I would recommend you get the appropriately-sized adjustable one from Bike Tools Etc.
Their basic one for the typical range of vintage bikes' posts is $78. They have an HSS version for about $200, but I doubt you will need that.
Once you get it set to where you want it (27.2 in this case) then just leave set to that diameter.
I have one, and have used it literally hundreds of times. I just recently bought a smaller-diameter one so I can set that one at 22.2 mm for steerer tubes.
And yes, do the reaming with the frame's BB shell higher than the seat lug, so the small particles (that don't stick to the reamer, use lots of cutting oil!) can fall out into a waste receptacle of your choice....
Greg Parker Ann Arbor, Michigan http://www.bicycleclassics.com
Date: Sun, 27 Apr 2008 12:21:05 -0500 From: John Thompson <johndthompson@gmail.com> To: classicrendezvous@bikelist.org Subject: [CR] Seat tube reamer
Johnsons wrote:
> Purpose made seat tube reamers can be difficult to find in the required
> sizes and if you find one they can have disastrous results if not used very
> carefully indeed.
An adjustable reamer (size "I" IIRC; I'm not near my shop at the moment)
works well for reaming on-topic frames.
> I always push some cloth way down the seat tube first to stop metal
> particles dropping down into the bottom bracket area. When finished I turn
> the frame upside down to remove the cloth and the filings.
Most of the frames I ream are bare, but if not I usually ream the tube with the frame held upside-down, so the particles drop out of the tube. But the cloth is a good idea.
--
-John Thompson (john@os2.dhs.org) Appleton WI USA ------------------------------
Date: Sun, 27 Apr 2008 10:25:09 -0700 From: "David Joshel" <davidjoshel@hotmail.com> To: "Anthony Kinder" <antct1@tpg.com.au>, <classicrendezvous@bikelist.org> Subject: Re: [CR]WTB:Seat Tube Reamer 27.2mm
Hello All,
for cleaning/deburring seat tubes have had good results with this method. Find a wooden dowel ( broom handle ) close in diameter to the seat tube. Tightly wrap 100 grit sandpaper around the dowel until it's just slightly smaller than the tube hole, and use it to clean the inside of the tube by moving it back and forth inside. Blow it out with canned air or clean with a damp rag to get dust/ metal particles out.
Dave Joshel
Davis CA usa
> Hi all,
> Am looking for a fixed size reamer to clean out seat tubes. Generally
> all work is on Colnago frames so needs to be 27.2mm. (I make 1.07087")
> I don't know if that is the exact size of the reamer or if it is a
> smidge larger.
> I had enough of standing over a frame and putting most of my 200lb mass
> onto a seatpost only to end up with a ghastly zig-zig down the pole even
> with suitable lube.
> Help, advice and tools for sale greatly appreciated as always.
> Anthony Kinder
> Perth, Western Australia