• 09-04-2010
    Gman086
    Anyone ream out the seat tube to 30.9 for adjustable posts?
    As title states... my 6 Point is in desperate need of a KS 900!

    Have FUN!

    G MAN
  • 09-07-2010
    UncleFeet
    Oh man!...My MKIII comp needs a Joplin 4...but I just couldn't bring myself to ream the .45mm out of the seat tube, it's wall being only about 2mm itself...I was looking for a KSi950 too but no Aussie distributor...and my mate and I got a good deal on 2 Jop 4's...but I took mine back to the shop....

    But, would it be dangerous,?...the inherent strength of the tube shape should hold up...and wouldn't a stiff post in the tube add strength?...I don't really know...so I chickened out...

    I'll be watching this thread with interest

    Good luck mate...
  • 09-07-2010
    Uncle Jemima
    I don't see how doing this, even with local Hardware Store material, would be bad considering the amount of material needing removal. 1/4 or 5/16" non threaded stock @ 2ft, lengths of Belt-Sander sandpaper in 100-400 Grit, and cutting a gap in the end this rod. Tighten a wrap of the cut sanding belt, and run a low-speed drill with the Coarse, finish-sand with 400 grit or higher depending. Should be a non-issue. I'm keeping my rigid seatpost though.
  • 09-07-2010
    KiwiJohn
    Not like it'll void your warranty.
  • 09-08-2010
    saturnine
    go ahead. it won't crack at the seat tube anyway.
  • 09-13-2010
    ride_nw
    Quote:

    Originally Posted by Gman086
    As title states... my 6 Point is in desperate need of a KS 900!

    Have FUN!

    G MAN

    I have to admit when I first read this I didn't think it was a good idea but I now I get it. Look at all of the other bikes with a 30.9... they all run a 34.9 clamp, same as the 6 point. Thinking back, I actually had a bike with a 31.6 seatpost which meant the walls were even thinner. I am totally down for this mod, but what is the best way to do it?
  • 09-13-2010
    UncleFeet
    ...personally, if I was to have it done, I'd take the frame to an engineering workshop and have it done precisely...preferably by a German engineer of advanced age...
  • 09-14-2010
    Uncle Jemima
    You realize only the first 3-4 Inches of the SeatTube are 30.9mm, right?
  • 09-14-2010
    saturnine
    Quote:

    Originally Posted by Uncle Jemima
    You realize only the first 3-4 Inches of the SeatTube are 30.9mm, right?

    what?
  • 09-14-2010
    Uncle Jemima
    What what? If the length was entirely 30.0 to the BB Juncture, the seat post would slip when clamped. It would be flare right at the Clamp. The Seat-Tube sees a very slight taper, and tooling it .45mm a side larger is not going to create anything in slippage issues; a 31.6mm FSA post though? Never. Return the metal to nearly as smooth as it is, if not smoother. I'd say if could be done, but I have no want or need for a bouncy seatpost.
    You are going to keep this post rigidly in-place anyway, because it is self-adjusting. A bolt-style clamp will afford better retension then a QR-style.

    Quote:

    Originally Posted by saturnine
    what?

  • 09-14-2010
    ride_nw
    Quote:

    Originally Posted by Uncle Jemima
    What what? If the length was entirely 30.0 to the BB Juncture, the seat post would slip when clamped. It would be flare right at the Clamp. The Seat-Tube sees a very slight taper, and tooling it .45mm a side larger is not going to create anything in slippage issues; a 31.6mm FSA post though? Never. Return the metal to nearly as smooth as it is, if not smoother. I'd say if could be done, but I have no want or need for a bouncy seatpost.
    You are going to keep this post rigidly in-place anyway, because it is self-adjusting. A bolt-style clamp will afford better retension then a QR-style.

    I've read your post a couple of times and I still have no idea what you are talking about.
  • 09-15-2010
    Uncle Jemima
    There is a response above that prompted it. Very slightly the I.D. of a Seat Tube will grow as it reaches the Bottom-Bracket juncture. The design affords it. How long is one of these that only will rest in the Seat-Tube anyway? No more than 5-6 inches, and that is where most the compression-fit is natural. I thought at nite, and perhaps some Mountain Bikes would have absolutely straight tubing. People shim posts all day, and they hold. I am not saying this cannot fail, but taking it from 30.0 to 30.9mm is not a ridiculous idea. If if bothers still, put a dowel end in one end of the post, and run a belt-sander on that.
  • 09-17-2010
    namastebuzz
    Why not get a Gravity Dropper and a shim?
  • 09-17-2010
    Gman086
    Because my 6 Point needs and offset post - no ifs ands or buts about it!
  • 09-17-2010
    wormvine
    Quote:

    Originally Posted by Gman086
    Because my 6 Point needs and offset post - no ifs ands or buts about it!

