27.0 seatpost in 27.2 frame

[Markleo]

When I tight the 27.0 seatpost in the seat tube of my karate monkey that it is supposed to take a 27.2 post, it seems it works. Do you think it should be fine like that or could it make some damage to frame? Thanks

[sean salach]

I would be more worried about damage to the seatpost and the subsequent damage to your family jewels... That's a tiny amount, but still, it's only being held in place by the material above the slot, while there's going to be a little bit of room for movement below that. I would ask the frame building forum.

[ricot83]

Don't do it. I won't work.

[velopax]

I also agree, don't do it, just buy a new seatpost, fortunately 27.2mm is a very common
size you allways find good seatposts on sale anywhere

[locobaylor]

buy
new
seatpost

[cannonballtrail]

There's a shim for converting 27 to 27.2 if you really feel attached to that post. I think fairwheel bikes in Tucson AZ can get them. You can also make a home brew version. As everyone else has said, buying a new post is probably the best bet.

[syl3]

buy
new
seatpost

Said all the people working in bike shops

There's a shim for converting 27 to 27.2

Yes It's called aluminum foil. And another good one is a beer can.

but seriously, who makes a 0.1mm thick shim?

[locobaylor]

Yes It's called aluminum foil. And another good one is a beer can.

but seriously, who makes a 0.1mm thick shim?

27.2
-27.0
0.2mm

math sucks sometimes

[velopax]

27.2
-27.0
0.2mm

math sucks sometimes

Yes genius but when you wrapp this tin foil around the post, it must be 0.1mm thick

[eric_syd]

is around 0.1 mm thick.
Cut it wide enough to just wrap around your seatpost without overlap.
Keep it as long enough to make sure the post does not play at the bottom.
Have done that for a few weeks. Works OK.
Bought a new post for convenience and it was cheap on eBay....

[Manicmtbr]

27.2
-27.0
0.2mm

math sucks sometimes

E-insult Fail!

[thasingletrackmastah]

Make sure the shim goes all the way down, to the end of the seatpost.
But still it's better to buy a new post.

[CaveGiant]

+1 coke can shim

[Whelen97]

Metallic duct tape would work well for this application, and stays where you put it.

[G-Live]

I've used a Guinness shim in the past...

[meltingfeather]

27.2
-27.0
0.2mm

math sucks sometimes

especially when you smugly use it for a complete FAIL!!
the shims go around the whole seatpost. since 27.2mm is the diameter (if you know what that is), the shim fits twice in that measurement.
keep it up. it's entertaining.

[MichaelW]

GO BUY A POST!!!

No I do not work in a shop, I just think ruining a frame and crushing you balls is not a good idea. If you have ever had a post slip and you sat on a nut you would say buy a post too!

[surlyboy]

this is real math 27.0 = 27.2 NO!!!!!!!

[grrrah]

27.2
-27.0
0.2mm

math sucks sometimes

[Boyonabyke]

27.2mm is the diameter. You need thickness of material for the radius. 2x radius = diameter. 8th grade math.

If you don't know that, it would be better for you to use the 27.0, ruin the family jewels, don't get any pi and dont't procreate such stupidity in the gene pool.

[kapusta]

is around 0.1 mm thick.
Cut it wide enough to just wrap around your seatpost without overlap.
Keep it as long enough to make sure the post does not play at the bottom.
Have done that for a few weeks. Works OK.
Bought a new post for convenience and it was cheap on eBay....

I've done this and it has been working on one bike for about two years, now.

Not recommended if you plan on raising and lowering it much, though

EDIT: I should add that this is on a 26" bike. May not work on a 29er.

[apat13]

I've used a Guinness shim in the past...

The Guinness shim is by far the best shim you could make. Puts Coke, Bud Light, and Redbull shims to shame.

