Why not 28mm tires? - Page 3
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  1. #51
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    Quote Originally Posted by Argentius View Post
    Why does everyone equate squishiness to a "better" ride?

    Touring bikes should be plush.

    I do not think racing bikes should be.

    Note that pro racers have the options they use on Roubaix -- wider rims, 25mm tires -- available to them every day, and, bike manufacturers would be happy to give them a little more clearance if that would help.

    I notice they do not make this choice. Granted, some pro racers also take the middle out of their bread and refuse to use the air conditioner.
    I could also ask, why does everyone equate stiffness with better performance?

    Motorcycle manufacturers made their alloy frames less stiff for better performance.

    It is well known in the transportation industry that vibrations cause fatigue.

    Tires more than any other component on a bicycle can damp vibrations.

    As you've pointed out above, the superstitions and traditions of pro's may outstrip their logical thinking on the matter.

    The OP is "why not 28mm tires?" IMHO, there are very few good reasons, "why not?"

    Two of them were given by Kerry Irons. The rest of the reasons are, not so good.

  2. #52
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    I read some folks stating their 27-28mm tyres would not clear the (open) brake pads unless mostly deflated but 25-26mm width would just make it - on 100psi - with no room to spare....

    I ride on 25mm tyres (actual width ~26-27mm in any case). My front tyre pressure is 10psi less than my rear tyre pressure. That seems to work well.

  3. #53
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    I wonder if those folks know how to operate their brake QR.
    They do anything just to win a salami in ridiculous races. I take my gear out of the car and put my bike together. Tourists and locals are watching from sidewalk cafes. Non-racers. The emptiness of those lives shocks me. It was the illest of times, it was the dopest of times. And we looked damn good. Actually the autobus broke down somewhere on the Mortirolo.

  4. #54
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    Quote Originally Posted by kbwh View Post
    I wonder if those folks know how to operate their brake QR.
    Some brakes just don't open much. Ciamillos are one of the offenders in the "don't open much" category...
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  5. #55
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    Ultegra ?

    Quote Originally Posted by kbwh View Post
    I wonder if those folks know how to operate their brake QR.
    when I open my Ultegra (2010 model) QR brakes there is not a lot of room for a fully inflated to 7 bar (~105psi) 25mm wide tyre to get through (the actual width ~26-27mm). Of course you can always deflate tyre first but it's extra pain to do so.....

  6. #56
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    Quote Originally Posted by tarwheel2 View Post
    I am no weight-weenie by any means. However, you will notice extra weight in wheels/tires much more so than the frame. If you can't tell the difference, you have either never used lighter tires or ride in an area with no hills. I had some bombproof wheels built for my commuter with 36H hubs and heavier rims than on my other bikes, but I ended up taking them off my bike because it rode so much slower. Trust me, it was the weight difference and I noticed it right away. I ride 7,000+ miles a year and notice things like this.
    I don't doubt that you're noticing increased road feel but that has nothing at all to do with how fast you're riding. I was riding Veloflex Paves and could feel a grain of sand on the road. Even though Armadillo's suck, (cornering at least) I much prefer the solid feel they provide over rough roads, than feeling every single imperfection on fairly smooth roads.

    Turn the cranks by hand with each one of the different weight tires you mount. That's the difference in the weight and force required and it's negligible. And believe me, I ride 10,000+ miles a year and know these small differences in weight affect comfort a great deal and speed, not so much if at all.

  7. #57
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    Quote Originally Posted by Rogus View Post
    I think someone else called this light bulbing.

    OK, so it's not solely because of it being a 28mm or larger tire, but becasue the tire width was too large for the rim. Makes sense. Is the opposite a problem? Where's the point where a tire is too narrow for a rim?
    Yes. If the tire is too narrow, it will have a shallower profile, meaning you have to run much higher pressure to avoid pinch flats. The tire will lose the roundness of its designed profile, flattening out. Cornering will be inconsistent.

