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Why the short seat tubes?

RockmonkeySCRockmonkeySC Posts: 15,247
edited February 2015 in MTB general
Why is it that seat tube lengths have got shorter? Large frames always used to have a 19" - 20" which was fine. Now they seem to have gone down to 17.5" - 18" which is too short for me even with a 400mm seat post.
Why the change? Is there a good reason Im missing?

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  • HerdwickHerdwick Posts: 523
    enduro
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    More clearance for my huge sack.
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  • lawmanlawman Posts: 6,868
    Dropper posts. Specifically 150mm droppers. Personally Im all for it, as a rider with shorter legs and longer body I need a shortish seat tube and a long top tube. Sounds like it's the other way round for you, but that's life and just the way the industry seems to be heading. You win some you lose some

  • RockmonkeySCRockmonkeySC Posts: 15,247
    Im struggling to find any bikes which will fit me now other than xc bikes. A few of my mates are having a similar problem. A 19" frame with a 400mm seat post is on the limit.
    The Mega works for me because the top tube is short for an XL but it has a 20" seat tube which is enough. Ideally I would like to buy a Transition Scout, similar to the Mega but properly built or even a Patrol or a Devinci Spartan but it's looking like Im going to have to go for a custom frame. My legs aren't that long for my height!
  • paul.skibumpaul.skibum Posts: 4,068
    You can get a 430mm reverb with an 80mm minimum insertion, so 350mm out the top. On my medium Bronson I have about 150mm of seat post showing above the frame. I seem to recall you are around 6'2? Even if all 8 inches of height you have on me was leg on you I make that 200mm which would mean you could ride a medium bronson with a long enough seatpost......

    Am I missing something with my maths?

    Personally I'd like a shorter seatpost on my bike so I could get a longer dropper on it over the 100mm I have.
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  • RockmonkeySCRockmonkeySC Posts: 15,247
    Longer Reverbs are less reliable. I have been advised by someone who works with them never to buy one. The bushes wear much quicker than the shorter Reverb because of the flex when extended. Aparently ither brands are similar.
    I could actually go for an XL Bronson, the sizing is ok but I just dont like them.
  • The RookieThe Rookie Posts: 27,748
    lawman wrote:
    Dropper posts. Specifically 150mm droppers. Personally Im all for it, as a rider with shorter legs and longer body I need a shortish seat tube and a long top tube. Sounds like it's the other way round for you, but that's life and just the way the industry seems to be heading. You win some you lose some
    But a shorter leg also means a shorter arm and that means you would want a shorter top tube, your arms account for much more of the reach from saddle to grips than your torso...as someone with shorter legs I find I usually go down a frame size.
  • Similar issue going Medium on the Nomad and showing a lot of post. Long legs and short arms doesn't help matters. More upright seating position could be to blame as the height relative to the floor will increase as you go more upright although this doesn't account for an inch difference in some frames. Other reason could be for manufacturers trying to achieve a more in the bike feeling by moving rider CofG further forwards and forcing upsize.
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