Clinchers vs Tubulars information sought

Discussion in 'Cycling Equipment' started by kisertn, Dec 2, 2013.

  1. kisertn

    kisertn New Member

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    First, I am aware this is a well-worn topic. I have spent the last hour combing through posts to see if I could find what I was seeking. And that's after more time spent this past weekend doing the same. No luck however.

    I am after something specific and so I hope this will be a bit more targeted.

    First:
    - I have no problems with any differences in handling a tubular flat or a clincher flat - non-issue for me (in my mind anyway :)
    - I have no issues over cost differentials between clinchers and tubulars
    - I have no problem changing my brake pads as I switch from one type of rim to the other if needed.

    In the end, I know clinchers (don't we all), but I do not know tubulars. I am contemplating tubulars ONLY because of the impression I have that they may be more performant than clinchers in race conditions. My perceptions are not based on the tire itself, but rather on the lighter weight, and in particular the fact that clinchers have their additional weight at the rim. The specific performance gain being the ability to accelerate more quickly (or at least with lessened effort) during a race.

    If I were to be convinced that tubulars offered me no appreciable performance gains then I would see no reason to consider them. So my question goes out to those who race with tubulars: do you feel that tubulars give a noticeable and significant performance advantage over clinchers in a race? (in particular criteriums).

    Thank you for any feedback,
    -Neil
     
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  2. CAMPYBOB

    CAMPYBOB Well-Known Member

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    "do you feel that tubulars give a noticeable and significant performance advantage over clinchers in a race? (in particular criteriums)."

    Noticeable? Yes. Significant? ANY advantage in competition is 'significant'.

    Wheel for wheel, the sew-up is lighter. Generally speaking, they stick better.












    Queue the tard in 3...2...1...
     
  3. alienator

    alienator Well-Known Member

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    When you talk about weight distribution in a wheel or how wheels accelerate, you need to talk about moment of inertia, a measure of how mass is distributed, in this case, around an axis as well as a measure of the inertia (resistance to change in motion) that a wheel has. Since the only thing you'll really be changing is the mass of the wheel, the change in moment inertia is just going to be equal to the change in weight divided by the previous wheel weight. If you're using a clincher setup that weighs 2250g and you switch to a tubular setup that weighs 400g less then you're wheels' moment of inertia will be 17.8% less. As a result the torque and power required to accelerate that wheel set a specified amount will be 17.8% less.......which sounds great. Unfortunately, the actual benefit, once you factor in all of the other forces that have to be overcome to accelerate a bicycle, is pretty small. Read the analysis done at this link to see how big the changes in wheel acceleration are when moment of inertia is changed. Note that in that analysis, huge changes in wheel MOI are used. With that said, an argument could be made for using heavier wheels in order to carry speed over the cobbles. Frankly, your position on the bike and the associated aero drag will have a much bigger effect than the MOI of your wheels. I think the best option is no matter what tires you use, use the widest tire that you can fit. A large air volume in a tire will do more to prevent flats and to minimize the beating and the resulting fatigue you'll suffer from the cobbles. I think I'd fit a 28mm tire if I could get that to fit. I certainly wouldn't use less than a 25mm, but I think the 28mm would be optimal. Wide rims will help as they increase the air volume for a given size tire. My inclination is to say, "ride what you know, " which would be the clinchers. A tire like a 28mm Continental GP 4 Seasons would get you through such a ride as would a tire like Vittoria's 27mm Open Pavé CG. If you end up using tubulars, the only one I'd consider would be Vittoria's 28mm Pavé. As for the performance advantages between tubulars and clinchers, well, that's a religious debate. It's certain that there's not a lot that separates the best tubulars and the best clinchers now. There's no clear evidence that one is superior to the other, thus my suggestion that you use what you know. I've used both and have found the differences between them small.
     
  4. WillemJM

    WillemJM New Member

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    I'm just a simple Engineer, but do not agree with the wider tire theory. In this case other than rolling resistance, moment of inertia is also the enemy.

    When it comes to tires, rolling resistance is most important and here is an interesting article in Velo. Scroll down to the table, and read the article.

    http://velonews.competitor.com/2007/06/bikes-and-tech/technical-faq/technical-qa-with-lennard-zinn-rolling-resistance_12493


    If I was Eric Zabel, I would ride a tubular.

    If I was Chris Froome, I would be on clinchers.
     
  5. alienator

    alienator Well-Known Member

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    You might want to see the link I included above that analyses how changes in moment of inertia affect acceleration.
     
  6. WillemJM

    WillemJM New Member

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    Sorry, I missed the link. I do not see the relevance though? We all know a disc is an advantage in a time trial, but a great disadvantage in a sprint.

    From the author, there sure are easier ways to demonstrate flywheel effect, than using a 4th order Runge-Kutta numerical differentiation.
     
