Bicycle Mechanics - Seat post too big?

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cooleric1234
08-12-10, 09:40 PM
I just made another post in which I mentioned my wife borrowed a bike and I'd like to fix it up before returning it. One problem she had was the seatpost slipped down while riding. It's probably my fault, it's a carbon post and I was worried about over-tightening it. I did notice, however, that the post was VERY hard to move up and down. I loosened the bolt on the collar all the way but I'm having a very hard time removing the post just to take it to a bike shop to get the nicks checked out. I've never dealt with a carbon post (aluminum frame, Tirrenno Razzo 3.0) but I wonder if it should be that tight? It looks like it's leaving lots of tiny scratches as I try to remove the post. Is it possible it's too small for the frame just by a little bit? Obviously it can somewhat work, but I wonder if that was part of the problem. Most of the grip just comes from it being in the frame so I thought it was tightened enough.

FBinNY
08-12-10, 10:15 PM
If the post can slide in to the seat tube beyond the the slotted first 1-2 inches is is definitely not too big. The next size won't fit at all, and the next one smaller would be sloppy ,and possibly couldn't be tightened. the scratches are probably from burs and rough edges created when they milled the slot in seat lug or clamping area. They can be filed out with a triangular or half round file to keep from adding more scratches.
cooleric1234
08-12-10, 10:19 PM
If the post can slide in to the seat tube beyond the the slotted first 1-2 inches is is definitely not too big. The next size won't fit at all, and the next one smaller would be sloppy ,and possibly couldn't be tightened. the scratches are probably from burs and rough edges created when they milled the slot in seat lug or clamping area. They can be filed out with a triangular or half round file to keep from adding more scratches.

Okay thanks. I wouldn't call it "sliding" into the seat tube, more like "it fits if I push real hard." But it sounds like that's just the nature of this beast. The fine scratches (makes the black carbon post look milky) are all around the seatpost, not just at the slot area. That's part of why I thought it might be too big.