Contact patch of 650b tyre

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  • Contact patch of 650b tyre
  • cbmotorsport
    Member

    Apologies for yet another wheel size related post, please post your ‘Oh no, not again, please make it stop’ posts below, if you feel the need. But…

    I picked up one of the MTB magazines in a supermarket the other day and while not buying it, I read a review on a tyre which wasn’t overly favourable. At the end of the review they stated that ‘reports on these tyres in 650b and 29″ guise are more positive due to the extra grip offered by the larger contact patch’.

    I was fairly gobsmacked at the utter twaddle I was reading, I’m no maths expert, but the size of the contact patch on a 650b can’t be large enough over a 26″ to offer any noticeable difference?

    Premier Icon roverpig
    Subscriber

    The size of the contact patch has more to do with the pressure in the tyre (and your weight) than the diameter of the wheel. If the contact patch is larger with a 650b or 29er then it’s most likely to be either due to the bike being heavier or the tyre pressures being lower.

    Now contact patch shape; that’s a different matter.

    cbmotorsport
    Member

    roverpig – Member

    The size of the contact patch has more to do with the pressure in the tyre (and your weight) than the diameter of the wheel. If the contact patch is larger with a 650b or 29er then it’s most likely to be either due to the bike being heavier or the tyre pressures being lower.

    Now contact patch shape; that’s a different matter.

    My thoughts exactly, which is why the article was a load of crap.

    Premier Icon sheck
    Subscriber

    MTB magazine in “utter twaddle” shocker…

    mrmo
    Member

    Now contact patch shape; that’s a different matter.

    which between 26 and 650b is barely different because they are so close in size.

    I wonder what next seasons must have will be and what stadard will be ditched?

    Maybe super-oversized taper headsets, 22mm through axles, and 137mm of front end travel, think of the extra stiffness, that 16% less deflection* riding through a rock garden composed of 9.8″ baby heads.

    .
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    ..
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    ..

    *compared to a rigid ritchey logic unicrown fork with a qr the rider forgot to do up.

    cbmotorsport
    Member

    sheck – Member

    MTB magazine in “utter twaddle” shocker…

    Aye, it was a shocker. I don’t read ’em as a general rule so haven’t come across this level of hype before.

    Premier Icon al
    Subscriber

    You want to read the Banshee blog, it spoke some sense on wheel size physics. Not much sense, but some…

    There’s a MASSIVE difference – look, here they are, overlaid (assumes slick tyre and flat ground)

    From this series of articles, some interesting points made, whether you agree or not.

    http://www.nsmb.com/educating-the-debate-part-i/
    http://www.nsmb.com/educating-the-debate-part-ii/
    http://www.nsmb.com/educating-the-debate-part-iii/

    Premier Icon swavis
    Subscriber

    So if more is better why not just stick with the 29″? 😉

    Premier Icon Normal Man
    Subscriber

    Which mag? Name and shame time 😉

    That pic above – 2cm extra contact patch for a 1″ increase in diameter – that’s utter, utter bullshit.

    cbmotorsport
    Member

    Normal Man – Member

    Which mag? Name and shame time

    What Mountain Bike

    bikeneil
    Member

    swavis – MemberSo if more is better why not just stick with the 29?

    ^ this ^

    TurnerGuy
    Member

    That pic above – 2cm extra contact patch for a 1″ increase in diameter – that’s utter, utter bullshit.

    Giant in marketing bullsh1t shocker…

    Premier Icon Creaky
    Subscriber

    More contact patch = more drag, no? So it’s “scientifically proven” that bigger wheels are slower.

    SSBonty
    Member

    You can even see from the Giant ad pic that the 29er ‘contact patch’ below the tyre is overhanging the actual contact considerably…

    Premier Icon Northwind
    Subscriber

    Is it Made Up Bullshit, or is it just them taking a perceived difference and attaching an unconvincing reason? (ie, is the difference made up, or is it just the explanation for the difference that’s made up)

    Creaky – Member

    More contact patch = more drag, no?

    No.

    Sancho
    Member

    Make them stop mummy

    Utter bollox –

    Premier Icon Jon Taylor
    Subscriber

    Another thread on marketing bollox? Run!

    Ramsey Neil
    Member

    Apologies for yet another wheel size related post, please post your ‘Oh no, not again, please make it stop’ posts below, if you feel the need. But…

    I picked up one of the MTB magazines in a supermarket the other day and while not buying it, I read a review on a tyre which wasn’t overly favourable. At the end of the review they stated that ‘reports on these tyres in 650b and 29″ guise are more positive due to the extra grip offered by the larger contact patch’.

    I was fairly gobsmacked at the utter twaddle I was reading, I’m no maths expert, but the size of the contact patch on a 650b can’t be large enough over a 26″ to offer any noticeable difference?