  8. #58
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    My main wheels are 22-23mm tubulars on carbon hoops. My clinchers are 25mm Pro Race 3s on Hed C2 rims. The Pro Race tires measure just over 27mm on those hoops and fit in my Spooky Skeletor with Enve 2.0 fork (not much room for error).

    I run 95/100psi for the tubulars and 80/85psi for the clinchers.

    As far as clinchers go, they are the nicest riding wheels/tires I've used (I still prefer my tubulars). I definitely don't feel slower on them and the guys I ride with will agree when they are on my wheel. Unfortunately, this time of year is known for tearing up expensive, nice tires and I don't want to change a tubular in this cold weather. I so actually want to try next year's D2R2 ride with that setup. Should be a nice challenge.

    I definitely appreciate the fact that my bike can handle that tire size. It's nice to have options.

    Choose your tires for the road conditions you ride on. It's abundantly clear that different things work for different people.

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  9. #59
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    I'm running 25s on my road bike now. I'm a lightweight rider (125lb), riding on roads littered with bumps and potholes, and consequently prefer to run low pressures (I typically run 92 PSI rear, 85 front). These are both below the minimum recommended pressure on the 23s I was running before, but well within the nominal range on the 25s.

    On a hill in my area I actually do notice slightly slower top speeds in roll-down coast test due to the higher rolling resistance -- though I haven't done a large enough number of trials and averages to put a definite number on the % change (wind and temperature change a lot)

    However, I am finishing rides in faster overall average times than before, and ending with more relaxed arms/upper body due to the smoother ride. In my parciular case I think the 25s work better for me. Are they "faster" in the sense that they have less air drag and rolling resistance? absoltely not.

    I think this may be what the OP was saying when talking about 25s being faster. If for a paricular rider they result in a more comfortable ride, that *may* be true. In my case I doubt going to 28s or larger would be any better. I'm already able to run the pressures I want at 25s and feel no desire to drop them further. On 28s I'd be running into maximum pressure limits if I kept the tire PSI the same, and would have to run heavier rims and deal with slightly higher air drag and (possibly) higher rolling resistance (it's true rolling restiance mostly comes down to pressure).

    I am no weight-weenie by any means. However, you will notice extra weight in wheels/tires much more so than the frame. If you can't tell the difference, you have either never used lighter tires or ride in an area with no hills. I had some bombproof wheels built for my commuter with 36H hubs and heavier rims than on my other bikes, but I ended up taking them off my bike because it rode so much slower. Trust me, it was the weight difference and I noticed it right away. I ride 7,000+ miles a year and notice things like this.
    Rotational inertia only makes a difference during accelerations. Accelerating one gram of mass on the very surface of a tire is equivalent to accelerating two grams of ordinary mass on the bike-- because you're accelerating the wheel both linearly, and angularly, and the circumference of the wheel = the distance traveled on the road. The effect is less significant if the weight is closer to the axis of rotation (eg weight of the cassette). For steady-speed climbing only the actual weight matters.

    I agree moving from heavy to light wheels is noticeable -- rotating mass aside, a large percentage of the the weight on modern bikes is in the wheels -- but extra rotating mass shouldn't matter for climbing in particular.

    Admittedly there may be other effects from running heavier or different rims. The damping/shock absorbing characteristics like the resontant frequency of the tire+spoke+bike spring-mass systems, might change the "road feel" noticeably.

  10. #60
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    that is actually wrong.

    your postulate says that if you are going on steady speed uphill, theoretically there is no acceleration right ?

    no, that is wrong. There is an actual constant de-acceleration due to the gravitational force, that you have to overcome on every pedal stroke.

    if you stop pedaling you will deaccelerate until you start rolling downhill backwards... try it.

    hence the rotational mass acceleration indeed is present and permanently. basic dynamic phyiscs here.
    Quote Originally Posted by zank
    They're just bikes. Ride 'em in the rain, salt, snow and crap to fully appreciate them.
    Quote Originally Posted by Sean Kelly
    The thing about the cold is that you can never tell how cold it is from looking out a kitchen window. You have to dress up, get out training and when you come back, you then know how cold it is.

