sac02

OK I'll do my best to describe this. I am replacing the steel seatpost on my Peugeot UO-8 conversion with an alloy post. The seat tube is 25.4mm (so is the alloy post) but the original steel post is something like 22mm with a shim.

The problem is that there is a raised seam of metal on the inner diameter of the seat tube - like a "ridge" running down the back of the inside of the seat tube . (It's a cheap old bike and I'm assuming the tubing was rolled and then welded along this seam rather than the tube having been extruded or drawn.)

Anyways, with the original 22mm+shim setup, this seam of metal was a non-issue. But now that I'm trying to fit a 25.4mm post in a 25.4mm tube, this seam is creating interference, and I can't get the post in the seattube more than about an 1.25inches.

What, in your professional or non-professional opinion would be the best way to remove a raised seam of metal on the inner diameter of a 1inch tube? I would like at least 3 or 4 inches of seatpost insertion. My dremel can only reach about 1-1.5inches. Would a "pencil" extension/adapter for the dremel be the best plan? A round file?

Thanks for the help,

Mac

MarkWW

On my UO-8 I actually just lathed the 25.4 seatpost that I got down to 25.0mm and it worked like a charm. Supposing that service isn't available to you, i'd say use a half round file. And if you're still using a cup and spindle setup for your bottom bracket, be sure to clean it afterward, as I'm sure metal shavings will have fallen down there.

potus

you can make an extension for your dremel using a piece of .125" steel rod. cut it to the longest length you'll need (plus a little more to clamp into the dremel). using black electrical tape build up the end of the steel rod far enough that you can using one of the dremel sanding tubes. becareful starting and stopping your dremel with this frankentool on. it's best to have it already against the piece you're sanding so it doesn't get all helicopter and smack you in the face.

jacobs

Use a seat tube reamer, or turn down the post.

If the OD of the ST is 25.4, you shouldn't be putting a 25.4 seatpost in it. On a bike of that vintage, you'd probably want a a 24.2 or so.

sac02

ID of the seat tube is 25.4, not OD

Other people have used 25.4 seatposts on this bike, and the post is a perfect fit until is hits that seam; it is the right size post.

Regarding the seatpost reamer - I didn't know those existed. I hope my LBS has one, it certainly sounds like the easiest option, even if it costs me a couple bucks.

Mac

Retem

I would say if its more than 5 bucks its a waste the uo8 wasn't a very good bike to begin with stick to the nishiki / univega types or the px series something more worth the effort

Landgolier

seat tube reaming is one of the most PITA frame prep operations, but it can be done. Use a ton of cutting oil, and pull the BB first and put a rag in there. Otherwise you just fill the BB shell with shrapnel.