Jan MBA: "Tubless tires roll a gear faster in all conditions..."

Discussion in 'Cycling Equipment' started by x, Jan 22, 2003.

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  1. x

    x Guest

    Just came across this in the January issue of Mountain Bike Action. Page 19, "TUBE OR TUBLESS"

    The spiel is that, "...the tube causes the tire to roll slower due to internal friction,..." and
    "...tubless tires roll a whole gear faster in all conditions..." (than tubed).

    I'm having trouble with that assertion.

    First, a whole gear is a *lot* of friction and it would seem to me that competitive riders using
    tubless should have had a crushing advangage over others from day 1. i.e. Virtually all races should
    be won by people riding tubless. For all I know, this may be true....anybody know for sure?

    Second, it begs the question of why in the old, primative, pre-tubless, days (and even today...)
    really competative riders didn't/don't dust their tubes with some friction-reducing substance like
    graphite. In my experience, talc is sort of traditional - but more as a convenience to keep the tube
    from sticking to the casing and to reduce pinch flats by letting the tube find it's place easier
    when the tire is initially pumped up. If friction were such a big issue I'd expect to see the market
    littered with near-magical-seeming potions to reduce tub/casing friction.

    Comments?

    -----------------------
    Pete Cresswell
     
    Tags:


  2. Mark Hickey

    Mark Hickey Guest

    "(Pete Cresswell)" <[email protected]> wrote:

    >Just came across this in the January issue of Mountain Bike Action. Page 19, "TUBE OR TUBLESS"
    >
    >The spiel is that, "...the tube causes the tire to roll slower due to internal friction,..." and
    >"...tubless tires roll a whole gear faster in all conditions..." (than tubed).
    >
    >I'm having trouble with that assertion.

    You hit the nail on the head. I've read a lot of claims - some by very highly-respected techie types
    - that propose things that just don't make sense when subjected to the harsh light of common sense.
    This is one of 'em... "A whole gear faster" intimates at least 1mph
    (1.6km/h) increase in speed... or enough to propel anyone in the middle of the pack to the podium.

    I took exception to a couple aero aids that would have moved 1/3 the Tour de France field ahead of
    Lance on the stage 19 time trial in '02 as well.

    Or to put it another way, "if it was that good, no one could possibly race without it".

    Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame
     
  3. (Pete Cresswell) wrote:

    > Just came across this in the January issue of Mountain Bike Action. Page 19, "TUBE OR TUBLESS"
    >
    >
    > The spiel is that, "...the tube causes the tire to roll slower due to internal friction,..." and
    > "...tubless tires roll a whole gear faster in all conditions..." (than tubed).
    >
    > I'm having trouble with that assertion.
    >
    > First, a whole gear is a *lot* of friction and it would seem to me that competitive riders using
    > tubless should have had a crushing advangage over others from day 1. i.e. Virtually all races
    > should be won by people riding tubless. For all I know, this may be true....anybody know for sure?

    I don't believe it for a moment. Here's something I posted to aus.bicycle on this subject:

    > Jason King wrote:
    >
    >> I don't really notice all the lower rolling resistance that reviewers and website go on and
    >> on about,
    >
    > That's hardly surpising as bike and product reviewers tend to find what they expect to find, the
    > time and money to do meaningful double-blind tests being nonexistent in the bike media.
    >
    > Let's think about this one a little. Say you're doing 25 km/h, a not unfeasible speed on fairly
    > flat, smooth trails (and on any other kind you have way more to slow you down than rolling
    > resistance). At that speed, about 80 percent of your effort is going into overcoming air
    > resistance, the rest into various rolling friction resistances, of which tyre rolling resistance
    > is the biggest. Let's ignore trivia like bearing friction for the moment and say all that 20
    > percent is rolling resistance.
    >
    > A tyre/tube combination causes rolling resistance from three things: hysteresis losses when the
    > tyre flexes and straightens; hysteresis losses when the tube flexes and straightens; and ditto
    > from the tread squirming as it contacts and leaves the ground. The tyre accounts for the vast
    > majority of the losses, being thicker and stiffer than the tube.
    >
    > If we guesstimate that the tyre accounts for 90 percent of the rolling resistance, then it's
    > hardly surprising you can't feel any different when you lose the tube. It was only proving a
    > couple of percent of the resistance to the work you're doing. You might now be going a shade under
    > a couple of percent faster, but it's the difference between 25km/h and 25.5 km/h. You can measure
    > that, but I don't believe you can feel it.

    Now I freely admit my figures are hand-waving, but they feel about right. If someone has some Actual
    Data then we could nail this one. I may be out by a bit here and there, but I doubt I'm out the
    whole order of magnitude necessary to get to "a gear [10-15 percent on a mountain bike] faster"

    > Second, it begs the question of why in the old, primative, pre-tubless, days (and even today...)
    > really competative riders didn't/don't dust their tubes with some friction-reducing substance like
    > graphite. In my experience, talc is sort of traditional - but more as a convenience to keep the
    > tube from sticking to the casing and to reduce pinch flats by letting the tube find it's place
    > easier when the tire is initially pumped up. If friction were such a big issue I'd expect to see
    > the market littered with near-magical-seeming potions to reduce tub/casing friction.
    >
    > Comments?

