seat post sizing dilemma advice

[Allnnn]

Hey guys, im a long time lurker ready to jump into this forum.

I bought an 80's frame with a seized seatpost that the previous owner tried to hacksaw out. They didn't manage to get it out, but sure did scrape the frame with the blade. After a whole bottle of lye, i finally destroyed the aluminum seat post. i didnt measure the diameteer of the post that was previously stuck and now with a warped seat tube hole, using a caliper is pointless. I found a 26.8 seat post that a tried with some luck. The post went in easy at first ( because the beginning of the seat tube was forced wider with whtat ever the PO did to the framing trying to get the post out), but then you have to twist it back and forth to make it go down further. It is really tight. My question is: should i try a 26.6 seatpost or would that just slip in the seat tube? I am hesitant to try because the braze on clamp wasent even clamping a 26.8 seat tube so obviously it wouldnt clamp a smaller post with out some adjustments. should i just run a 26.8? if the frame was indeed meant to take a 26.8 post,is it normal to be that tight? i dont know what to do anymore. Any advice would be greatly appreciated! thank you.

 

[TreaderSteve]

What frame is it? If it's MTB someone on this part of the forum may well know off the top of their head. As for the situation above it sounds a bit fooked. If it doesn't clamp with the right post, without sending it off to a frame-maker, you could I suppose lop off the braze-on clamp and use an external clamp.....
Pictures?

 

[kingoffootball]

Did you give the inside of the seat tube a could clean up afterwards? If so, I would suggest 26.6 but if not a clean and light sanding might make 26.8 just right.

 

[Allnnn]

What frame is it? If it's MTB someone on this part of the forum may well know off the top of their head. As for the situation above it sounds a bit fooked. If it doesn't clamp with the right post, without sending it off to a frame-maker, you could I suppose lop off the braze-on clamp and use an external clamp.....
Pictures?

Yeah it’s an 87 Panasonic Mc-6500. I’ve searched everywhere on the net for posts including that frame and none of the few I found stated the diameter size. There isn’t much space for the braze on to be eliminated.
My next step would be to somehow fix the shape of the seat tube and just keep the 26.8 and done. Then maybe try out a quil seat post which I never knew they existed but the few on eBay are to short in length. And if all else failed I’d just get a welder to permanently seal a post to the frame. I’ll take some pictures when I’m back.

 

[Allnnn]

Did you give the inside of the seat tube a could clean up afterwards? If so, I would suggest 26.6 but if not a clean and light sanding might make 26.8 just right.

I used a deremel with a sanding tip but I wasn’t thorough with the clean up.

 

[Ippikin]

I imagine the seat lug clamp has been distorted by various seatpost extraction attempts, have you tried closing it back up without the seatpost fitted, that may help it grip as would a picture on here if you are unsure. As for seatpost I agree that a 26.6 should fit if a 26.8 doesn't.

 

[Woz]

If you know the bike, you could know the tubeset and go from there to find the "right" size post.

That said, it's a nightmare once the seat cluster is damaged.

Going for a 25.4mm post and using a softer AL shim to 26.8mm isn't a bad way.

Lots of grease, and some sanding off the shim if necessary.

 

[Allnnn]

If you know the bike, you could know the tubeset and go from there to find the "right" size post.

That said, it's a nightmare once the seat cluster is damaged.

Going for a 25.4mm post and using a softer AL shim to 26.8mm isn't a bad way.

Lots of grease, and some sanding off the shim if necessary.

The frame has tange mtb tubing. I looked it up and I believe it said 28.6 s.b.t. On tanges catalog. . No clue what the abbreviation is.

 

[Allnnn]

I imagine the seat lug clamp has been distorted by various seatpost extraction attempts, have you tried closing it back up without the seatpost fitted, that may help it grip as would a picture on here if you are unsure. As for seatpost I agree that a 26.6 should fit if a 26.8 doesn't.

They only thing I worry about using a 26.6 is that I will be a bit too loose and the clamp not doing it’s job.

 

[Woz]

They only thing I worry about using a 26.6 is that I will be a bit too loose and the clamp not doing it’s job.

Don't go smaller. Makes matters worse. 25.4 - 26.8mm makes more sense.