Seat angle

akcc05
akcc05 Posts: 336
edited January 2009 in MTB general
Coming from a road backgroud, I've come to realize that seat angles vary from bikes to bikes in MTBs much more than that in road bikes. In my understanding, the ideal seating position is such that your knee joint is vertically in line with the pedal axles when the cranks are flat and parallel to the groud. My newly aquired full sus frame has a seat angle of 72.2 which is really low and I have long legs (more seatpost extension = even slacker angle). So, my question is: how is it possible to get the right seating position with such a slack seat angle, especially when my thighs are short and my lower legs takes up most of my leg length?

The reason why I'm asking is because I'm looking for a seatpost with the right setback to complete my build.

Thank you all and have a lovely evening!

Comments

  • nicklouse
    nicklouse Posts: 50,673
    Mmmm the thing with riding an MTB is that you are very rarly seated in the same position if you are seated at all.

    Soo it does not matter that much.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Banned!
    Banned! Posts: 34
    I only really use my seat for steering and stopping the frame hitting me in the nuts.
  • akcc05
    akcc05 Posts: 336
    In that case my off road riding needs to be improved as I'm seated most of the time, I have only recently started riding off road though.

    From a little experiment I did on my road bike, I found that power transfer and efficiency falls quite dramatically when I move my saddle backwards and sit as far back as possible...hence my worry.
  • akcc05
    akcc05 Posts: 336
    Jesus_Christ wrote:
    I only really use my seat for steering and stopping the frame hitting me in the nuts.

    Wouldn't you feel tired if you do all day rides? Long rides and marathons are what I'm building my full sus for.
  • Banned!
    Banned! Posts: 34
    i dont ride all day though. i spent maybe 5-6 hours on the bike maximum. ok, I do sit down, but i dont expect to get maximum power transfer from that position.

    mtbs are totally different from roadies. somebody who knows more about pedalling dynamics and power transfers should explain this, but an mtb isnt built for all day riding (apart from some xc bikes) but are for thrashing about for relatively short distances.
  • akcc05
    akcc05 Posts: 336
    Ah, I see. Thanks for the help guys. And, if it is not too much of a hassle, could you guys tell me if your knees are vertically above the pedal axles when the cranks are flat (might do a poll later)? I'm thinking of getting a Thomson seatpost but I'm not sure if I should get the set-back or straight ones. Thanks.
  • supersonic
    supersonic Posts: 82,708
    Some are for relatively short distances. Many aren't! Your bike is totally different from my Zaskars, and a lot are made for long XC/Marathon/Enduro type rides.

    I ride a lot of XC, and like a fairly steep seat angle as I find it does offer optimal pedaling efficiency. 72 is not that slack on an MTB, and by sliding the saddle on its rails you might be able to find a good compromise - hopefully without shortening the reach.
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  • Soggz
    Soggz Posts: 221
    My seats right back on the rails on a horizontal angle, but i dont sit on it much! on the (reletive) flat, i grip it with my thighs and use it to 'power pedal'...Only really use it on the road inbetween trails..

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