  7. alienator

    alienator Well-Known Member

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    There are, but that does not change anything. The numbers MarkMcM got don't lie, It is certain that people are not accurate sensors. That's why there's a scientific method. Further, quantify "great disadvantage in a sprint." There is no disconnect between the numbers and reality. There might be other factors--one being that the model he chose for a wheel, a thin ring, influences the solution such that it overemphasizes the effect of MOI. mR2 is absolutely not the actual MOI of any bicycle wheel and that includes spoked wheels. It is the use of an MOI of mR2 that allows Mark McM to say that wheel mass is just twice static mass. Again, that causes the effects of MOI to be exaggerated (whether that's a lot or a little depends on the wheel/tire/tube combination in question). The take-home point of Mark McM's analysis is that giant differences in MOI result in only small changes in acceleration. To show you an example of how the mR2, I used data from an article Leonard Zinn wrote for Velo ( http://velonews.competitor.com/2008/07/bikes-and-tech/calculating-a-wheel’s-moment-of-inertia_157317 ) in which he measured the MOI of 12 wheels to show how far the actual MOI is from the theoretical of mR2. [IMG ALT=""]http://www.cyclingforums.com/content/type/61/id/294669/width/500/height/1000[/IMG] In the above table columns A-E are as follows:
    • Wheel make and model
    • Mass of the wheel as measured by Zinn
    • MOI of wheel as measured by Zinn
    • What the wheel's diameter would have to be if mR2 was the actual MOI for the wheel
    • What the MOI for the wheel would be using the measured mass and the standard 700c diameter of 622mm (Mark McM's assumption)
    • The percent ratio of the theoretical MOI to the real MOI
    Note how column D, the theoretical rim diameter if mR2 was the actual MOI, shows that the mass in the wheels is not biased toward the rim but toward the hub compared to the theoretical MOI. Note that none of this addresses what a rider feels. What a rider feels will be unique to that rider's assumptions/presumptions, how that rider interprets stimuli, that rider's state of mind, the rider's health, and other factors that are known to introduce bias into seat of the pants observations. A given rider might perceive some difference between two wheels, but what that rider perceives and the magnitude of what that rider perceives may have no correlation with reality. As for a disc wheel, its MOI would very closely match its theoretical MOI which is 0.5mR2, which means that it would have response nearly identical to that of non-rotating mass on a bike, at least when it comes to acceleration. Note that I'm not being argumentative at all. I think this is a good discussion to have.
     
  8. dabac

    dabac Well-Known Member

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    Yeah, humans can be quite good at detecting change, but often absolute rubbish at setting numbers to it. When I go from narrow summer slicks to studded winter tires on the commuter I'm close to doubling the weight of the tires. By feel the bike becomes amazingly sluggish in pretty much everything but steady speed forward. If I'd been asked to guess I'd probably think I'd be going 25-30% slower. The real number? 10% I can be faster on studs when there's a suitable rider to chase or keep ahead of, than I might be on a "casual" slicks ride. I think a German road bike mag did a rolling resistance test where (some) clinchers did better than tubulars. Might be able to dig it up. The consensus on the local bike site isn't much about speed any more, but more about tubulars "feeling" nicer, and leaves you with a bigger chance of retaining control in case of a sudden flat. MTB tubulars rules the roost for riding with really low pressures and keeping the tire both on and inflated.
     
  9. WillemJM

    WillemJM New Member

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    Alienator, that is a very complex analysis applied to an extremely simple concept. If Eric Zabel had to sprint the final 100 meters against his exact imaginary twin and accelerate from 38 km/h to 55km/h and his twin had an advantage of 100 grams per rim only, without doing the math I already know who would cross the line first. Does it matter whether by 1m or 100mm? In racing every one wants to sit around number 10 in the bunch so it ends up in a game of constant acceleration and deceleration. Every watt counts. I am sitting at Detroit Airport on my phone, but if you still differ let me know and I will do the math when more convenient.
     
  10. CAMPYBOB

    CAMPYBOB Well-Known Member

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    "Alienator, that is a very complex analysis applied to an extremely simple concept."

    I keep asking him 'why' we have a category of velocipedes referred to as "lightweight" bicycles. Ever wonder why we've never seen a scientist win the Tour of France on a heavy bike?

    Weight matters. All weight matters. All the time.



    "it ends up in a game of constant acceleration and deceleration. Every watt counts."

    [scientist]But...but...but, you just don't understand!!! Every Watt is returned!!! Accelerations and decelerations cancel each other out!!! In mathematics it's a closed system!!! The flexible frame RETURNS its energy to you!!![/scientist]

    Yeah, I'm just an engineer, myself. But, I've raced a metric shit ton of crits and I've never seen someone 'coast' past me during one of those mythical heavy wheel moment of inertia energy returns the scientist keeps calculating.


    "I am sitting at Detroit Airport..."

    You poor bastage! [​IMG] Do work for the auto industry? My last foray into the car biz involved landing on the ice skating rink GM called Big Beaver Airport in Pontiac. Taking off in a Mitsu corporate turboprop, in a blizzard, headed right for a 4-story tall assembly plant at the end of the runway...interdasting!
     