    Not twaddle at all , common sense tells you that bigger wheels have a bigger contact patch so more grip , try a 26″ wheeled bike and then a 29er , there is a very noticeable difference .

    Premier Icon kelvin
    Subscriber

    I was fairly gobsmacked at the utter twaddle I was reading, I’m no maths expert, but the size of the contact patch on a 650b can’t be large enough over a 26″ to offer any noticeable difference?

    Note that he’s talking about 650b and 26″ tyres.

    Not twaddle at all , common sense tells you that bigger wheels have a bigger contact patch so more grip , try a 26″ wheeled bike and then a 29er , there is a very noticeable difference .

    You’re comparing 29″ and 26″ tyres.

    cbmotorsport
    Member

    Quite. I might have accepted the fact that 29″ offered a little more grip than 26″, but 27.5???

    Premier Icon tenfoot
    Subscriber

    Having ridden 27.5 650B and 26, I can say that I can’t tell the difference.

    shifter
    Member

    [video]http://www.youtube.com/watch?v=WdrskvNzPTE[/video]

    😛

    Premier Icon tenfoot
    Subscriber

    Seen it all now

    Premier Icon roverpig
    Subscriber

    Of all the tosh that get bandied about in the endless wheelsize debates the stuff on contact patch must rank as the most pointless. In most practical situations there is a trade off between grip and drag and you can find the sweet spot for any conditions by changing tyres and tyre pressures regardless of what size wheels you have.

    cynic-al
    Member

    Neil Ramsay, please don’t rely on your “common sense”.

    Try some O level physics: the contact patch area depends on pressure alone.

    Ramsey Neil
    Member

    Neil Ramsay, please don’t rely on your “common sense”.

    Try some O level physics: the contact patch area depends on pressure alone.

    O level physics was one that I actually got ,a long time ago I will grant you .

    You are of course totally wrong . Are you suggesting that a fat bike tyre would have a smaller contact patch than a 12″ kids tyre if it was run at a higher pressure ?

    Ramsey Neil
    Member

    Of all the tosh that get bandied about in the endless wheelsize debates the stuff on contact patch must rank as the most pointless. In most practical situations there is a trade off between grip and drag and you can find the sweet spot for any conditions by changing tyres and tyre pressures regardless of what size wheels you have.

    What you say is true but on a ride where you will ride through varying terrain , ground conditions and gradients you would be stopping to change tyres or tyre pressure every 5 mins if you wanted the ideal tyre and pressure which obviously isn’t practical . It’s always going to be a compromise , many feel that bigger wheels and tyres are better all rounders than 26″ .

    Premier Icon kelvin
    Subscriber

    Well, you can easily change your tyre pressure on a ride.
    See that valve? You can let air in and out of there quite easily.

    You can also change your tyres for different rides far more easily (and more cheaply) than you can change wheel size.

    Ramsey Neil
    Member

    Sorry , I like to ride my bike when I go out for a ride not stop every 5 minutes to adjust my tyre pressure . When I get home from that ride I like to clean the bike and put it away until the next time . I certainly don’t want to be thinking where is my next ride going to be and what tyres should I put on for it ?

    You are of course totally wrong . Are you suggesting that a fat bike tyre would have a smaller contact patch than a 12″ kids tyre if it was run at a higher pressure ?

    In a static situation if the situation isn’t being skewed by sidewall behaviour or the rise in pressure under load, then yes.

    Anyone claiming that one size is conclusively better than another doesn’t know what they’re talking about. There are pros and cons to everything!

    Ramsey Neil
    Member

    Anyone claiming that one size is conclusively better than another doesn’t know what they’re talking about. There are pros and cons to everything!

    I don’t think anybody at any time in this thread has claimed that .

    Premier Icon kelvin
    Subscriber

    I certainly don’t want to be thinking where is my next ride going to be and what tyres should I put on for it ?

    This whole thread is about “tyres”, so stop wasting your time here if you don’t want to think about them.

    Changing tyres is easier than changing wheelsize, and it’s effective, but it doesn’t sell new bikes.

    cynic-al
    Member

    Ramsey Neil – Member

    You are of course totally wrong . Are you suggesting that a fat bike tyre would have a smaller contact patch than a 12″ kids tyre if it was run at a higher pressure ?

    Of course it would be, as I said above, basic physics.

    cynic-al – Member

    Of course it would be, as I said above, basic physics.

    Think your physics are being a bit too basic here. If you were dealing with perfect, circular wheels that didn’t deform in contact with the ground and had identical curved profiles, then yeah. But realistically a fatbike tyre will have a much squarer profile, and a wider contact patch, even if pressure/deformation etc are all equal.

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