    Here you go GMAN. When you are done using it... send it to me!

    http://www.chadwickreamers.com/angle...ure=fractional
    You need size 29.

    Here are some instructions...
    http://mountainbikers.hubsystems.com...s/chapter7.pdf
  • 09-18-2010
    Gman086
    Quote:

    Originally Posted by wormvine
    Here you go GMAN. When you are done using it... send it to me!

    http://www.chadwickreamers.com/angle...ure=fractional
    You need size 29.

    Here are some instructions...
    http://mountainbikers.hubsystems.com...s/chapter7.pdf

    AWESOME! :thumbsup:
  • 09-18-2010
    namastebuzz
    Quote:

    Because my 6 Point needs and offset post - no ifs ands or buts about it!
    Fair point.


    Looked at those instructions and noticed it said it wasn't designed to allow a larger size post to fit and if used to do so "the job would take an unbelieveably long time to complete".
  • 09-18-2010
    extremecarver
    I know people have successfully shaved 30.9 Kindshock I900 to 30mm diameter. Only the bottom 2cm are delicate. I'ld probably think best grind down on both and settle with 30.5mm..
  • 09-20-2010
    Uncle Jemima
    This is going to be the best-bet. I actually went and 'wiggle' tested my bikes, and there is different give within the Seat Tube on each.
    If this Seatpost does come apart, it should, get an aluminum rod from Hardware Store and find a Wood Working Shop with a stationary belt sander. Throw some belts at them and ask for them to knock it down by spinning it on the Rod. If you have the ST be symetrical with the post, it will crack. Smoothing the post to a thinner Diameter sounds fine.

    Quote:

    Originally Posted by extremecarver
    I know people have successfully shaved 30.9 Kindshock I900 to 30mm diameter. Only the bottom 2cm are delicate. I'ld probably think best grind down on both and settle with 30.5mm..

  • 09-28-2010
    ride_nw
    Quote:

    Originally Posted by wormvine
    Here you go GMAN. When you are done using it... send it to me!

    http://www.chadwickreamers.com/angle...ure=fractional
    You need size 29.

    Here are some instructions...
    http://mountainbikers.hubsystems.com...s/chapter7.pdf


    My LBS has one... I am tempted.

    What about the stress riser as someone mentioned? Any engineers in the house? I do not doubt that this process will result in a weaker seat tube, but realistically how big of a deal is it?
  • 09-28-2010
    wormvine
    Quote:

    Originally Posted by ride_nw
    My LBS has one... I am tempted.

    What about the stress riser as someone mentioned? Any engineers in the house? I do not doubt that this process will result in a weaker seat tube, but realistically how big of a deal is it?


    Regarding the "stress rider" mentioned in the pdf.
    I doubt it would affect it at all in respect to the 6point. The rocker links mount to a bracket that surrounds the tube. This adds strength to the tube. The short support tube that connects the top tube to the seat tube also adds a decent amount of support. Remember the 6point's seat tube is thicker than the standard 30.9 seat tube.
    In comparison, The 09' Reign my wife has uses a hydroformed bulge that has a sleeve piercing it for the rocker bolt. That is why there is a limited insertion depth of the seat tube. A common complain of Giant Reigns. There is also a little lip of aluminum inside the tube left over from the final reaming of the hydroformed tube. If giant isn't worried about this lip, I wouldn't worry about it.

    I will probably try this in the Spring before the season opens up for me. I will post up the results if/when it happens.
  • 09-28-2010
    ride_nw
    Quote:

    Originally Posted by wormvine
    Regarding the "stress rider" mentioned in the pdf.
    I doubt it would affect it at all in respect to the 6point. The rocker links mount to a bracket that surrounds the tube. This adds strength to the tube. The short support tube that connects the top tube to the seat tube also adds a decent amount of support. Remember the 6point's seat tube is thicker than the standard 30.9 seat tube.
    In comparison, The 09' Reign my wife has uses a hydroformed bulge that has a sleeve piercing it for the rocker bolt. That is why there is a limited insertion depth of the seat tube. A common complain of Giant Reigns. There is also a little lip of aluminum inside the tube left over from the final reaming of the hydroformed tube. If giant isn't worried about this lip, I wouldn't worry about it.

