Deburring Seat Tube

[irideti]

I took delivery of my new titanium frame couple weeks ago, after spending last several years riding carbon exclusively, on and off road. One thing I've noticed is the new frame is putting a zig zag mark on the seatpost during height adjustment which my carbon frames would not do. Does this mean I need to deburr the seat tube? If so what would be the easiest way?

I remember this happened to those steel, aluminum or titanium bikes I owned before. But for some reason I did not care as much as now.

[bikinchris]

Yeah, go by your local shop and they probably have a drill with a ball hone to deburr your seat tube.

[guyintense]

Or find a bike shop with the best tool for the job.

[oliver1850]

I have cut a slot in a wooden dowel, loaded the slot with sandpaper, and spun it with a drill.

[paredown]

Originally Posted by oliver1850

I have cut a slot in a wooden dowel, loaded the slot with sandpaper, and spun it with a drill.

^^This^^

Also check the edges of the slot, and the edges of the seatpost clamp--I'll used a little 200 grit wet-dry folded multiple times into a narrow, somewhat stiff strip, and carefully go over all the edges.

[unterhausen]

A ball hone is the best tool for the job, not a reamer. I suppose a reamer might work, but will probably still leave burrs.

I suppose you could wear the bore catywumpus, but getting rid of a burr will not do that.

When I bought one, a ball hone the proper size was about $30, haven't checked recently.

[FriarQuade]

ball hones are great for removing grit, crud or oxidation from a seat tube or other bore. But to remove a burr that's causing seat post scarring you're better off going after the single burr with something more focused, a file, flap wheel on a rotary tools or maybe just some sandpaper. Using a flex hone will ultimately enlarge the seat tube slightly by the time the burr is gone and it's really a second rate solution. Maybe it won't hurt anything but it could turn your otherwise perfectly good bike into one with a chronically slipping seat post.

[unterhausen]

I have tried to enlarge a seat tube with a brand new ball hone and it didn't do anything. If a builder left a burr, they probably left reamer chatter too. Ball hone will clean that right up. I would hate to let the average person loose on a frame with a file.

[irideti]

I inspected the interior wall of seat tube carefully and found a small but sharp burr. The position of this burr matches to the mark on the seatpost therefore this is the one I need to smooth out. I think file is a good tool to smooth out a single burr in this size but I'll let shop mechanic to decide.

IMG_5695 4 by ipenguinking, on Flickr

[oldpotatoe]

Originally Posted by unterhausen

A ball hone is the best tool for the job, not a reamer. I suppose a reamer might work, but will probably still leave burrs.

I suppose you could wear the bore catywumpus, but getting rid of a burr will not do that.

When I bought one, a ball hone the proper size was about $30, haven't checked recently.

If it's a YUGE burr, not uncommon where the seat stays are welded, 'maybe' a reamer first, making sure ya don't take too much off, followed by a ball hone.

[witcombusa]

I'd be in there with a mill smooth half round file.
Then I would use some 220 Emery to do general clean up inside.

[dddd]

I agree with the approach using a half-round file. Super-easy and hard to eff up, just don't bevel the opening edge in the process.

Done this before on steel frames with a blob/drop of brass down there, got my Steyr (Austrian) bike to take the intended 25.6mm post instead of a lumpy steel post or an undersized 25.4mm alloy post.

I don't have a picture of the inside of the seat tube, but oh well here's the bike:

[guyintense]

A reamer is always going to be more accurate than a ball hone. If set up properly the reamer will remove only the high points. The ball hone is less discriminant, removing the highs and lows at the same rate. I'd be more inclined to use a brake hone for the final cleanup.

[irideti]

So this morning I installed an old post and rode to my LBS. My trusted mechanic took out the seatpost, inspected with his finger and eyes and said there is no burr. I did not believe him so I also inspected it myself and the burr is gone. I came home and installed the new seatpost, pulled it out few times without putting marks nor scratches. I guess it wasn’t really a burr but metal flaks.

[guyintense]

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