I need to constantly work to keep it rolling, maintaining speed and cadence. The ride is definitly not as smooth as the 25.

    Is 25 tire a better choice for me?

    Your feedback would be very much appreciated.
    Thanks for all the great information.
    Kind Regards,
    bubbha70
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    Aloha from NorCal!

  5. #30
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    Quote Originally Posted by bubbha70
    Does installing a tire liner (like Mr. Tuffy) alter a tire's rolling resistance?

    Does a 25 tire have better dampening characteristics than a 23?

    I'm a chubby dude, about 210 lbs. I have one bike with 23s and another with 25. Both have identical components. For both bikes, I inflate the tires to about 115psi. There's no thought process when I pump it to 115 psi. The tire says 115 psi, so I pump it to 115 psi. Reading your posts makes me realize that I may want to pay attention when I pump. Good information.

    I ride both bikes often (commuting and long weekend rides), but I find that I don't need to put a lot of effort to maintain speed or cadence on the bike with 25s. It just keeps rolling, even when I have a head wind. It also feels a lot smoother. The bike with 23s is a different story. I need to constantly work to keep it rolling, maintaining speed and cadence. The ride is definitly not as smooth as the 25.

    Is 25 tire a better choice for me?

    Your feedback would be very much appreciated.
    Thanks for all the great information.
    25s are probably better for you because they hold roughly double the volume of air that a 23 has and give you better cushioning, as you've already noticed. I'm roughly the same weight and I switched to 25s a couple of years ago and never looked back.
    To the troll mobile, away...

  6. #31
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    Quote Originally Posted by bubbha70
    Does installing a tire liner (like Mr. Tuffy) alter a tire's rolling resistance?

    Does a 25 tire have better dampening characteristics than a 23?

    I'm a chubby dude, about 210 lbs. I have one bike with 23s and another with 25. Both have identical components. For both bikes, I inflate the tires to about 115psi. There's no thought process when I pump it to 115 psi. The tire says 115 psi, so I pump it to 115 psi. Reading your posts makes me realize that I may want to pay attention when I pump. Good information.

    I ride both bikes often (commuting and long weekend rides), but I find that I don't need to put a lot of effort to maintain speed or cadence on the bike with 25s. It just keeps rolling, even when I have a head wind. It also feels a lot smoother. The bike with 23s is a different story. I need to constantly work to keep it rolling, maintaining speed and cadence. The ride is definitly not as smooth as the 25.

    Is 25 tire a better choice for me?

    Your feedback would be very much appreciated.
    Thanks for all the great information.
    Yes. Read your post--you've answered your own question . . .

  7. #32
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    Quote Originally Posted by albert owen
    Yesterday - downhill -
    Bike 1 - 23cs @ 120psi - top speed = 45.4mph
    Bike 2 - 25cs @ 100psi - top speed = 44.2mph

    Measured using Garmin 705. Bike 2 is heavier than Bike 1, because Bike 1 has wheels which are 400grams lighter.

    My conclusion is that the effect of tyre difference is insignificant.
    Your n=1 experiment actually implies that there is a significant difference (>2.6%) between the two sets of tires. Bike 2 should theoretically roll much faster (heavier wheels, heavier bike).

    However, your lack of controlling variables makes the experiment insignificant. Big difference.

  8. #33
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    [QUOTE=iliveonnitro] Bike 2 should theoretically roll much faster (heavier wheels, heavier bike).QUOTE]

    This assumes that the heavier weight of the 25c's rolling downlhill more than compensate for their greater rolling resistance and diminished aerodynamics over the 23c's . . . .

  9. #34
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    Quote Originally Posted by California L33
    25s are probably better for you because they hold roughly double the volume of air that a 23 has and give you better cushioning...
    Well, 25s hold more air, but not double.

    Assuming the same tire pressure, a 25 would hold around 20% more air than a 23.

    This also assumes the given tire sizes are accurate. Sometimes a '25' is not a 25, it measures larger or smaller than 25mm. Ditto 23s to some extent.
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  10. #35
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    Just got me a set of Specialized Roubaix Armadillo Elite tires, 700 x 23/25.
    From what I understand the casing is 25 and the tread is 23.
    Theoretically you get the comfort of a 25 with the performance of a 23.
    Plus, you get the puncture resistance of an Armadillo.

    I did a 60 mile ride with them yesterday. They feel good.

    $60 per tire.
    Kind Regards,
    bubbha70
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    Aloha from NorCal!

  11. #36
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    Quote Originally Posted by SystemShock
    http://www.vintagebicyclepress.com/images/TireDrop.pdf

    Read carefully, and remember, the chart is per wheel, your bike and equipment weigh something too, and the back wheel takes on more than 50% of the weight.
    .

    This system makes no sense to me. Tell me if I'm reading it wrong. According to this article, on a race bike the rear tire should have 50% more pressure than the front (40/60% weight distribution). I have never heard of anyone running anything like 80psi/120psi (Front/Rear) or 90/135. For me, 140 lbs body weight plus ca. 20 lbs bike and gear times .4 is 64 lbs on the front tire, and so the recomended pressure for 23 mm tires is about 65psi. That seems absurdly low to me. I run about 95/100. It's based on trial and error and comparing myself to other riders, not on anything objective or scientific, but stil...

