restored frame, cant get the seat post in....

Neil Fat man on a bike

Hi guys,
I've just had a Mercian 531 frame restored.
It looks great but I've got one major problem.....I can't get the seat post in.
It's a new 27.2 mm diameter seat post.

Q1 is this the right size? surely Mercian wouldn't have sent the wrong one out !!?? :evil:

The original seat post is way too slack, I'm wondering if the tube has been crimped slightly in the past by being tightened down on to this old seat post.

Q2 what the hell do I do to get the new post in? Wet and dry cloth the inside of the tube? Wet and dry the outside of the seat post ? Try and spread the tube ?

Any suggestions ?

pneumatic

Phone Mercian and get them to send you one or more smaller ones. When you get one that fits, send the rest back.

I had this problem when I did up a friend's bike and a millimetre turns out to be a big thing when it comes to seat posts.

Neil Fat man on a bike

Yes, I think that is probably the first course of action,
Now that I have removed the overspray that is...........
cheers pneumatic

Neil Fat man on a bike

Just tried a 26.8 and that's too small....looks like a 27mm is what I'm after.

robbarker

I was just about to say it will be a 27.0 but now noone will believe me!

Neil Fat man on a bike

Thanks Rob, I'll beleive you mate

mekonta

I recently got a renovated Mercian frame back from them and had a similar sort of problem.

I'm pretty certain you have a 27.2 - I think all their frames are this size.

I found a couple of little burrs on the inside of my seat tube which came off easily with a bit of sanding.

But I did have to put a bit of effort into getting the post into the frame which was a bit disconcerting at first but once in it's no problem. Just put plenty of anti-seize on!

pneumatic

Once you get one that fits, make sure you can get it to stick in place.

I got so frustrated during the above rebuild that I took the seapost out of my tourer to see if it would fit. It didn't so I put it back into the tourer and tightened up the bolt.

The next few times I rode the tourer I got really sore legs as the seat slipped gently downwards and my knees spread wider and wider. More than once, I nearly broke my hand trying to tighten up the bolts holding it in place, but to no avail. It still subsided on every ride.

Then someone told me to take out the post, grease it and put it back. This seemed to me to be insane as it was slippery enough as it was. However, I did it and they were right. It hasn't moved a millimetre since. I still don't understand why, but then I am not an engineer.

robbarker

I had a very old mercian framed bike at University about 20 years ago, but in immaculate nick. I slowly did it up and bought a shiny new alloy seatpost for it, thinking in my naivity they were all the same size! It turned out the (27.2) post was too big - the Mercian was a 27 (might even have been 26.8 but a 27.0 seatpost ended up in there!)

Neil Fat man on a bike

27 mm one should arrive in the post today( not from Mercian though, it would have been their standard 2 weeks from stock room to post bag :evil: ) Fingers crossed, the other vexing thing is that the allan key bolt ( should be 5mm allan key ) is sloppy on a 5mm and too big for a 6mm key !!!!

Neil Fat man on a bike

Seat post is now in.......but not yet tight due to above !

munster

Have you tried imperial allan keys?
You never know you might get a better fit.

Neil Fat man on a bike

Not yet.........but I bet that is it. It's a second hand bike and the clues look to point at pretty old.

Cheers