Why are seatposts so long?

aggrodan
aggrodan Posts: 8
edited March 2015 in MTB general
I'm used to riding with my seatpost as low as possible as I attack downhill trails. It's good to keep it out the way and keep my centre of gravity low. I'm looking to buy a new seatpost for my Orange Crush and I'm struggling to find any that are shorter than 350mm in length. A seatpost this length would not let me drop the seatpost far enough to comfortably ride downhill as I'm used to. Why are seatposts for mountain bikes so long now? Can anybody advice me where to pick up a mtb seatpost that is 280-300mm in length and 27.2mm or 30.9mm in diameter (I have a 27.2mm shim if need be). If all fails I guess I would have to just cut down a seatpost to length. Is this advisable? Thanks in advance for any suggestions and help. :D

Comments

  • Chunkers1980
    Chunkers1980 Posts: 8,035
    Some carbon shouldn't be cut. But with aluminium all you lose is the minimum insertion line being relevant.
  • cooldad
    cooldad Posts: 32,599
    Just cut it down, but there is a minimum insertion length. Too short and your frame will break, and you may die.
    I don't do smileys.

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  • njee20
    njee20 Posts: 9,613
    Chunkers1980 wrote:
    Some carbon shouldn't be cut. But with aluminium all you lose is the minimum insertion line being relevant.

    Very very few to be fair, some ultra lightweight ones have a 'clamping zone', but they're firmly in the minority. Most carbon can be cut happily.

    To answer your question OP it's because they're designed to be the long enough to get your saddle into the right place to pedal. They're not long "now", they've always been long!
  • The Rookie
    The Rookie Posts: 27,812
    On an MTB the preference has slowly shifted to getting the top tube lower for clearance (when riding, not just for standover), also you want the saddle out the way at times, that means a long seatpost to put the saddle in the right place for pedalling.

    The carbon ones with a clamping zone can't be ridden dropped anyway so doubt that will effect you, also on many frames (especially carbon) the section of the seat tube that is a snug fit to the post is only the top 4" or so anyway.

    If it's too long, just shorten it.
    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.
  • lancew
    lancew Posts: 680
    a) Because you can shorten them.

    b) Because tall people who ride XC/Roadbikes exist and need to be in a higher more efficient position for pedaling.

    If you're going to cut it down, maybe get a second hand post on the forum?
    Specialized Allez Sport 2013
  • Angus Young
    Angus Young Posts: 3,063
    Just for fun and confusion this thread should be merged with this thread...

    viewtopic.php?f=10002&t=13017120
    All the gear, no idea and loving the smell of jealousy in the morning.
    Kona Process 134 viewtopic.php?f=10017&t=12994607
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    Get out the hacksaw. If a 350mm post cant be dropped low enough on a hardtail then either your frame is too big or you have a really weird riding style. Just look at how high downhill racers run their saddles. Enduro racers aren't much slower down a hill and only drop their saddles around 5" from pedalling height.
    Personally Im struggling to find a frame with a long enough seat tube to allow me to get my saddle high enough with a 400mm post.
    Transition Patrol - viewtopic.php?f=10017&t=13070235
  • aggrodan
    aggrodan Posts: 8
    Thanks for all the responses. It appears my previous seatpost must have been an anomaly then. I have been carrying around the same seatpost for 8 years now moving it from bike to bike. Perhaps as you say Rockmonkey my riding position is a bit odd. I just like getting the saddle as far out the way as possible. I've come across a 300mm seatpost which would be perfect for me , it's an Easton EA70 Zero seatpost. Gonna try that. If all else fails I'll buy the seatpost I want and cut it to my preferable size.
  • The Rookie
    The Rookie Posts: 27,812
    What diameter?
    I have a good quality ITM seatpost in 27.2mm flavour that's already been shortened that's soon to be removed!
    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.
  • paul.skibum
    paul.skibum Posts: 4,068
    Buy a dropper post - comes in 30.9 and allows you to drop the saddle out the way when you want but have a good seated pedal when you need it. Sure its a few notes more but if you have had one post for 8 years it seems like you could treat yourself!
    Closet jockey wheel pimp whore.
  • Angus Young
    Angus Young Posts: 3,063
    paul.skibum wrote:
    Buy a dropper post...

    Best thing since sliced bread.
    All the gear, no idea and loving the smell of jealousy in the morning.
    Kona Process 134 viewtopic.php?f=10017&t=12994607
  • robertpb
    robertpb Posts: 1,866
    Having a look at my old 1987 rigid today I thought that seatpost has to be longer than 350mm, it was, 440mm I had it made by Dave Wrath-Sharman as a 350 Suntour was too short.

    You may think I must be a giant but no 5'5".
    Now where's that "Get Out of Crash Free Card"
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    Angus Young wrote:
    paul.skibum wrote:
    Buy a dropper post...

    Best thing since sliced bread.

    Sliced bread was more reliable.
    They're good but I could live without my reverb. I don't see it as essential like some people do.
    Transition Patrol - viewtopic.php?f=10017&t=13070235

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