27/27.2 - has my seatpost been wrong all along?

[swee'pea99]

Eventually managed to get the seatpost out of the frame - what a struggle. There was no corrosion or sticking - nothing like that - it was just incredibly tight in the tube, and needed to be revolved back and forth, back and forth, back and forth all the way. It took a very strong man a lot of effort to do it (I couldn't, period).

The markings say it's a Shimano Max, 27.2. It came with the bike when I bought it second hand (and is now broken, hence the removal). I was wondering whether it might be possible that the frame actually needs a 27, not a 27.2 - and that accounts for the tightness. Or is that impossible - if the frame wants a 27, a 27.2 simply wouldn't go in. Or would go in only with actual shavings coming off.

Before anyone suggests, I'm not taking it to my LBS. They're nice, but they sell £70 carbon seatposts to corporate lawyers. I'm thinking more in terms of 99p + £3.00 p&p off ebay. I'd just appreciate anyone's thoughts on whether a 27 or a 27.2 is likely to be my better bet.

 

[mickle]

It's a 27.2 if a 27.2 came out of it. There's no debate.

Clean the inside of the seat tube as much as possible and give it a good smear of grease before installing the new post.

 

[fixedfixer]

What make of frame? Sheldon Brown has a database of sizes by manufacturer and year. Could help you find out what is required.

 

[mickle]

What make of frame? Sheldon Brown has a database of sizes by manufacturer and year. Could help you find out what is required.

It's 27.2.

 

[swee'pea99]

I'll go for a 27.2 then. Thanks! FWIW, it's an old Dawes frame, which isn't specifically listed on Sheldon's database (which I had checked out, tho' thanks anyway), tho' he do say that Dawes old racers generally use either a 27 or a 27.2. Imagine my surprise.

 

[fossyant]

Make sure you give the seat tube a good clean.

I can tell you a 27.2 post will not go in a 27.0 seat tube - no matter what - tried it then realised the old markings on the old post were 27.0 - the .0 was hard to read. All my other bikes are 27.2 - this one is Tange cro-mo though. Got out the vernier claipers to check.

 

[PpPete]

Old steel frame ... you can make life slighty easier on removal & refitting a seat post (as well as the advice given above) by opening the slot a tadge. A really big flat blade scewdriver between the "ears" that hold the bolt is best, twist it carefully though, you can do more damage opening it too much than you can "closing" it up too much because you installed a too small seat post.

And don't even thing about doing it on an aluminium frame.

 

[MacB]

maybe try a different seatpost - allegedly some makes come up different, I've seen a few comments that the Thomson brand are more svelt than others in the same sizes.

 

[biggs682]

if somebody had put a 27.2 in to a 27 frame then it would not have come out easy at all , so go 27.2 as a 27 might not clamp up

 

[mickle]

if somebody had put a 27.2 in to a 27 frame then it would not have come out easy at all , so go 27.2 as a 27 might not clamp up

It's simply not possible. At least not without a steam hammer and the total destruction of the frame.

 

[GrumpyGregry]

It's simply not possible. At least not without a steam hammer and the total destruction of the frame.

I recently came across a rather lovely high-end early 90's Kona Explosif mtb for sale on which the numpty owner had tried to stuff a contemporary 27.2 post down a teenage 27.0 tube. At one point they proudly told me they had used a club hammer but they couldn't get it past where the top tube joined the seat tube...


... so they took a hacksaw to the seat post and shortened it, leaving about 2" in the short section of seat tube above the top tube junction.

I walked away after pointing out the crack in the seat tube.