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26.8mm seatpost in a 26.6mm frame

Discussion in 'The Shop' started by the_prozac_kid, Oct 22, 2003.

  1. the_prozac_kid

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    i was just wondering if anyone can give some advice about fitting a 26.8mm seatpost in a frame designed for a 26.6mm seatpost?

    the bike i have is a 2000 norco nitro and norco in their infinite wisdom decided that a 26.6mm seatpost would fit nicely. however except for axiom (norco's component arm) and a couple of companies no one makes 26.6mm seatposts! not even easton!

    i have my eyes on a cane creek thudbuster and the smallest diameter is 26.8mm, is this going to work or will i be tempting fate!

    any help would be great!!:confused:
     

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  2. binary visions

    binary visions The voice of reason

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    Would recommend against it. A) it probably won't fit, and B) you run a much higher likelihood of the thing seizing up and you never being able to remove or move your seatpost again.

    If you DO try it, just use copius amounts of grease. You might be able to dremel a little material out of the top of your seatpost to make it fit. Just depends on how comfortable you feel with removing frame material.
     
  3. Repack

    Repack Turbo Monkey

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    I would try to flex-hone (sp?) it out. A fexhone is like an industrial pipe cleaner that fits into a drill. Shops use them to clean out seat tubes on bikes. Fairly often they come from the factory with crap in them and need to be cleand out. I can't see how the removeal of .1mm of wall thickness could hurt anything. If you want to buy one they have em at Sears. They do come in different sizes so if you buy one, get the one that fits the closest. Buying one may be cheaper than paying a shop to do it. I'd bet that most hardware stores also stock them.
     
  4. speedbump

    speedbump Chimp

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    A flexhone will take forever. Do it the right way and find a shop with a seat tube reamer. It will shave off exactly the right amount of material from the inside of your seat tube and voila, your bike will then have a 26.8mm seat tube.:)
     
  5. Repack

    Repack Turbo Monkey

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    A new flexhone wouldn't take too long to knock down .1mm, and would be much cheaper than paying a shop to use the reems. Shops in general aren't cheap when it comes to doing work with expensive cutting tools that require a degree of skill to use. A brand new flexhone with no oil should not take long at all, especially if the drill is fast.:D
     
  6. sub6

    sub6 Monkey

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    nah, should be lickity-split. Unless it's a steel bike, that would take considerably longer.
     
  7. gorgechris

    gorgechris Monkey

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    Damn, I learn something new each day on this site.

    Of course, power tools in the wrong hands can be very dangerous to one's wallet.
     
  8. the_prozac_kid

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    the frame is 7005 aluminium alloy. i'm pretty sure i know what you mean by a flex hone (its used on engine blocks). i wondering if it will just fit albeit a tight one, given that the difference in diameters is less than 1% of the overall seatpost diameter. i don't know how strict tolerances are in bike frames.

    thanks:)
     
  9. PsychO!1

    PsychO!1 Monkey

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    I'm not familiar with the nitro....but, If this is for DJ/Urban type stuff and seat is gonna be low and not really used alot, I'd say try the honing. But if it's an XC bike, your a$$ is gonna be pounding that post hour upon hour. I would think twice about removing material from the seat tube. I know the AL tubing can be pretty thin walled these days, be carefull.
     
  10. RhinofromWA

    RhinofromWA Brevity R Us

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    Personally I think he just needs a bigger hammer..........



    It'll fit....come on hit it like a man! :D
     
  11. Joe33

    Joe33 Guest

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    You should measure the inside and see exactly what size it is. For a good fit it should be about .07-08mm or so oversize. If its to small and your really content on putting a specific seatpost in there your best bet would be to call up a machine shop and ask them to take off the material. They have adjustable reamers that can do it much faster and more precise than you armed with a drill hone and it shouldn't cost much either. If you do decide to use a hone make sure to get one that uses sand paper or something that will work on aluminum. Some of them use stones which the aluminum would just gauld up on.

    Forgot, make sure and measure the post to 26.8 is usually not quite 26.8
     
  12. Motionboy2

    Motionboy2 Calendar Dominator

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    Why don't you just get a Thomson? They make a 26.6 and Quality has plenty in stock so your local dealer could have it for you ASAP!

    Or if you NEED to have a suspension seatpost get a USE or RockShox and a seatpost shim for 26.6
     
  13. PsychO!1

    PsychO!1 Monkey

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    That's the best solution yet!!! Just get the right part for your bike.
     
  14. the_prozac_kid

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    i know that suspension seat posts can be a bit of a gimmick, but i thinking of using one in endurance races eg/ 24hr races to reduce fatigue.

    how do the USE, RockShox compare to the cane creek thudbuster?
     
  15. speedbump

    speedbump Chimp

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    I've never used a Thudbuster or USE post, but I did race with a Rock Shox post for an entire season and thought it worked great. It held up fine (I'm 210+lbs.) and I was never bothered by the "changing" seat height sensation that some people mention. I set it up just the way they described with about 3/8" of sag.
     
  16. Motionboy2

    Motionboy2 Calendar Dominator

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    Sorry for the delay, I forgot to check this thread.

    The RS and USE are a straight path and the thudbuster is a paralelogram. The Thudbuster moves you back a bit behind your pedals. No matter what they will constantly change your saddle height.
    My opinion is that if you are getting a suspension seatpost I would get one with a minimal travel to just take the edge off. If you get a long travel one then your saddle height will change by up to 3 inches! That is not very efficient.
     
  17. switch

    switch Chimp

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    I had the same problem with an older Noro Bush Pilot frame I picked up. I've got a spare 26.8mm post, but it was a tad too big. A local sports swap store had a brand new 26.4mm post for $15, and it works. So I'd suggest first looking at used bike shops.

    Another option. Some bike shops have seat tube reamers, whose purpose I believe is to remove irregularities from the inside of the tube. A friend of mine wanted a 0.2mm larger seat post than his tube allowed, and he was able to use the reamer to take off enough so that the larger post would fit (snuggly).