Bits on tyres

chedabob
chedabob Posts: 1,133
edited September 2010 in MTB general
What are the little spindly bits on the tread of Conti tyres for?

frxM7.jpg

Some of them have them on the sidewall too, and it's not just Conti that have them.

Comments

  • nicklouse
    nicklouse Posts: 50,675
    nothing.

    just part of the manufacturing process.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Anonymous
    Anonymous Posts: 79,667
    they are there to show how girly youare. if they arent all worn own, you havent been cornering hard enough.

    my tyres always have those spikes on the edges :wink:
  • Atz
    Atz Posts: 1,383
    It's the bit where the rubber is injected.
  • Anonymous
    Anonymous Posts: 79,667
    Atz wrote:
    It's the bit where the rubber is injected.

    must resist.
  • Raymondavalon
    Raymondavalon Posts: 5,346
    sheepsteeth wrote:
    Atz wrote:
    It's the bit where the rubber is injected.

    must resist.
    :D:D:D:D:D:D
    The Bouncer
    The Shaker
  • MTB Nut
    MTB Nut Posts: 46
    sheepsteeth wrote:
    Atz wrote:
    It's the bit where the rubber is injected.

    must resist.

    Fuelled by Johnnie Walker Whiskey just woke my lass up laughing like a idiot.

    ROFL :lol:
  • weescott
    weescott Posts: 453
    MTB Nut wrote:
    sheepsteeth wrote:
    Atz wrote:
    It's the bit where the rubber is injected.

    must resist.

    Fuelled by Johnnie Walker Whiskey just woke my lass up laughing like a idiot.

    ROFL :lol:


    I wouldn't admit to ticking the sides on a forum TBH!
  • PXR5
    PXR5 Posts: 203
    Right, at the risk of being later proved wrong wrt the manufacturing process of tyres I will now enlighten you on some of the more technical terms used in the injection moulding process...

    These words however should not be taken lightly, and it is highly likely that some posters (sheepsteeth) will find them amusing...

    Right firstly those nobbly bits, I wouldn't have thought they were where the rubber is injected, rather they are air vents to allow air our of the mould, and the rubber to fill all the tread pattern correctly, you don't want air bubbles instead of rubber..

    You need good VENTING

    The word for the excess/wasted material is FLASH

    Good FLASH is usual to ensure proper mould filling, excess Flash is wasted material

    See that slight line that runs all the way around the centre of the tyre, its where the two halves of the mould join together, this is know as THE SPLIT LINE..

    This is probably already too much information for some on the forum, so i'm off for me lunch...
    Every time I go out, I think I'm being checked out, faceless people watching on a TV screen.....
  • stumpyjon
    stumpyjon Posts: 4,069
    At the risk of spoiling the double entendres rubber is not injected into a mould to make tyres. The tyre is made up of long strips of rubber produced on an extruder. The rubber is then wrapped around rubber bladder which is then inflated to give the tyre shape. This virgin tyre is then placed into the mould. Another rubber bladder is inflated inside the tyre in the mould intimately pressing the rubber into the crevesies in the mould to form the tread.

    Tyre-Duplex-Extrusion-Line.jpg

    A very clever extruder that can do two different types of rubber at the same time.
    It's easier to ask for forgiveness than for permission.

    I've bought a new bike....ouch - result
    Can I buy a new bike?...No - no result
  • blister pus
    blister pus Posts: 5,780
    so there
  • PXR5
    PXR5 Posts: 203
    Thanks stumbyjohn for putting me right...

    Now this extruder, what screw profile would be typical ???

    :wink:
    Every time I go out, I think I'm being checked out, faceless people watching on a TV screen.....
  • chedabob
    chedabob Posts: 1,133
    stumpyjon wrote:
    At the risk of spoiling the double entendres rubber is not injected into a mould to make tyres. The tyre is made up of long strips of rubber produced on an extruder. The rubber is then wrapped around rubber bladder which is then inflated to give the tyre shape. This virgin tyre is then placed into the mould. Another rubber bladder is inflated inside the tyre in the mould intimately pressing the rubber into the crevesies in the mould to form the tread.

    Tyre-Duplex-Extrusion-Line.jpg

    A very clever extruder that can do two different types of rubber at the same time.

    Then what are the sticky out bits if they're not the injection points? And why do only some manufacturers have them and not others? Even different models of the same tyre omit them.
  • Miggins
    Miggins Posts: 433
    sheepsteeth wrote:
    Atz wrote:
    It's the bit where the rubber is injected.

    must resist.

    Sheepsteeth, that's not you getting all excited about rubber again, is it? ( http://www.bikeradar.com/mtb/forums/vie ... highlight=) whip.gif
    After uphill there's downhill
  • stumpyjon
    stumpyjon Posts: 4,069
    PXR5 wrote:
    Thanks stumbyjohn for putting me right...

    Now this extruder, what screw profile would be typical ???

    :wink:

    Well actually your average extruder can have two different screws, the extruder screw and a plastifier screw which is like a secondary extruder.....

    Anyone still awake?

    No idea what the little spikey bits are for, I worked in a Michelin factory for 4.5 years but as you might have guessed I worked at the extrusion end not the curing end. Now have I mentionned calanders yet (not the papery date variety) :roll:
    It's easier to ask for forgiveness than for permission.

    I've bought a new bike....ouch - result
    Can I buy a new bike?...No - no result
  • Anonymous
    Anonymous Posts: 79,667
    The spikey bits are girly-meters, obviously. DUH. Same as those grinding pegs you can get for motorcycle footpegs.
    You can buy tyres without them if you're too much of a girl to ever eliminate them.

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