  12. #37
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    Quote Originally Posted by mendo
    This system makes no sense to me. Tell me if I'm reading it wrong. According to this article, on a race bike the rear tire should have 50% more pressure than the front (40/60% weight distribution). I have never heard of anyone running anything like 80psi/120psi (Front/Rear) or 90/135. For me, 140 lbs body weight plus ca. 20 lbs bike and gear times .4 is 64 lbs on the front tire, and so the recomended pressure for 23 mm tires is about 65psi. That seems absurdly low to me. I run about 95/100. It's based on trial and error and comparing myself to other riders, not on anything objective or scientific, but stil...
    Well, when I use that chart, I always assume a 45%/55% front-rear weight split. I'm not quite sure where Heine got 40/60 from for racing bikes (though he does use 45/55 for touring bikes)... I've heard the 45/55 figure for racing bikes a lot more frequently, I think it was even in LeMond's book, for example.

    But yeah, even then you're going to see a rec of something like 70-75psi front and 90 psi rear for 23mm tires. That isn't that crazy... you're a very light rider. You also don't have to run the same size tire front and rear. I think what the chart's telling you is that you're light enough to run a 20mm up front (@ about 85-90 psi) if you want, to save a little weight, and be a little more aero (though I myself am not a narrow tire fan).

    But y'know, charts, even the best ones, are just guidelines. You shouldn't feel like you're riding 'wrong' just because you ride with a tire drop that isn't precisely 15%. Personal preferences will always play a role.
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  13. #38
    pgk
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    I have and still use Pro Race 3's 23mm, but a couple of months ago tried a pair of Vittoria Open Corsa II's 25mm and was pleasantly suprised as to how much better they ride. Been playing around with varying the tire pressure mostly lower than what I used in the past and so far it's been all good. I can't really tell if there is more rolling resistance from using lower tire pressure but the ride sure improved.

  14. #39

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    Does anyone here really believe that all this theoretical stuff is going to be meaningful when talking about a 25 mm vs a 23 mm tire of the same make and model?

    Just try it for yourselves. Basically, the 25 will absorb a little more road shock over cracks in the pavement sort of thing, but only if it's inflated less than your 23 mm tire would have been. You might feel a tiny bit more rolling resistance too, but again, only if the 25's inflation is less than the 23's.

    There is probably going to be a more significant difference in protection of the rim, just because the larger tire overlaps the rim more, and you might find that your bike handles a touch slower or more squishy with the larger tire (especially on the front).

    But if you're looking for performance improvement in terms of average speed on a long ride, you should probably look elsewhere. Again, this all assumes comparing apples with apples, ie. a 23 and a 25 both of the same make and model.

  15. #40
    pgk
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    I have tried it, and the 25 offers a smoother ride period. I don't race I just ride for fun, so if the smoother ride comes at the expense of ever so slightly more rolling resistance so be it. I think I'm going to try out a 23 in front and 25 in back.. What do ya think??

  16. #41

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    Like I said, all the theoretical stuff implies same inflation pressure. I personally prefer 25 mm tires, because I don't pump them up as much and I enjoy the little bit smoother ride it gives me over the average paved road. I wouldn't care even if it does impact performance, because I'm not looking for that. I just want to ride my road bike at whatever pace feels good for the distances I'm covering, and I really don't care about who passes me, or what my average speed is. After decades of riding, I'm not the type that reads magazine articles about more power or more speed. Heck, I wasn't one of those even in my younger days.

    Also, I didn't mention this in my previous post, but I do find that 25's let me ride on gravel or off-pavement more easily whenever I feel the need to do so. This is where rim protection comes in handy. I would even use 28 mm tires if I had to, but I'm pretty light, so 25 is just about right.

  17. #42

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    Quote Originally Posted by justriding
    Like I said, all the theoretical stuff implies same inflation pressure. I personally prefer 25 mm tires, because I don't pump them up as much and I enjoy the little bit smoother ride it gives me over the average paved road. I wouldn't care even if it does impact performance, because I'm not looking for that. I just want to ride my road bike at whatever pace feels good for the distances I'm covering, and I really don't care about who passes me, or what my average speed is. After decades of riding, I'm not the type that reads magazine articles about more power or more speed. Heck, I wasn't one of those even in my younger days.

    Also, I didn't mention this in my previous post, but I do find that 25's let me ride on gravel or off-pavement more easily whenever I feel the need to do so. This is where rim protection comes in handy. I would even use 28 mm tires if I had to, but I'm pretty light, so 25 is just about right.
    Great post. I just put a 28 rear on one of my bikes and will never go below 25 again. I have some 23's I have to use up though..

  18. #43
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    I've been wanting to try 25's for awhile and just found some Pro2 Race 25's on eBay.

    I got a pair and there should be 7 pair remaining if anyone is interested.

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