Seatpost shim - a bad idea?

[Bencolem]

So unfortunately I've had to abandon a bike build that's been months in the planning and am now starting anew with a different frame.

Problem is, the new frame (Parlee Z5) takes a 31.6mm seatpost.

The seatpost I bought for the original build (Enve) is 27.2mm.

What do you think to running a seatpost shim? Thinking a narrower post will be more comfortable but conscious a shim could seize or create unwanted stresses?

[R3awak3n]

I would start by posting a WTT here on paceline. I had a 31.6 enve post that would have traded for a 27.2 so maybe someone here does as well.

I bet shims work but I don't like shims, specially between carbon

[charliedid]

Buy the proper size post.

[ntb1001]

Shims exist...but I would just get the right size.


http://www.wigglestatic.com/product-...t-shim-med.jpg

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[El Chaba]

I really don't like shims and prefer the parts to be properly sized to fit one another. If the shim is something like the purpose made ones like USE makes (or made) they really aren't that bad...I'd hit everything with carbon paste in an effort to avoid creaking as shims introduce another interface that has the potential to make noise or have a galvanic reaction...

[ultraman6970]

I will tell you, depending on your budget and the 27.2 model and brand I would consider the shim.

About the shim getting stuck just put grease between the frame and the shim and then carbon paste between the shim and the seatpost and you should be ok.

BTW im thinking in a good shim ok? like USE for example, some shims are made of hard plastic aswell, other ones are metal, some have a lip at the top, other ones dont, I would pick one with a lip.

Good luck with the new built.

[FlashUNC]

Shims are fine for oddball post sizes, or seat tubes not quite to spec.

Just get the right post.

[alancw3]

yes! just bite the bullet and get the correct size.

[oldpotatoe]

Originally Posted by Bencolem

So unfortunately I've had to abandon a bike build that's been months in the planning and am now starting anew with a different frame.

Problem is, the new frame (Parlee Z5) takes a 31.6mm seatpost.

The seatpost I bought for the original build (Enve) is 27.2mm.

What do you think to running a seatpost shim? Thinking a narrower post will be more comfortable but conscious a shim could seize or create unwanted stresses?

Seatpost shims work fine. USE and others make specific seatpost shims..31.6->27.2 very common.

Those differences in diameter on even a carbon SP won't make any difference in 'comfort' that a mere mortal can feel.

Install with carbon paste or antisieze if into a metal frame..check about 1-2 a year.

[jds108]

Shims are fine. My Serotta HSG Ti came with one stock from the factory. I've got shims in a couple of other bikes - no creaks and no slipping. Just grease both sides of the shim before you put it in.

[pdmtong]

Originally Posted by FlashUNC

Shims are fine for oddball post sizes, or seat tubes not quite to spec. Just get the right post.

I shimmed a 27.2 post for my responsorium because I did not want to spend $300 on a WR Composti 30.0. Carbon paste, no issues.

In your case I would get the correct size and dont look back.

[dave thompson]

I'll echo all the positive comments about shims. I've got one on a Spectrum with no issues at all. Use lotsa grease/carbon paste, whatever's appropriate.

[PWong87]

I made a shim out of an aluminum can so that I can use a 27.0 seatpost in a 27.2 seat tube. It works very well but 27.2 to 31.6 seems like a larger jump so not sure how that'll work.

With that said, the shims don't seem to be that expensive so seems to be worth a shot before investing in another seatpost.

[cnighbor1]

I ride three bikes with shims Two worked great Third keep slipping
For CF SP they install the SP with grease that has some grit material in it Use that if shim slips

[hellvetica]

Don't shim an Enve post. I got one from a buddy for cheap, but it had gouges from the shim (Stinner shimgate). So unless you plan on keeping it forever in that frame, pony up and get the right size.