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  1. #26
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    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.

  2. #27
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    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.
    Last edited by marshallmthomas; 10-01-2010 at 12:27 PM.

  3. #28
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    Anyone get their seatpost reamed yet?

  4. #29
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    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..

  5. #30
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    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).

  6. #31
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    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. :-/

  7. #32
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    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.
    speedub.nate
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  8. #33
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    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.

  9. #34
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    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?

  10. #35
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    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.

  11. #36
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    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.

  12. #37
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    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...

  13. #38
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    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.
    Attached Thumbnails Attached Thumbnails Anyone ream out the seat tube to 30.9 for adjustable posts?-30.9-6point-mtbr-size.jpg  

    Anyone ream out the seat tube to 30.9 for adjustable posts?-30.9-6point-mtbr-size-reamer.jpg  


  14. #39
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    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?

  15. #40
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    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.

  16. #41
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    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!

  17. #42
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    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
    "There's two shuttles, one to the top and one to the hospital" I LOVE this place!!!

  18. #43
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    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...

  19. #44
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    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.





    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...
    Schralp it Heavy.

  20. #45
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    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.

  21. #46
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    +1, me too, on a 7 point tho

  22. #47
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    +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.

  23. #48
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    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.

  24. #49
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    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
    Check out my SportTracks plugins for some training aid software.

  25. #50
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    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

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