So I have a frame that takes a 31.6 post but it wont fit in. Tried a 30.9 post and can tell there is more play 4 inches or so from the top of the seat tube than at the top so it look like the top around the clamp area has closed up a tad.
How can I open it up a tad without breaking anything?

Cheers.

Got a couple of posts to try? Especially if either frame or post is from on one.

Assuming it’s a regular post (check it is actually 31.6 also…) not a reverb I’d file a chamfer on to the edge of the post, grease it and it should go in with a bit of persuasion.

What frame is it bud?

If it’s an older frame it could be pretty much anything! Selling seatposts in the 90s was a nightmare….

I had a similar problem. Tried the next size down and it slopped around. Drove me nuts.
It was only going to be a pub bike and it would not open up to allow the correct size. In the end I made my own reamer with a digital vernier to make sure it was the correct size,attached it to a drill and cleaned it out.
Worked a treat, you need to be brave to try it.

Planet x/on one frame?

Go a size down on the seatpost and bodge a shim? Or get an actual shim a smidge small and pad it out with coke tin. Etc.

It’s a second hand frame that takes a 31.6 post.
It definitely is narrower at the top as if the seatpost clamp been tightened without the post being in the tube.
Just wondered if there’s a way to wedge it open safely at the top where it’s closed in a tad?

Just gently lever it open with a flat screwdriver or similar tool. Or get a smaller seatpost and insert it an inch or two and roll it around to open the top of the seatpost out.

Take it to a bike shop with a reamer?

Suspect that the tube has been ovalised, so reaming might not help. Ideally use a slightly-tapered tube to see if you can get it a bit more round e.g old seatpost and lots of grease – use of a reamer will depend on how out of round it is

Just gently lever it open with a flat screwdriver or similar tool.

FFSdo NOT do that.
I’ve seen this loads of times. The best way is to use a really cheap seat post, the Ines with the separate clamps off BSOs, and pop the thin end in the bike and gently roll it round at an angle to open the top of the seat tube out.

granny_ring – Member
It’s a second hand frame that takes a 31.6 post.

Aye, but what is it and material is it made of – carbon?

Cheers guys, I’ll try with a smaller post and roll it around with plenty of grease.
Frame is ali.

PP, sent you a msg thanks.

Planet x/on one frame?

Wizards sleeve?

Planet x/on one frame?

No

Update.

Tried the smaller seat post thing and it’s opened the seat tube slightly, I can get the post inserted around an in but that’s it.

So is the next step taking it to a LBS to see if they can ream it out?

If the post is only going in that far after you’ve been trying to expand the top of the seat tube then I have my doubts that it’s really a 31.6 seatpost you should be using.

It’s fairly normal for seat tubes to widen out after 4″ or thereabouts so don’t let that fool you into thinking it should ALL be wider.

And why so reticent about identifying the frame? If folk knew what it was then they might have some relevant information.

Fair point. Frame is a 2014 Trance. I’m thinking you might be right but I was told it’s 31.6 a 30.9 seems a bit loose.

Giant are usually 27.2 or 30.9 IIRC

2014 trance is 30.9. I know that for a fact, got a giant dropper for one.

I was going to post earlier that if your getting an inch in and it’s stopping after you’ve opened it out you’ve definitely got the sizing wrong.

30.9 seems a bit loose.

might be a lot loose now! Coke can shim could be in order.

Just googled and seems to suggest it’s 30.9…

https://www.giant-bicycles.com/int/trance-27dot5-2-2014

Quickly – someone post a Facepalm meme…

As above Giants are 30.9

LOL. I was going by what the previous owner told me…I thought they might know 😯 I did a google as well just now….hey ho.
To be fair the 30.9 felt loose in the frame before I started the cock up
so I’ll try and fix it tomorrow albeit with coke can shims or not!

Now you need a decent clamp:

Recommend salsa if you can find one.

Too late now but most modern mainstream frames are easy to find sizing for. Always worth a Google or a question on here. Or verniers…

A good clamp it’ll be fine

I’ve got a hope bolt up clamp I’ll try first off.
Cheers for advice guys and hope I’ve cheered you all up 😀

Clamps bolted up fine, and nick, I’ve sent you a message on here.
Thanks.