    I will probably try this in the Spring before the season opens up for me. I will post up the results if/when it happens.

    Cool, thanks for the reply. My gut instinct says it shouldn't be a problem. I am not in a big hurry, I will probably do it sometime over the winter as well.
  • 09-29-2010
    qbert2000
    my banshee rune has a 30mm seat tube as well. i pm'd keith the banshee engineer and he said the new seat tubes are 30.9 id but the same od so making mine 30.9 would not weaken it beyond what it is designed to do. the problem was that the frames are heat treated and hard enough that they will chip when reaming not cut smoothly. he said it could be done with care but he wasn't promising success. i have been waiting to see the shop guy from one of the machine shops we deal with at work to ask him about it. want to do the reaming but i am a little leery
  • 09-29-2010
    Gman086
    Good info everyone! Now who's gonna go first?!

    Cheers,

    G
  • 09-29-2010
    marshallmthomas
    Not it!
  • 09-29-2010
    ride_nw
    Quote:

    Originally Posted by qbert2000
    my banshee rune has a 30mm seat tube as well. i pm'd keith the banshee engineer and he said the new seat tubes are 30.9 id but the same od so making mine 30.9 would not weaken it beyond what it is designed to do. the problem was that the frames are heat treated and hard enough that they will chip when reaming not cut smoothly. he said it could be done with care but he wasn't promising success. i have been waiting to see the shop guy from one of the machine shops we deal with at work to ask him about it. want to do the reaming but i am a little leery

    Interesting. I do not know how sharp the tool is at the shop... maybe it is thrashed and will not cut smoothly. Anyways thanks for the info, very much appreciated. If I talk myself into doing it I will let you guys know, but I'm not in a hurry.
  • 10-01-2010
    marshallmthomas
    Correction: Rick was referring to the I-7 which is only a 100mm travel post. The I-7 will be available in 27.2 in 3 weeks if you can cope with 100mm travel. The I-7 has no set back. Dang.

    Just heard from Rick Taylor at KS. He says a 27.2 version will be available in 3 weeks. If that's the case it'd be easiest to go with the 27.2mm KS900 and then shim to 30mm.

    He said they'll will be available thru wholesalers BTI, QBP and KHS.
  • 11-07-2010
    92SE-R
    Anyone get their seatpost reamed yet?
  • 11-15-2010
    adumesny
    What would you do that and weaken (at best) or ruin your frame ? it's not like you have replacement parts readily available either... Get a gravity dropper (what I have - 4" 27.2mm) and have it fit all all your bikes with just a simple shim..
  • 11-15-2010
    adumesny
    What would you do that and weaken (at best) or ruin your frame ? it's not like you have replacement parts readily available either... Get a gravity dropper (what I have - 4" 27.2mm) and have it fit all all your bikes with just a simple shim.. they are more reliable than anything out there anyway and super simple to take apart to lube once a year (just did mine).
  • 01-25-2011
    skkele
    Just bought a Joplin today and have to make it fit a 2005 Bullit... 28.6mm --> 30.9mm, 2.3mm... .0905"... ouch. Have an adjustable reamer that goes from 1.125" to 1.250" so that should do it but I anticipate lots of passes... like 20. :-/
  • 01-28-2011
    Speedub.Nate
    I know this is hella late to the conversation, but I was contemplating this with my MkIII. I called a local old school frame builder (Bernie Mikkelsen) who seemed agreeable and brought the frame down to him, but when I got there and he figured out what I was really asking him to do he changed his tune.

    Even though it was minimal material to be removed, he felt this sort of cutting would add all sorts of stress risers, explaining that the tubing is extruded at whatever diameter it comes out at and it should be left at that, with just minor reaming if necessary.