    Tyre/tube friction is not that big an issue. I deliberately disregarded it in the analysis above
    because most riders don't faff about with talc and their tyres and tubes therefore stick together,
    reducing the friction to its most desirable level: zero.
     
  4. Don't believe everything you read.

    Ernie

    "(Pete Cresswell)" wrote:

    > Just came across this in the January issue of Mountain Bike Action. Page 19, "TUBE OR TUBLESS"
    >
    > The spiel is that, "...the tube causes the tire to roll slower due to internal friction,..." and
    > "...tubless tires roll a whole gear faster in all conditions..." (than tubed).
    >
    > I'm having trouble with that assertion.
    >
    > First, a whole gear is a *lot* of friction and it would seem to me that competitive riders using
    > tubless should have had a crushing advangage over others from day 1. i.e. Virtually all races
    > should be won by people riding tubless. For all I know, this may be true....anybody know for sure?
    >
    > Second, it begs the question of why in the old, primative, pre-tubless, days (and even today...)
    > really competative riders didn't/don't dust their tubes with some friction-reducing substance like
    > graphite. In my experience, talc is sort of traditional - but more as a convenience to keep the
    > tube from sticking to the casing and to reduce pinch flats by letting the tube find it's place
    > easier when the tire is initially pumped up. If friction were such a big issue I'd expect to see
    > the market littered with near-magical-seeming potions to reduce tub/casing friction.
    >
    > Comments?
    >
    > -----------------------
    > Pete Cresswell
     
  5. Ajames54

    Ajames54 Guest

    On Mon, 13 Jan 2003 01:25:56 GMT, "(Pete Cresswell)" <[email protected]> wrote:

    >Just came across this in the January issue of Mountain Bike Action. Page 19, "TUBE OR TUBLESS"
    >
    >
    >The spiel is that, "...the tube causes the tire to roll slower due to internal friction,..." and
    >"...tubless tires roll a whole gear faster in all conditions..." (than tubed).
    >
    >I'm having trouble with that assertion.
    >
    snip
    >
    no kidding!

    >Comments?
    >
    >-----------------------
    >Pete Cresswell

    hmmmm ....I wonder what makes them think that there is any loss in rolling speed due to "internal
    friction" is this some sort of energy sink I've never heard of?... I guess everyone in the TDF will
    be on tubeless next year...

    They should stick to pushing the weight savings since we all know that every gram of rotating weight
    = 3 burritos and a diet pepsi from taco bell ... Or was it equal to 50 million dollars in a nigerian
    bank? I can never remember...

    on the other hand we're talking about it and that is what they want.. that sells magazines and their
    sponsors love that...
     
  6. Matt O'Toole

    Matt O'Toole Guest

    "Mark Hickey" <[email protected]> wrote in message
    news:[email protected]...

    > "(Pete Cresswell)" <[email protected]> wrote:
    >
    > >Just came across this in the January issue of Mountain Bike Action. Page 19, "TUBE OR TUBLESS"
    > >
    > >The spiel is that, "...the tube causes the tire to roll slower due to
    internal
    > >friction,..." and "...tubless tires roll a whole gear faster in all conditions..." (than tubed).
    > >
    > >I'm having trouble with that assertion.
    >
    > You hit the nail on the head. I've read a lot of claims - some by very highly-respected techie
    > types - that propose things that just don't make sense when subjected to the harsh light of common
    > sense. This is one of 'em... "A whole gear faster" intimates at least 1mph
    > (1.6km/h) increase in speed... or enough to propel anyone in the middle of the pack to the podium.
    >
    > I took exception to a couple aero aids that would have moved 1/3 the Tour de France field ahead of
    > Lance on the stage 19 time trial in '02 as well.
    >
    > Or to put it another way, "if it was that good, no one could possibly race without it".

    Well, haven't you heard, no one can possibly race without tubeless tires...

    Matt O.
     
  7. Paul Hays

    Paul Hays Guest

    On Mon, 13 Jan 2003 5:18:22 -0800, E & V Willson wrote (in message <[email protected]>):

    > Don't believe everything you read.
    >
    > Ernie
    >

    Particularly in "Mountain Bike Action!" I've never thought of them as a bastion of critical
    reporting...
     
  8. Kinkycowboy

    Kinkycowboy Guest

    On Mon, 13 Jan 2003 08:18:22 -0500, E & V Willson <[email protected]> wrote:

    >Don't believe everything you read.
    >
    >Ernie
    >
    >"(Pete Cresswell)" wrote:
    >
    >> Just came across this in the January issue of Mountain Bike Action. Page 19, "TUBE OR TUBLESS"
    >>
    >> The spiel is that, "...the tube causes the tire to roll slower due to internal friction,..." and
    >> "...tubless tires roll a whole gear faster in all conditions..." (than tubed).
    >>
    >> I'm having trouble with that assertion.

