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Seat post length + introducing myself!

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  • Seat post length + introducing myself!

    Hi all,

    I have been trying to learn how to unicycle in earnest for the last couple of months, after dipping my toe in the water briefly last year before the winter set in. I am at the stage where I can wobble for a hundred foot or more on most attempts, and as my legs have started killing me, and in an effort to make me sit down more, I have been raising the saddle a lot recently.

    When I first got my 24" Club Muni I cut the seat post down a bit, not realising that as I gained in confidence I would be increasing the height of the saddle so much!

    My question is, how much seat post do you think you need in the frame before it becomes unsafe? I think it is okay at the moment, but I just seem to keep on raising it!

    Thanks
    You can only do what you can do, you can't do what you can't do.

  • #2
    I just checked my 24' Muni, the same model as yours, I fitted a longer seat post last year, but at the moment, after cutting it down a mite last year, I have about 4" inside the frame tube. I suspect roughly 3" is the minimum required, but others may well be more expert......
    I am not really old, I just highlight my hair to look more extinguished..

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    • #3
      Originally posted by Barnstar View Post
      I am at the stage where I can wobble for a hundred foot or more on most attempts
      Congratulations! You are a unicyclist.

      my legs have started killing me, and in an effort to make me sit down more, I have been raising the saddle a lot recently.
      Been there, created a thread on that:

      http://unicyclist.com/forums/showthread.php?t=118140

      It does get better - seat height is important, but a lot of it is just practice learning to give the wheel only what it needs, with no wasted leg effort. Soon the only leg stress is pushing up hills, retarding down them, and occasionally partly standing for a few revolutions to relieve saddle pressure.

      Club seatposts are cheap, problem is shipping will double the cost. Next time you have cause to order something it's worth getting a spare. Also keep an eye on craiglist or other local classified for additional unicycles - you can never have too many :-)
      Nimbus 36 & 26

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      • #4
        If manufacturers "minimum insertion" lines are to be believed you should have 100mm/4" of post in the frame, but I think you are safe with about half that, as long as it goes deeper than the slot cut for the seatpost clamp.
        Last edited by saskatchewanian; 2017-05-12, 06:56 PM.
        My friends, love is better than anger. Hope is better than fear. Optimism is better than despair. So let us be loving, hopeful and optimistic. And we’ll change the world. - Jack Layton

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        • #5
          As a bare minimum, I'd say about 50mm (2", which is about double the height of a typical seat clamp), but for any kind of long term use I'd want to go double that, if possible. It's less of a big deal if you don't think you will ever fall on the unicycle, or subject it to similar side-force impacts that might damage (or break) your seat tube.

          Yes, when learning, having the seat as high as possible will help your legs to not overdo it. The basic rule for this is that if you're sitting on the seat with one pedal at the bottom, and your foot centered on that pedal, you should still have a little bit of bend in your knee but not much. Then ride with the balls of your feet on the pedals to get the maximum benefit of your ankle power.
          Last edited by johnfoss; 2017-05-12, 07:12 PM.
          John Foss
          www.unicycling.com

          "Who is going to argue with a mom who can ride a unicycle?" -- Forums member "HiMo"

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          • #6
            Thank you for all the replies. I think buying a spare post farther down the road is a good idea. Although I am trying very hard not to buy more unicycles before I have mastered this one! : )

            Regina, I have been following your progress, along with the progress of SpinningWoman and others, with great interest! I think you are both a bit further along than me as I have not even attempted free mounting yet! I am trying to nail down my balance to hopefully make learning to freemount a lot easier, as it seems impossible to me at the moment! Also, I don't think you live that far from me (for two random people on the internet that is : ) Ipswich being about the halfway point between us! Devon on the other hand is quite some distance away! At least it is by UK standards anyway, we are not quite as spread out as some of the places in the US!
            You can only do what you can do, you can't do what you can't do.

            Comment


            • #7
              Thanks for your replies, I tried saying thanks yesterday but the post never appeared.

              Does every post have to be checked by a moderator, or is it just because I am new here?
              You can only do what you can do, you can't do what you can't do.

              Comment


              • #8
                Originally posted by Barnstar View Post
                Thanks for your replies, I tried saying thanks yesterday but the post never appeared.

                Does every post have to be checked by a moderator, or is it just because I am new here?
                Neither. You probably clicked the wrong button.
                I have the Midas touch.
                Everything I touch turns into a muffler.

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                • #9
                  Nevermind, it must have been because I was new as the above post appeared instantly!

                  I went out again today to practice, but could only manage half an hour and it was clear that my body was not as willing as my mind! I am going to have to leave at least a day or two gap in between sessions or my body just can't handle it. I have found it quite surprising as I cycles thousands of miles a year commuting to work. I know I know, it just takes time!
                  You can only do what you can do, you can't do what you can't do.

                  Comment


                  • #10
                    Originally posted by johnfoss View Post
                    As a bare minimum, I'd say about 50mm (2", which is about double the height of a typical seat clamp), but for any kind of long term use I'd want to go double that, if possible. It's less of a big deal if you don't think you will ever fall on the unicycle, or subject it to similar side-force impacts that might damage (or break) your seat tube.
                    The longer the insertion of a seat post into the seat tube the further down the seat tube the load is applied. However this is surely only where the post fits fairly precisely inside the tube?

                    Many seat tubes are flared immediately below the clamp to increasing their diameter. As such, insertion beyond the flare, per se, is surely irrelevant? The determining factor for minimum insertion would seem the length of post below the clamp such that the pressure of the clamp does not significantly deform the post due to the proximity of its end.

                    Perhaps Engineer could calculate how far that would be, or suggest other mechanical constraints? My initial guess would be a diameter of the seat post past the bottom of the clamp.
                    Last edited by OneTrackMind; 2017-05-13, 01:27 PM.
                    Triton 36" + 29" | KH 29" | KH 26" | KH 27.5" Muni | Nimbus eSport Race 24" | Torker LX 24" | Qu-Ax Luxus 20" | Qu-Ax Profi 20" | KH / Impact 19" hybrid

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                    • #11
                      Sorry, not my field of engineering. My gut feeling is you'd have to consider the flex in the materials as well as the geometry, but I'll leave analyzing it to someone who took the course where you were handed a piece of uncooked linguini and tasked with determining its utility as a bridge girder... without breaking it.

                      I did finally bring myself to cut off the part of the seatpost on my 36er that would be out of contact within the flared part of the seat tube anyway, in order to experiment with slightly lower seat positions (ended up dropping it about a centimeter from where I started) and accessories mounting through the hole there.
                      Nimbus 36 & 26

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