  11. #61
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    I don't buy your argument, Salsa unless the rider has a very choppy pedaling style.
    A normal smooth, graceful turn of the pedals will not produce changes in the angular velocity of the wheels. No resultant acceleration or deceleration, alas.

  12. #62
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    read again kbwh

    if you don't pedal you will deaccelerate fast and start going backwards ( well you will fall over first )

    why so ? gravitational force pushing you down and making you move backwards with increasing speed.

    how you overcome this constant deacceleration ? well by constantly accelerating on the other direction.

    First law of Newton.

    and before you counterargument. it is not the same as on flat land, there the gravitational force doesn't push you back, it pushes you down, you have to overcome the rotational inertia at the beginning and then keep pedaling to mantain the same speed overcoming friction and wind resistance...

    Although similar it is not the same thing. if you don't pedal on flat land, you will slowly deaccelerate due to friction ( true a lot slower than on the first case ) untill you simply don't move anymore. ( and fall over ) but you won't be pushed backwards.
    Last edited by Salsa_Lover; 11-01-2011 at 04:09 AM.
    Quote Originally Posted by zank
    They're just bikes. Ride 'em in the rain, salt, snow and crap to fully appreciate them.
    Quote Originally Posted by Sean Kelly
    The thing about the cold is that you can never tell how cold it is from looking out a kitchen window. You have to dress up, get out training and when you come back, you then know how cold it is.

  13. #63
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    Force is not accelleration.

  14. #64
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    no but the force is what make you accelerate.

    may the force with you be

    you know that in physics gravity g is acceleration right ?

    F = mg.
    Quote Originally Posted by zank
    They're just bikes. Ride 'em in the rain, salt, snow and crap to fully appreciate them.
    Quote Originally Posted by Sean Kelly
    The thing about the cold is that you can never tell how cold it is from looking out a kitchen window. You have to dress up, get out training and when you come back, you then know how cold it is.

  15. #65
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    It does and it is.
    Point is that you will not have resultant acceleration if the force is opposed by an equally large force.

  16. #66
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    Sure then


    the Force applied is F = m ( your weight ) . g ( gravity )

    So, to overcome this force and not move down you have to generate an equal force F = m (your weight ) . a ( your acceleration ) ( think a trackstand uphill )

    and to move upwards F = m.a1 your acceleration a1 has to be bigger than g

    it is clear now ?

    now think it again, the gravity acceleration g is constant. so how has to be yours ?
    Quote Originally Posted by zank
    They're just bikes. Ride 'em in the rain, salt, snow and crap to fully appreciate them.
    Quote Originally Posted by Sean Kelly
    The thing about the cold is that you can never tell how cold it is from looking out a kitchen window. You have to dress up, get out training and when you come back, you then know how cold it is.

  17. #67
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    I do not have to accellerate to keep my vertical speed constant (given no change in incline). Thus the angular velocity of my wheels do not change and it does not matter where the weight of my bike sits.

    What happens in that nasty hairpin that suddenly gives me 20% to battle instead of 6% is another story.

  18. #68
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    yes you have to do it, and that constantly.and you have to constantly accelerate your wheels and your bike,

    Off course this acceleration is "cancelled" by the gravity acceleration on the opposite direction so at the end you perceive no change, now you can wrongly perceive that there is no acceleration because you have constant speed. but this doesn't mean it is not there.

    But well this is basic dynamic physics, one day you will understand
    Quote Originally Posted by zank
    They're just bikes. Ride 'em in the rain, salt, snow and crap to fully appreciate them.
    Quote Originally Posted by Sean Kelly
    The thing about the cold is that you can never tell how cold it is from looking out a kitchen window. You have to dress up, get out training and when you come back, you then know how cold it is.

