THE SEAT TUBE CAVITY

Lets start with what is, in my estimation, the greatest offender of the three - the seat tube cavity.  This cavity is the part of the seat tube that accepts the insertion of the seat post.  I see this area as an offender because it experiences frequent attention, often times at the hand of a mechanical novice.  Not knowing how to maintain this mechanical system causes damage.  Damage, not only to the seat post, but also to the frame set as well.

Properly maintaining the seat post cavity is easy to do.  Ensure that the seat post is lubricated with a light coating of grease prior to installation.  Always use a proper wrench to tighten up the seat post clamp bolt.  And keep the post and inside diameter of the seat tube clean. That's about it.

Install the seat post without grease and it is likely to seize itself into place.  A seized seat post is a nightmare to remove.  Failure to use the correct wrench will eventually scratch the paint in the area of the seat post clamp bolt, or worse.  Worse?  Chances are good that the wrong wrench will actually gouge the metal or crush the top of the seat stay.  And failure to keep everything clean will lead to the need to over tighten the seat post clamp bolt to get the seat post to hold in position.

The seat post lug and cavity, on this mid seventies Peugeot PR10 something or other, looks bad and really is bad.  In fact, this seat tube lug is about the worst one that I have ever seen.  The clamp bolt had been over tightened, stretching the bolt hole.  The seat clamp bolt itself has been tightened to the point where it too is bent.  Now, the bolt will not even pass through the elongated and squashed hole.  Gentle, but firm, repair is necessary to get this working, and looking, the way it is supposed to.

Now, the damage seen here is not, and I repeat not, uncommon.  This type of frame damage is the most common, of any that I see.  But what really bothers me about this PR10 example, is the incredibly poor workmanship displayed by the craftsman(???) who built this fairly high end French bicycle.  The seat lug looks bad and thanks to its sharp edges, is also dangerous.  And then there is the gap at the point of the seat post lug.  A gap where the brazing did not take.  In all fairness to Peugeot, I see this kind of sloppy workmanship in many other, so called, quality bicycles.

Before going any further with refurbishing this Peugeot PR10 frame, the seat post cavity needs a bit of work.  Once the clean up effort is complete, the cavity will be clean and reasonably round.  The bolt holes will allow the clamp bolt to pass through easily and the cavity will not scratch up a delicate alloy seat post when being inserted, adjusted for saddle height or removed for further maintenance.

NEXT - PREPARING THE SEAT TUBE CAVITY