    I can't vouch for the guy one way or the other. He works in steel, and I don't think he's a trained materials engineer, but he's been around bike frames for decades so I doubt he was talking out of his azz or shining me on.
  • 01-29-2011
    Uncle Jemima
    I had began riding with a strong BMX background, and worked in a Shoppe when lay-back seatposts were very new. Some racers would have a frame reamed to fit a particular post, but it was very time-consuming. I actually have no idea where all this gadgetry came from; I think it is getting annoying. I mean, I just had FOX SHOX tune my basic DHXAir3--the 6POINT I have with an RS Totem is screaming!!! Pretty soon what is passing for a reliable suspension design is going to find itself out-phased and forgotten about if this gizmo heap-o-la doesn't chill out. Really, it's a bike and it is going to have to be pedaled anywehre it goes. Enjoy it. As far as reaming out an Aluminum MTB Frame, I'd say be safe and just don't do it. Whittle-down that post if at all, there is alot of need placed on these frames other than pedaling & turning.
  • 03-14-2011
    DirtyMartini
    Has anyone tried this yet? It sounds like there's lots of consensus (on other forums also) that a 34.9 OD seat tube is very commonly used with a 30.9 ID and sometimes a 31.6ID.

    On BikeRadar, one a few guys had a very good suggestion. Instead of using a reamer (which is "aggressive" on the metal, and expensive) they said to use an automotive brake caliper honer, which is three grit blocks on a spring loaded tripod. (Google "brake honer" and you see what I"m talking about). You put the thing in a drill and essentially sand off the seat tube material. They they've done it successfully on a few bikes (including a Santa Cruz Bullit). They also said to use WD40 to keep it wet and cool.

    The way heat treating works is that you heat up the metal to a certain temperature and then cool it rapidly. This makes the metal harder & stronger (but also more brittle). If you want to UN-heat treat metal (called annealing) then raise the temperature up to it's heat treat temp (~400F for Aluminum) and then let it cool slowly.

    So I think the key to enlarging the seat tube is to "sand" out the material with a honer (cheap at autozone), keep it moving up and down inside the tube (the springs will keep even pressure against the metal), and keep it lubed with wd40 or cutting oil. The key is to not heat up the metal too much and thus undo the heat treat. Take your time, keep it cool, and keep it honer moving up and down to get a nice even shave.

    What do you guys think?
  • 03-21-2011
    KevinB
    Quote:

    Originally Posted by DirtyMartini
    Has anyone tried this yet? It sounds like there's lots of consensus (on other forums also) that a 34.9 OD seat tube is very commonly used with a 30.9 ID and sometimes a 31.6ID.

    On BikeRadar, one a few guys had a very good suggestion. Instead of using a reamer (which is "aggressive" on the metal, and expensive) they said to use an automotive brake caliper honer, which is three grit blocks on a spring loaded tripod. (Google "brake honer" and you see what I"m talking about). You put the thing in a drill and essentially sand off the seat tube material. They they've done it successfully on a few bikes (including a Santa Cruz Bullit). They also said to use WD40 to keep it wet and cool.

    The way heat treating works is that you heat up the metal to a certain temperature and then cool it rapidly. This makes the metal harder & stronger (but also more brittle). If you want to UN-heat treat metal (called annealing) then raise the temperature up to it's heat treat temp (~400F for Aluminum) and then let it cool slowly.

    So I think the key to enlarging the seat tube is to "sand" out the material with a honer (cheap at autozone), keep it moving up and down inside the tube (the springs will keep even pressure against the metal), and keep it lubed with wd40 or cutting oil. The key is to not heat up the metal too much and thus undo the heat treat. Take your time, keep it cool, and keep it honer moving up and down to get a nice even shave.

    What do you guys think?

    You've certainly done your research on this one - and it sounds like a reasonable idea. One issue that I can think of is more material will be removed in one part of the seat tube versus some other. I have two thoughts on this matter.

    1) An inside caliper could be used periodically to check the progress being made in various parts of the tube. This would also give the seat tube a chance to cool down. Application of more cutting oil during these breaks would probably also be a good idea.

    2) Perhaps there is some way to limit the expansion of the hone? If so, it could be set for 30.9 mm and you would run less risk of removing too much material from any one part of the tube.
  • 03-23-2011
    DirtyMartini
    Before honing out the seattube, I'm experimenting with another idea. You've heard of "ghetto tubeless"? I'm calling this "ghetto adjustable seat post."

    You've probably seen the old school guys adjusting their seat height manually on the fly: undo quick release, grab seat with inner legs, pull seat up, reclamp QR, etc.