  11. alienator

    alienator Well-Known Member

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    Actually the analysis isn't that complex given the model Mark McM used. The model can be adapted to use realistic values to reveal more accurate results. In fact, if you have accurate information you can get much of the detail from AnalyticCycling.com. Your example assumes that all else is equal which means each has exactly the exact same air flow and turbulence characteristics over whatever distance they sprint and that they both experience the exact same changes in Crr as a result of variances in the road surface, an assumption which may not hold. Rather I think that Crr as the result of variance in road surface detail. At best, any road Crr would likely be most accurately modeled with some uncertainty, C ± ε, in which case the uncertainty could be such that the difference that 100g would make would be lost in the uncertainty. For any realistic situation, the uncertainty only grows with the increased number of variables that cannot be constrained. I base that assumption on my work in developing new methods for characterizing surface figure (a measure of the difference between the theoretically perfect surface and the real surface being characterized) of large optical surfaces (up to 4m diameter). I will grant you that it is the nature of racing to use every possible advantage, whether or not that advantage is real or detectable.
     
  12. WillemJM

    WillemJM New Member

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    LOL Use to work in the auto industry as an Engineer for Mercedes in Deutchland. Jumped ship though, all that remains are good memories. Truth be said, due to work and age the watts from my legs have decreased to a disadvantage so big it makes the improvement from high priced light components insignificant. These days the goal is to pray for short hills and hanging in the bunch for as long as possible. I may just try and swap the wheels from my Hayabusa to my Colnago to test the MOI theory this week-end. (Joke)
     
  13. CAMPYBOB

    CAMPYBOB Well-Known Member

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    "I may just try and swap the wheels from my Hayabusa..."

    Similar lifestyles. I had a GSXR-1100. It was a wonderful bike, but I knew it was going to get me killed. Sold it and kept the Harleys and Indian. Slow and steady...with lots of storage space!
     
  14. WillemJM

    WillemJM New Member

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    Bet you miss the GSXR-1100?

    We can never have enough things on two wheels.[​IMG]

    Just respect the power, mine still scares the bejebers out of me if I twist the throttle anything below 4th gear.

    Getting that front wheel to fit the Colnago fork is going to be a challenge, any ideas?

    [​IMG]


    Way back in the mid 90's I got into a math debate with Jobst Brand about power lost due to an unbalance bicycle wheel. I think it ended with him wanting to check my math by textbook reference and with me getting a decimal point totally wrong in a metric unit. Sigh, then we grow older and wiser. I still put my wheel magnet opposite the valve stem though.[​IMG]
     
  15. swampy1970

    swampy1970 Well-Known Member

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    Ah, so that's why EVERY top track sprinter uses a disk...
     
  16. swampy1970

    swampy1970 Well-Known Member

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    I'd fancy your chances of staying alive by just laying off the throttle on the GSXR and accelerating like a broken down Yugo running on one cylinder with a fouled spark plug and seized brakes Harley.
     
  17. WillemJM

    WillemJM New Member

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    Swampy, have you raced on an indoor wooden track?

    You think it is the same as a road lead out, followed by a final stage sprint?
     
  18. swampy1970

    swampy1970 Well-Known Member

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    Rules state you can't use a disk in a mass start road event. On the track you see disks used in pretty much every event from the sprint, the team sprint (1km TTT with 3 guys per team) to the individual kilo and all the way upto the keirin (but not the keirin in japan) and points race. On some of the less steep hillclimbs in England, some of the lads back in the early 90s used the flat Zipp 950 disk with a fixed gear. Very stiff and the weight didn't seem to be too much on an issue unless the grades went over 10% I've ridden the track a few times for fun and just about left the contents of my stomach plastered all over the track when my coach once bet I couldn't beat 1:20 for the kilo.
     
  19. CAMPYBOB

    CAMPYBOB Well-Known Member

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    "laying off the throttle on the GSXR"

    [​IMG]



    "and accelerating like a broken down Yugo running on one cylinder with a fouled spark plug and seized brakes Harley."

    Even my 1947 FL will get you deaded in mere seconds. Lightning cam, the biggest faucet Linkart ever built, close ratio ratchet top, straight pipes and enough torque to shear every rivet on the rear wheel sprocket!

    Sadly, it's still like paint drying compared to a liter sport bike. [​IMG]
     
  20. 531Aussie

    531Aussie Well-Known Member

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    Can someone dumb down all that "rotating mass" tech talk for me, and sum it up in a couple of sentences?


    I've said this a dozen times on a dozen forums, but......

    When I first heard a guy talking about his 150g lighter rims spinning up faster, I though it he was joking, and all these years later, I still think it's a joke. I think I said something to him like: "they're not gunna be 'suddenly spinning up' anywhere, because the tyres are stuck on the road, being held down by all you're weight, which you've still got haul up the road. The wheels will be 'waiting' for you to eventually get all your weight moving along, so they might be able to spin at a good speed"

    The only time external rotating rim/tyre mass makes a difference to accelerating a bike wheel is when the bike is on a stand, or a trainer with little resistance. :)

    The fastest-feeling wheel I have are my 2.140kg DT RR 1.2s; I suspect because they're very stiff.

    If extra external rotating mass did get to a point that it could make a tiny difference in accelerating a bike, then I figure the difference, if any, would be due to the extra weight adding to the total load that must be moved along, or up, the road.
     
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