  19. #69
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    I know my dynamics.

  20. #70
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    Salsa is correct on all accounts on this but i think a lot of you guys are getting off base. First of tall, the guy who posted the pic of the dirt road, WTF dude, your on a CX bike. As salsa mentioned, we are discussing roadbikes that are primarily being ridden on decently paved roads. I'm a 240lb clyde and I agree, there really isn't much reason to put tires bigger than a 25 on a road bike UNLESS your heavy like I am. Alas, the frame design generally doesn't allow for anythign bigger than a 25 on an aggressively setup road bike. some of the comfort geometry road bikes like Giant Defy will let you fit 28's on them, maybe even 32's. I've actually ridden on a 21mm tubulars and it's not fun and i got a blowout really easy because at my weight i've got to run the pressure so damn high that a pothole easily wrecks it. The problem is i recently switched to tubulars and I love them but they don't make many in 25mm size so options are a bit limited.

  21. #71
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    Quote Originally Posted by motobecane69 View Post
    Salsa is correct on all accounts on this but i think a lot of you guys are getting off base. First of tall, the guy who posted the pic of the dirt road, WTF dude, your on a CX bike. As salsa mentioned, we are discussing roadbikes that are primarily being ridden on decently paved roads. I'm a 240lb clyde and I agree, there really isn't much reason to put tires bigger than a 25 on a road bike UNLESS your heavy like I am. Alas, the frame design generally doesn't allow for anythign bigger than a 25 on an aggressively setup road bike. some of the comfort geometry road bikes like Giant Defy will let you fit 28's on them, maybe even 32's. I've actually ridden on a 21mm tubulars and it's not fun and i got a blowout really easy because at my weight i've got to run the pressure so damn high that a pothole easily wrecks it. The problem is i recently switched to tubulars and I love them but they don't make many in 25mm size so options are a bit limited.
    Why don't you run 27mm Vittoria Pave tubulars? I would and I weigh 165.

  22. #72
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    Quote Originally Posted by Chris-X View Post
    Why don't you run 27mm Vittoria Pave tubulars? I would and I weigh 165.
    1. They won't fit
    2. I'd like to find a tire that doesn't cost $120!

    Don't get me wrong, if the ride quality is there, I'll ride them. honestly, I think i've hesitated on buying them because I hate that stupid green stripe down the middle of them that would absolutely clash with my bikes color scheme!

    What sucks is my lbs gave me a pair of conti competitions FOR FREE! but they are 21mm, I blew one out the first ride on them and tire alert is fixing it now. I'm hoping I can find someone that would trade me so I can get the 25mm version of those

  23. #73
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    what about

    Quote Originally Posted by motobecane69 View Post
    1. They won't fit
    2. I'd like to find a tire that doesn't cost $120!

    Don't get me wrong, if the ride quality is there, I'll ride them. honestly, I think i've hesitated on buying them because I hate that stupid green stripe down the middle of them that would absolutely clash with my bikes color scheme!

    What sucks is my lbs gave me a pair of conti competitions FOR FREE! but they are 21mm, I blew one out the first ride on them and tire alert is fixing it now. I'm hoping I can find someone that would trade me so I can get the 25mm version of those
    these

    FMB PARIS ROUBAIX TUBULAR

    TUBULAR TIRES

  24. #74
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    Quote Originally Posted by Chris-X View Post
    Off-topic question regarding these tires:

    Do these tires become stronger/better by aging them?


    I read Lance Armstrong raced on tires that were at minimum 5 Y.O.
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  25. #75
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    Quote Originally Posted by cda 455 View Post
    Off-topic question regarding these tires:

    Do these tires become stronger/better by aging them?


    I read Lance Armstrong raced on tires that were at minimum 5 Y.O.
    Yes

    Tubular Tires - Branford Bike - Seattle/Bellevue - Campagnolo Pro Shop

    How a handmade tubular is made - YouTube

    No

    Tubular Fables by Jobst Brandt

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