    I could never get the hang of it so I started thinking about how to make the seat go up and down on it's own. What I came up with is the use a gas stut (aka "gas spring").
    These are the little struts commonly used on hatchbacks and windows on cars. They're light, cheap, small, reliable, and come in a wide range of lengths, forces, strokes etc.

    I measured the "stroke" on my seat post (difference between full up and full down) and bought a gas strut with that length stroke at Napa Auto Parts for $30. You want the longest "eye to eye" length you can get without it being so long that when strut is at the bottom of your seat tube it doesn't hold your seat post up higher than you want. It's unlikely you'll find exactly the right length, so error on the side of shorter and then just rig a spacer (pvc or even stuff some old tube rubber) down inside the seatpost to get the right height. The strut will run down inside your seat tube, and up inside your seat post approx 4" below the seat. Oh ya, you'll want either the 20lb force version or the 40lb force version of the strut. (you can buy from 20lbs to 140lb, this is the force required to compress the strut).

    Stand up when you unclamp your QR, the seat rises, sit on it and it does down. You just have to learn to clamp and unclamp the QR on the fly, which isn't that hard if you have a good quality QR (like Salsa). I may post pics at some point. I've tried it out on the street. It works really well.
  • 03-23-2011
    KevinB
    Quote:

    Originally Posted by DirtyMartini
    Before honing out the seattube, I'm experimenting with another idea. You've heard of "ghetto tubeless"? I'm calling this "ghetto adjustable seat post."

    You've probably seen the old school guys adjusting their seat height manually on the fly: undo quick release, grab seat with inner legs, pull seat up, reclamp QR, etc.

    I could never get the hang of it so I started thinking about how to make the seat go up and down on it's own. What I came up with is the use a gas stut (aka "gas spring").
    These are the little struts commonly used on hatchbacks and windows on cars. They're light, cheap, small, reliable, and come in a wide range of lengths, forces, strokes etc.

    I measured the "stroke" on my seat post (difference between full up and full down) and bought a gas strut with that length stroke at Napa Auto Parts for $30. You want the longest "eye to eye" length you can get without it being so long that when strut is at the bottom of your seat tube it doesn't hold your seat post up higher than you want. It's unlikely you'll find exactly the right length, so error on the side of shorter and then just rig a spacer (pvc or even stuff some old tube rubber) down inside the seatpost to get the right height. The strut will run down inside your seat tube, and up inside your seat post approx 4" below the seat. Oh ya, you'll want either the 20lb force version or the 40lb force version of the strut. (you can buy from 20lbs to 140lb, this is the force required to compress the strut).

    Stand up when you unclamp your QR, the seat rises, sit on it and it does down. You just have to learn to clamp and unclamp the QR on the fly, which isn't that hard if you have a good quality QR (like Salsa). I may post pics at some point. I've tried it out on the street. It works really well.

    Yet another interesting idea! After you try it, let us know how well it works...
  • 05-13-2012
    DirtyMartini
    2 Attachment(s)
    In case anyone is still interested in this topc...
    I know this is an old thread but I recently bit the bullet and reamed out my 6point to 30.9mm so that I could install a KS seatpost.

    At first I tried using a brake hone. That wasn't working after about 4 hours of honing I had removed about 0.05mm, not fast enough. Then I bought extra coarse stones for the brake hone, and went another 4 hours and only removed another 0.07mm. At this point I decided that, at least for me, the brake hone method is out.

    I then bought an adjustable reamer and it worked like magic. Very easy. Took less than an hour. Just find a size on the ream that required moderate arm strength to turn the reamer, then give the adjustment nuts a 1/3 turn towards the larger size and run again down through the seat post. You just tap the top of the reamer with a mallet, turn, tap down further, turn until you're down a far as you want. Keep running in 1/3 nut turn increments and you'll be done before you know! Just installed it all. Has a really nice slightly snug fit. The "bore" only goes down to where the top tube joins the seat tube so I'm not too worried about the thinner metal since 1) lots of bikes us a 34.9OD with a 30.9ID 2) many of the Horse link bikes which use a much higher leverage ratio in the rear suspension and thus puts more stress on the seat tube and also use a 34.9/30.9mm seattube. The DW link is a very low ratio, that's why at 185lbs I only use a 350lb spring.
    3) the portion of the reamed seat tube is supported by the cross support (unlike a giant reign for example).

    If it does break it'll probably be a while. If it does break I'll report.

