# can i ream a seatpost tube



## rc51kid (Jul 24, 2008)

i am asking this here becouse i figure you guys might know. I have a 95-96 ish (old) Gunnar Rock Hound. It usses a 27.0 seatpost. I want to ream it to 27.2. Gunnar does not think it is a good idea. They think it might couse slipping problems. I would really like to be able to use all of the 27.2 seatpost that are around. What do you guys think of reaming it to 27.2? Any ideas of the best way to do it or the best builder to do it? I would almost rather do it myself than trust it to just some local shop. I would also be willing to ship it to a VERY good builder if that is what it takes to get it done right.


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## j-ro (Feb 21, 2009)

Thomson makes both a 27.0 and a 26.8.

In my opinion you would be money ahead just buying one of them vs. buying the tools to ream or paying someone to do it and then still having to buy a new seatpost.

The other issue is that once the slot is cut reaming accurately becomes a little more difficult. The reamer tends to just 'push' that area out of the way while cutting below the slot. This can make it look bulged.


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## rc51kid (Jul 24, 2008)

j-ro said:


> Thomson makes both a 27.0 and a 26.8.
> 
> In my opinion you would be money ahead just buying one of them vs. buying the tools to ream or paying someone to do it and then still having to buy a new seatpost.
> 
> The other issue is that once the slot is cut reaming accurately becomes a little more difficult. The reamer tends to just 'push' that area out of the way while cutting below the slot. This can make it look bulged.


Sounds like good info. But, i can fit the 27.2 post about 1/4 inch past the split. So i dont know if i would have to ream that area. Also i have a 27.2 Thompson Masterpeace already that i want to use. 
Also i have to look, but i might have access to some reamers. I dont know if they are the right type, i would have to look.

I am more than willing to go get a 27.0 thompson Elite if that is the best way. But i would love to be able to use some of the really nice carbon posts and nicer Thompsons if i could.


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## Walt (Jan 23, 2004)

*Use the 27.0*

Why do you need/want a fancy seatpost on a 16 year old Gunnar? Stick a Thomson on it if you want something nice, or a Kalloy if you don't, and go for a ride. I'm pretty sure after about 30 seconds of singletrack you won't remember or care what kind of seatpost you've got.

-Walt


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## GrayJay (May 16, 2011)

If you want to use your existing seatpost, it is pretty easy to reduce the OD of an alu post slightly just using sandpaper wrapped around it. A reduction of 0.1mm from the seatpost walls is probably fine if it is not already beer-can thin. You can also use a piece of sandpaper rolled into a tube to cleanup any imperfections inside the ST so that you dont have to reduce the OD of the seatpost quite so much.


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## Yogii (Jun 5, 2008)

Neither is a good idea, but sanding the seatpost is WAY better than reaming you seat tube! Better yet, do as Walt says and get the right size! Sell your old post.


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## customfab (Jun 8, 2008)

I've done this to a couple of older Kona frames that also used that 27.0 size. Turned out just fine. Any half serious frame builder should have a reamer. Find one in your area and go to town, just don't ream it to much obviously.


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## TimT (Jan 1, 2004)

I've done this also on a couple of frames for the exact same reason. (use of carbon post) 
.2mm =.0078" Not much and don't have to go all the way down the seat tube.

Tim


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## lew242 (Aug 7, 2008)

I've done this taking a 30.2 to a 30.0, but by sanding, and so has a friend. Basically you can do it only if you are going to use the bike at one specific height and don't plan on changing the height with a quick release on rides. If you do dirt will play havoc with your seat post and it will probably get stuck badly. Don't know about reaming, but I'd get a proper sized post if possible.


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