    >> Comments?
    >>
    >> -----------------------
    >> Pete Cresswell

    It shouldn't be too hard to prove whether tubeless tyres have lower rolling resistance, all you need
    is a set of SRM power cranks or similar and a bike with UST tyres to which you add tubes for half of
    your test laps. I doubt whether MBA did that, so its a subjective view from a rider who had read the
    labels on his tyres. A subjective assesment of a tyre in a comparitive test can be a legitimate way
    of judging between tyres over the full range of performance indicators, but I doubt that anybody
    could reliably differentiate between, say, the Conti Explorer Pro with a lightweight tube and the
    Conti Explorer Pro UST tubeless if same size tyres at the same pressure were mounted on two
    otherwise identical bikes. This from somebody who has spent his own money on UST wheels and tyres,
    and will do so again. There are some good reasons to go tubeless, but I doubt if reduced rolling
    resistance is one of them.

    Kinky Cowboy

    *Your milage may vary Batteries not included May contain traces of nuts.
     
  9. Paul Hays

    Paul Hays Guest

    On Mon, 13 Jan 2003 15:29:35 -0800, Scribe2b wrote (in message
    <[email protected]>):

    >> Particularly in "Mountain Bike Action!" I've never thought of them as a bastion of critical
    >> reporting...
    >
    > richard cunningham wrote the comments on tubeless. do you really think he's a shill? he always
    > seems straight to me. in any case i would think the Wombat connection speaks for itself too.
    >
    > jc

    Perhaps they've had an editorial turn-around. I stopped reading MBA years ago... Their gushing
    reviews of all new tech has been off-putting.

    As to the Wombat connection, I'm not sure what you're refering to. Does MBAction have a relationship
    with Wombat beyond Cunninghams personal relationship with J. Phelan, and if so, how does that
    reflect upon MBAction's propensity towards hype?
     
  10. On the contrary, there have been a number of MTB tire RR tests (albeit mostly with slicks or
    semi-slicks):

    http://www.physics.helsinki.fi/~tlinden/rolling.html http://legslarry.crosswinds.net/tech/GS.htm

    Also, look at some of the HPV publications. Apparently, the 26" size is popular with them.

    -- Jens

    "Matt O'Toole" <[email protected]> wrote in message
    news:p[email protected]...
    >
    > I always thought it would be interesting to put a bunch of MTB tires on a tire testing machine, as
    > has been done with road tires in the past. To my knowledge, no one ever has.
    >
    > Matt O.
     
  11. John Albergo

    John Albergo Guest

    (Pete Cresswell) wrote:

    >Just came across this in the January issue of Mountain Bike Action. Page 19, "TUBE OR TUBLESS"
    >
    >
    >The spiel is that, "...the tube causes the tire to roll slower due to internal friction,..." and
    >"...tubless tires roll a whole gear faster in all conditions..." (than tubed).
    >
    >I'm having trouble with that assertion.
    >
    >First, a whole gear is a *lot* of friction and it would seem to me that competitive riders using
    >tubless should have had a crushing advangage over others from day 1. i.e. Virtually all races
    >should be won by people riding tubless. For all I know, this may be true....anybody know for sure?
    >
    >Second, it begs the question of why in the old, primative, pre-tubless, days (and even today...)
    >really competative riders didn't/don't dust their tubes with some friction-reducing substance like
    >graphite. In my experience, talc is sort of traditional - but more as a convenience to keep the
    >tube from sticking to the casing and to reduce pinch flats by letting the tube find it's place
    >easier when the tire is initially pumped up. If friction were such a big issue I'd expect to see
    >the market littered with near-magical-seeming potions to reduce tub/casing friction.
    >
    Which "whole gear" are we talking about? Since air drag increases exponentially with airspeed, when
    you're in the higher gears the amount of energy spent on rolling resistance is nothing compared to
    air resistance. The rolling resistance of a decent smooth tire properly inflated is not much as you
    can see for yourself by coasting at slow walking speed. (A knobby mtb tire will slow you down but
    that's not because of the tube.) You'll go quite a ways - obviously the tires aren't eating a lot of
    energy. So even if these magic tires reduced this small rolling resitance to zero the effect would
    be negligible at speed. It's precisely in a race where the benefit would be smallest.

    Lubricating the tube won't help, the energy is spent in flexing the material not rubbing against the
    tire casing. Otherwise, tubes would quickly wear out from chafing inside the tire. By the way, the
    talc thing is bogus too. I used to go through that routine until I read here that it's hogwash. I
    haven't used talc since and have had no problems. Mounting is just as easier if not easier, and
    while the tube does adhere to the casing, it doesn't permanently bond to it - a tug always works.
     
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