    Attached a couple pictures. I'll probably be looking to sell the ream if anyone is interested. I'm sure I'll never need it again. Maybe we can just pass the reamer around from one to another. Let me know if you're interested in buying it for $40.
  • 05-13-2012
    qbert2000
    Quote:

    Originally Posted by DirtyMartini View Post
    I know this is an old thread but I recently bit the bullet and reamed out my 6point to 30.9mm so that I could install a KS seatpost.

    At first I tried using a brake hone. That wasn't working after about 4 hours of honing I had removed about 0.05mm, not fast enough. Then I bought extra coarse stones for the brake hone, and went another 4 hours and only removed another 0.07mm. At this point I decided that, at least for me, the brake hone method is out.

    I then bought an adjustable reamer and it worked like magic. Very easy. Took less than an hour. Just find a size on the ream that required moderate arm strength to turn the reamer, then give the adjustment nuts a 1/3 turn towards the larger size and run again down through the seat post. You just tap the top of the reamer with a mallet, turn, tap down further, turn until you're down a far as you want. Keep running in 1/3 nut turn increments and you'll be done before you know! Just installed it all. Has a really nice slightly snug fit. The "bore" only goes down to where the top tube joins the seat tube so I'm not too worried about the thinner metal since 1) lots of bikes us a 34.9OD with a 30.9ID 2) many of the Horse link bikes which use a much higher leverage ratio in the rear suspension and thus puts more stress on the seat tube and also use a 34.9/30.9mm seattube. The DW link is a very low ratio, that's why at 185lbs I only use a 350lb spring.
    3) the portion of the reamed seat tube is supported by the cross support (unlike a giant reign for example).

    If it does break it'll probably be a while. If it does break I'll report.

    Attached a couple pictures. I'll probably be looking to sell the ream if anyone is interested. I'm sure I'll never need it again. Maybe we can just pass the reamer around from one to another. Let me know if you're interested in buying it for $40.

    where did you get it?
  • 05-13-2012
    DirtyMartini
    I bought it from Bisco Tool Supply.

    The part number is BP50-J

    Here's the link:
    Adjustable Reamers 1 3/16-1 11/32 11 OAL Adjustable Reamer

    It's the cheapest I found on line. Other places this reamer went for $100+

    After shipping this reamer is ~$50.
    I'll sell mine for $40 shipped.

    You'll also need a "T" tap handle that can accommodate a 0.56" square drivel. Like this one:
    TAP AND REAMER WRENCH 1/4"-1" - Model Number: 12498

    There's probably cheaper tap handles out there. I borrowed one from a friend. You very well may be able to "make" your own by using two adjustable wrenches opposed to one another on the reamer's square drive.
  • 05-16-2012
    LarryLongtravel
    Quote:

    Originally Posted by DirtyMartini View Post
    Attached a couple pictures. I'll probably be looking to sell the ream if anyone is interested. I'm sure I'll never need it again. Maybe we can just pass the reamer around from one to another. Let me know if you're interested in buying it for $40.

    I'm definitely interested in that deal. I have a 2011 Cove G Spot that I'd like to ream out from 30.0 to 30.9. I've spoken to the guys at Cove and they assure me I won't be weakening it significantly (in fact, one of the guys has done it to his own bike). My LBS has neither the tools nor the desire to do it for me.

    PM me and we can arrange payment and shipping.

    Thanks!
  • 05-18-2012
    Gman086
    DM, you are the MAN! If I weren't so broke right now I'd be all over it but I can't afford another dropper post. Keep me in mind tho - I'll eventually get a "real" job!

    Cheers!

    G MAN
  • 06-04-2012
    frgeoff
    Quote:

    Originally Posted by DirtyMartini View Post
    I'll sell mine for $40 shipped.

    hey i need to buy this off you if it hasnt sold yet! please email me geoff[at]full-race[dot]com with your paypal info and ill send payment. my 7 point is begging for a 30.9 right now...
  • 07-23-2012
    BikeSATORI
    Quote:

    Originally Posted by DirtyMartini View Post
    Before honing out the seattube, I'm experimenting with another idea. You've heard of "ghetto tubeless"? I'm calling this "ghetto adjustable seat post."

    You've probably seen the old school guys adjusting their seat height manually on the fly: undo quick release, grab seat with inner legs, pull seat up, reclamp QR, etc.

