Seat Post re-sizing
 

Anyone here ever taken a seat post to a machine shop for re-sizing? When I mean re-sizing I mean taking a lathe and milling it down in size. I have a beautiful NOS Fluted SR Royal seatpost that's a 26.8 and I need a 26.6. I was thinking of taking to a friends' machine shop and milling it down to a 26.6 which is only .2 tenths of a millimeter or .0078 up only to the insertion line. He's done this before for one of his workers bikes and says it's a piece of cake. Any comments? Here's a pic of the post.

I have and it is not real hard to do. Roger

Roger. thanks for the vote of confidence but now that the bike is delivered I checked the existing seatpost and it's 26.4 so now it would be a change of .4mm. Is it still save to mill it down to that size without compromising the integrity of the post? I know some may just get a post that fits, but this seatpost is NOS and would put even the Campy seatposts to shame IMHO. Here's a couple of pics to the one I have and a link to more pics. It's the totally fluted one.

http://www.wooljersey.com/gallery/main.php

It being NOS could be a case Against milling it down. I would be more inclined to do that to a used post rather than a NOS one. I would think the value of the post in its original condition and size would be higher than as a milled down unit. Of course, if it is going to stay on that bike forever and ever, then no big deal, but the post is still worth more in its original size than milled down, even if it is no longer NOS. But in the end, it is up to you what to do with it, and milling off .4mm should not damage integrity, they are pretty stout posts. As for milling only to the limit line (which would make sense aesthetically), that pretty much leaves you with only that option, fitting it to the limit line. It would go in no further, if, for instance, you wanted to have the post farther in (lower seat) for your particular needs and application,,,You would be stuck with the amount of seatpost you milled it to.

Actually, since your milling "both" sides of the post, you're only taking 0.2mm thickness off. The post would probably take it, but I think I'd look for a correct one first. I've sanded a 27.0 down to a 26.8 before. Started with 60 grit and gradually moved to finer grits and steel wool. Looked great but it was a cheap non-fluted post to start with.

How deep are the flutes, and how good do you envision them looking 0.2mm shallower? (May not be able to tell that little amount in reality)

As for the flutes, pretty deep and I wouldn't go as far as the flutes. My thoughts were to go just above the insertion line and then taper to the flutes. I've already measured where I want the seatpost height to where I want it. Anyways, I'm never going to replace the seatpost after that because it took me forever to find this particular post. Problem is they never made this particular one in a 26.4. The smallest they made was 26.6.

I'd do it with no worries. In fact, if I was in a hurry and had a few I'd do it with a flat mill file ;)
Top

I've done it more than once with a Porter Cable 1/4 sheet pad sander, then steel wool and then a final buff on a cotton wheel and rouge. You have to be careful to sand evenly all the way around the post to keep it round. Nobody will ever know you've sanded it.