Recent stem purchase

jquach
jquach Posts: 29
edited June 2014 in MTB general
I was looking into buying a new stem to go with my on-one carbon bars and come across this on ebay, £21.97 inc delivery. Copy of Renthal Strata Duo MTB Stem, installed with no problems but have yet to take my bike out on a ride. Anyone else using this stem?

TMCSTEM_zps76ae7ac4.jpg

Original

p5pb8566036.jpg

Comments

  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    I don't think I would want a fake stem. When that breaks your face will be a mess!
    The genuine Renthal stem was too flexy for me even with their fancy forging process.
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  • njee20
    njee20 Posts: 9,613
    Is it a copy, or is the Renthal an open mould product which other brands are sticking their logo on? A la Superstar.

    Edit: looks like a copy. It's a no from me.
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    It's certainly not genuine. The real thing is forged and cnc finished. That looks die cast which is much weaker than forging but lighter. Forging compresses the material in to shape under extreme pressure which increases density and creates some excellent mechanical properties.
    Die casting is just pouring molten aluminium in to a mould. Considerably weaker with inconsistent mechanical properties but less dense so lighter.
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  • warpcow
    warpcow Posts: 1,448
    Didn't Renthal buy the design from a German company (Foride?) originally?
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  • The Rookie
    The Rookie Posts: 27,812
    RockmonkeySC wrote:
    Die casting is just pouring molten aluminium in to a mould.
    No, that's casting, Die casting is different.......
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    In very basic terms it's just metal poured in to a mould, there's a little more to it but not much. It is under pressure, but not huge pressures.
    Transition Patrol - viewtopic.php?f=10017&t=13070235
  • The Rookie
    The Rookie Posts: 27,812
    No in very basic terms it's molten metal pumped or forced into a mould, that is why it's die casting and not casting, it can be low or high pressure (LPDC or HPDC).
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    Pressures compared to forging are very low.
    It's not the best process if you want high quality components with good control of mechanical properties.
    A die cast stem will be a lot weaker than a forged stem.
    Transition Patrol - viewtopic.php?f=10017&t=13070235
  • Huckfinn
    Huckfinn Posts: 142
    Is it just me but there doesn't appear to be a weight difference. Any chance we could have a close up of the surface finish as that will determine if it has been CNC cast or other. Then again it could have been forged and then cnc.
  • Huckfinn
    Huckfinn Posts: 142
    http://www.goodluckbuy.com/tmc-mtb-bike ... one-f.html

    more details here seems legit (ish)
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    Thats a die cast finish, definitely not cnc
    The website name says it all, Good luck....
    Transition Patrol - viewtopic.php?f=10017&t=13070235
  • jquach
    jquach Posts: 29
    Huckfinn wrote:
    Is it just me but there doesn't appear to be a weight difference. Any chance we could have a close up of the surface finish as that will determine if it has been CNC cast or other. Then again it could have been forged and then cnc.

    some close up photos.

    TMCSTEM8_zps4a0a00b3.jpg
    TMCSTEM7_zps82adc5ad.jpgTMCSTEM6_zps59d809ee.jpgTMCSTEM5_zpsa8e4d4cf.jpgTMCSTEM4_zpsa1f9c5ce.jpgTMCSTEM3_zps90cf7ba8.jpg
  • The Rookie
    The Rookie Posts: 27,812
    Which, despite earlier posts, is clearly CNC finished.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • supersonic
    supersonic Posts: 82,708
    Definitely cncd. But was it forged first?
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  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    At that price, unlikely.
    I wouldn't want to risk a dodgy stem especially when the genuine Renthal is quite flexy.
    Transition Patrol - viewtopic.php?f=10017&t=13070235
  • The Rookie
    The Rookie Posts: 27,812
    supersonic wrote:
    Definitely cncd. But was it forged first?
    Of course that is impossible to tell, but some shockingly bad posts in this thread from people who I thought knew better!
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • njee20
    njee20 Posts: 9,613
    What makes the OP think it's a copy, out of interest?
  • IDave
    IDave Posts: 223
    Huckfinn wrote:
    http://www.goodluckbuy.com/tmc-mtb-bike-cnc-6061-t6-aluminum-downhill-stem-50mm-2tone-f.html

    more details here seems legit (ish)


    I wouldn't even consider ordering something from a website that looked like that. It looks so dodgy it almost couldn't be a scam site as any half decent scammer would have put more effort into it than that!

    I'd still steer well clear though.
  • jquach
    jquach Posts: 29
    njee20 wrote:
    What makes the OP think it's a copy, out of interest?

    Apart from the design, it's cheap and purchased from a ebay seller from the far east. Also I'm assuming Renthal stuff is made in the UK.
  • The Rookie
    The Rookie Posts: 27,812
    jquach wrote:
    Also I'm assuming Renthal stuff is made in the UK.
    Almost certainly not....
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    The Rookie wrote:
    jquach wrote:
    Also I'm assuming Renthal stuff is made in the UK.
    Almost certainly not....

    Designed in the UK. Made all over the world.
    Transition Patrol - viewtopic.php?f=10017&t=13070235

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