    I could never get the hang of it so I started thinking about how to make the seat go up and down on it's own. What I came up with is the use a gas stut (aka "gas spring").
    These are the little struts commonly used on hatchbacks and windows on cars. They're light, cheap, small, reliable, and come in a wide range of lengths, forces, strokes etc.

    I measured the "stroke" on my seat post (difference between full up and full down) and bought a gas strut with that length stroke at Napa Auto Parts for $30. You want the longest "eye to eye" length you can get without it being so long that when strut is at the bottom of your seat tube it doesn't hold your seat post up higher than you want. It's unlikely you'll find exactly the right length, so error on the side of shorter and then just rig a spacer (pvc or even stuff some old tube rubber) down inside the seatpost to get the right height. The strut will run down inside your seat tube, and up inside your seat post approx 4" below the seat. Oh ya, you'll want either the 20lb force version or the 40lb force version of the strut. (you can buy from 20lbs to 140lb, this is the force required to compress the strut).

    Stand up when you unclamp your QR, the seat rises, sit on it and it does down. You just have to learn to clamp and unclamp the QR on the fly, which isn't that hard if you have a good quality QR (like Salsa). I may post pics at some point. I've tried it out on the street. It works really well.

    haha, just look up "Height-Rite".
    Those were fairly popular in the late 80's - early 90's. :p





    Quote:

    Originally Posted by DirtyMartini View Post
    I know this is an old thread but I recently bit the bullet and reamed out my 6point to 30.9mm so that I could install a KS seatpost.

    At first I tried using a brake hone. That wasn't working after about 4 hours of honing I had removed about 0.05mm, not fast enough. Then I bought extra coarse stones for the brake hone, and went another 4 hours and only removed another 0.07mm. At this point I decided that, at least for me, the brake hone method is out.

    I then bought an adjustable reamer and it worked like magic. Very easy. Took less than an hour. Just find a size on the ream that required moderate arm strength to turn the reamer, then give the adjustment nuts a 1/3 turn towards the larger size and run again down through the seat post. You just tap the top of the reamer with a mallet, turn, tap down further, turn until you're down a far as you want. Keep running in 1/3 nut turn increments and you'll be done before you know! Just installed it all. Has a really nice slightly snug fit. The "bore" only goes down to where the top tube joins the seat tube so I'm not too worried about the thinner metal since 1) lots of bikes us a 34.9OD with a 30.9ID 2) many of the Horse link bikes which use a much higher leverage ratio in the rear suspension and thus puts more stress on the seat tube and also use a 34.9/30.9mm seattube. The DW link is a very low ratio, that's why at 185lbs I only use a 350lb spring.
    3) the portion of the reamed seat tube is supported by the cross support (unlike a giant reign for example).

    If it does break it'll probably be a while. If it does break I'll report.

    Attached a couple pictures. I'll probably be looking to sell the ream if anyone is interested. I'm sure I'll never need it again. Maybe we can just pass the reamer around from one to another. Let me know if you're interested in buying it for $40.


    Awesome to hear you followed through!
    Just curious, did you disassemble your crank and bottom bracket prior to reaming in order to clean out the shaved off material?

    I may be considering doing this on my MKiii in the near future if I find a deal on a KS...
  • 09-02-2012
    DirtyMartini
    6point ream update: I've been ridding the 30.9mm reamed 6point for the past few months and all is well. Been doing a lot of jumping, shorted a few and had harsh bottom outs but all seems fine so far.
  • 09-04-2012
    frgeoff
    +1, me too, on a 7 point tho
  • 09-04-2012
    LarryLongtravel
    +2 for a BottleRocket and a Cove G-Spot before passing that dirty whore of a reamer on to @frgeoff. Wasn't hard to do, and no evidence of weakening on either after a hard summer of riding. I did remove my crank and bottom bracket, but angling the seattube downhill kept most of the shavings out anyway.
  • 09-05-2012
    Agent Clark
    I did my Mk3 about a month ago, works great. Just took forever with a reamer and drill cause the post needed to go almost all the way into the frame. works great, though.
  • 09-05-2012
    PissedOffCil
    Quote:

    Originally Posted by DirtyMartini View Post
    6point ream update: I've been ridding the 30.9mm reamed 6point for the past few months and all is well. Been doing a lot of jumping, shorted a few and had harsh bottom outs but all seems fine so far.