Seriously though, you should not ride it just having tightened the hell out of the collar - there will sill be play in the seat tube (kind of like worn bushing on a fork) which will cause the seatpost to gently rock back and forth the whole time you ride (even if you can't feel it). This will introduce extra stress on both the post and frame - specifically stress that they were not designed to handle - which will ultimately lead to either catastrophic failure or premature wear. If you shim it, it is really not ideal and is a hack way to do things, but it will at least be better than just cranking down the bolt. Either plan will probably result in frequent post slippage. The only real way to do this is to get a new post.

[kapusta]

The Guinness shim is by far the best shim you could make. Puts Coke, Bud Light, and Redbull shims to shame.
.

Yes, I just bought a 4 pack of Guinness, and will upgrade from my Diet Coke shim this weekend.

[DriveByBikeShooting]

Said all the people working in bike shops



Yes It's called aluminum foil. And another good one is a beer can.

but seriously, who makes a 0.1mm thick shim?

+1 for using a beer can.

I have and use a 27.0 on a bike that needs 27.2 and my family jewels are just fine

[DriveByBikeShooting]

Yes, I just bought a 4 pack of Guinness, and will upgrade from my Diet Coke shim this weekend.

thats awesome

[logbiter]

keep it up, fun thread!
Seriously, there is no commercial brand of shim that thin. another vote for beer can shim... schlitz, anyone?

[apat13]

I think that bottle is a little thicker than .1mm

[lanpope]

I used a titec ti 27.0 post in my KM and CC for years w/no problem.

Used a beer can shim for a while and then, later on, just wrenched down on the binder bolt.

No problem ever.

YMMV

LP

[CS2]

I used a titec ti 27.0 post in my KM and CC for years w/no problem.

Used a beer can shim for a while and then, later on, just wrenched down on the binder bolt.

No problem ever.

YMMV

LP

After seeing a beautiful Waterford frame with a cracked clamp from someone using a 27.2 instead of a 27.4 I'll never use the wrong one again.

[laffeaux]

If money is tight, use a beer can shim. Or better yet, find a buddy that has a 27.2mm post and trade him your 27.0

If money is not tight buy a 27.2mm post, and then start looking for a new frame that requires the smaller post. Two bikes are better than one.

Don't use the under-sized post without a shim, as you run the risk of cracking your frame. When you tighten it down it seems tight, but when you put 170 pounds on the saddle, and the post is moving 0.2mm inside the frame, bad things will eventually happen.

[stevereeneo]

I think that bottle is a little thicker than .1mm

What bottle... I don't see any bottle in that picture

[hellocook]

most frames are +/- 0.1mm tolerance (!), so let's not have the guys here freak you out about (close to) nothing. first check how much play the post has, maybe you ran into a smaller seat tube ...

next you can use some metal tape or shim (can or alu paper) if needed, both will work just fine.

[barticus]

I think that bottle is a little thicker than .1mm

That's for after the seatpost has suddenly slipped and the stones are crushed. Nothing like a cold one to take down swelling.

[kapusta]

Family jewels crushed? What am I missing? Since when does a seatpost slipping crush your jewels?

[barticus]

When the post suddenly slips all the way down and bottoms out with your full body weight still sitting on it...

[kapusta]

When the post suddenly slips all the way down and bottoms out with your full body weight still sitting on it...

That is not how the post would slip.

[sean salach]

Family jewels crushed? What am I missing? Since when does a seatpost slipping crush your jewels?

I wasn't talking about the seatpost slipping. If it's held in place by only a relatively short clamping area around it, I would think it would be more likely to crimp, or at least have an inordinate amount of stress there. Maybe not though. A crimped seatpost is more likely to break. A broken seatpost can leave a jagged tube of metal pointing up directly at your family jewels. It's a worst case scenario, but If something so simple is going to increase the likelihood of my balls meeting a sharp piece of metal, I'm going to do what I can to avoid it.

[GTR-33]

Steel bike plus undersized seat post equals slippage. My friend had the proper sized seat post for his Fisher Ferrous and it still slipped and needed beer can shim.