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Minimum seatpost length?

Discussion in 'Bicycle Mechanics and Repairs' started by twowheelsgood, 2 Aug 2007.

  1. twowheelsgood

    twowheelsgood Senior Member

    Location:
    Zurich Switzerland
    Hi, I have a bog-standard alloy seatpost but it really is preposerously long, having around 30cm inside the frame.

    How short could I cut it and still remain safe i.e. mainly not damaging the frame or risk having the post snap?
     
  2. chris42

    chris42 New Member

    Location:
    Deal, Kent
    measure from the min insert line to the end then that is the safe amount you need to leave
     
  3. OP
    OP
    twowheelsgood

    twowheelsgood Senior Member

    Location:
    Zurich Switzerland
    It is not marked with a minimum insert line.
     
  4. Steve Austin

    Steve Austin The Marmalade Kid

    Location:
    Mlehworld
    At least an inch below the bottom of the intersection of the toptube and seattube is the most often head advice. If its a compact frame with a low toptube it can mean a lot of seat post still.
     
  5. MichaelM

    MichaelM Veteran

    Location:
    Tayside
    Without going and measuring, I reckon the min insert of a Thomson post on the mtb is around 11/12 cm - thats on a 44cm post. I'd say you could quite safely cut it to have an insert of 15cm (probably a bit less).
     
  6. OP
    OP
    twowheelsgood

    twowheelsgood Senior Member

    Location:
    Zurich Switzerland
    Thanks all,

    I'll leave 5cm/2ins in the frame. It's actually for my hybrid. What on earth made me buy a 40cm post in the first place!!
     
  7. Steve Austin

    Steve Austin The Marmalade Kid

    Location:
    Mlehworld
    you'll want more than 5cm ;)
     
  8. TimO

    TimO Veteran

    Location:
    London
    Why do you want to cut it off? Is it difficult to get in, or are you just trying to save a bit more weight?
     
  9. barq

    barq Senior Member

    Location:
    Birmingham, UK
    *looks up*

    What he said.
     
  10. Monty Dog

    Monty Dog New Member

    Location:
    Fleet
    Minimum of 3x diameter - so 100mm to be absolutely on the safe side
     
  11. OP
    OP
    twowheelsgood

    twowheelsgood Senior Member

    Location:
    Zurich Switzerland
    Hi OK 10cm it is. I want to cut it because it takes a ridiculous amount of time to get in and out of a frame and it's tricky looking after a 40cm greasy pole (oo-er) when you remove it for security. As it has my Brooks attached to it, weight isn't exactly the issue!
     
  12. punkypossum

    punkypossum Donut Devil

    I always thought you had to leave at least a third of the total length inside the frame?