    Very interesting. 30mm seat tubes are a PITA and I'm looking to ream my Norco Six seat tube as well. How do you make sure the reamer is seated properly in the seat tube and not crooked?

    Thanks
  • 09-05-2012
    Agent Clark
    I just went for it and eyeballed it using a cylinder hone, the kind with plastic balls full of carbide. It took forever with a hand drill, but worked, and didn't need to worry about over doing it. Just had to make sure I went deep enough. (that's what she said) haha
  • 09-26-2012
    rideitall
    I have followed this thread for a while and was moving towards reaming out the seat tube on my 2008 7-Point, when I happened across a RASE 9" dropper post in a 30.0 size.

    Pretty impressive. I am about 5' 10" on a medium 7-Point and ride it on the shore in Vancouver. I try to climb as much as possible and like to be able to drop the seat for steep descents or really tech section, the problem is that my knees object quite strongly when I try to climb with the seat dropped way down (especially after having a dropper post on my trail bike for the last few years). The RASE post lets me adjust the post lower and higher than where I would normally adjust the seat height.

    Works like a charm. Cheers. J
  • 10-01-2012
    rideitall
    7 Point
    Funny how things work out. Just finished posting on the new Rase post, rode it once and now it is going to be sold.

    2 days after posting this, I ended up picking up an almost new Norco Truax, so my trusty Iron Horse 7 point will go to a new owner, same for the Rase post.

    The main thing that pushed me to sell the 7 Point was the HA. Despite having the 1.5 degree angleset and a 180mm fork I was still at about 66 degrees. I could run a DC 200mm fork but want to keep my Talas 180 that is on the bike.

    The Truax with the Talas 80 is 65.5 degrees with a stock headset. I am going to get an cane creek angle set for it and drop it to 64.5. This will be my first non multi-link bike (DW-Link, VPP, Maestro) in many many years going back to a Big Hit that I rode for about 2 months. Should be a fun experiment.

    I have owned a number of IH bikes including three 7 points, one 6 Point and 2 MK IIIs. Not a bad word to say about how the bikes perform. Too bad the original owners of the company were such fools and destroyed it. So good day to the fine IH owners out their and enjoy the rides.
  • 10-16-2012
    bendik.ph
    why not reduce the seatpost from 30.9 to 30.0. wouldn't this be easier to do?
  • 10-17-2012
    the-one1
    Quote:

    Originally Posted by bendik.ph View Post
    why not reduce the seatpost from 30.9 to 30.0. wouldn't this be easier to do?

    Not on a dropper post
  • 03-12-2014
    MrBaker
    Has anyone considered doing this for a Sunday? I'm going to be picking one up soon and while I know they aren't designed to climb effectively, a lot of the DH runs i'll be doing it will involve some flatish/gradual gravel climbs along with some hike-a-biking and would really love to stick my old KS post on it.
  • 03-12-2014
    frgeoff
    i couldnt get any dropper posts to fit in my sunday. if youre going to do some climbing between DH sections, the 7point might be a good bike to check out
  • 03-12-2014
    MrBaker
    Quote:

    Originally Posted by frgeoff View Post
    i couldnt get any dropper posts to fit in my sunday. if youre going to do some climbing between DH sections, the 7point might be a good bike to check out

    What was the issue you faced? Not enough material to ream out? Short seattube? Something else?

    I'm not really interested in a 7point because I already have a 6" travel AM bike and ideally want something for shuttle days/park days in the summer that I could ride in the winters on the local hill at times. Not looking at a lot of pedaling, but I'm upgrading the dropper on my AM bike (KS 150mm Lev) anyway, so I'll have an extra 30.9 i900 KS post around anyway.
  • 03-12-2014
    frgeoff
    the sunday's seat tube is short, so the dropper post can not get low enough.

    I also have a 6" travel 6point as my AM bike, and have had 5+ sundays over the last few years. dont underestimate a properly setup, modernized 7point... and all the sunday parts swap over. i live in Az, we have a good shuttle scene here in phoenix. recently did a frame swap sunday to 7pt and absolutely loving the 7pt. if there is no chair lift to the top, and they are not purposed built DH/bike park trails, i will take the 7pt every time
  • 03-12-2014
    bendik.ph
    that is going to damage the frame. it is better to reduce the diameter of the seatpost or get a gravity dropper which has a size 30.0mm