.1 or .2 of a millimeter shim for a seatpost

Replies to This Discussion

Permalink Reply by mfa cycle factory on March 25, 2010 at 12:42pm

ah,man,thanks for this info .....I'm going to check them out......

I just detest unexpected issues are the wrong time.....frame is good to go and looking sweet....I get ready to put the seatpost in,and then bam!....not so fast buddy....I call those issues bicycle radicals...unseen spirits that come out of nowhere to make the smallest thing the most difficult.....like putting on the top part of a tire....."just get in there already!"

: )
lol

Primitive Don said:

I've had this exact issue, but have not been able to solve it yet. J&B sells a 25.6 seatpost, most likely the Kalloy one referenced above, but they were out of stock last time I checked, along with most online vendors. I'd assumed incorrectly that my seat tube was a 25.4, but like yours mine is just a hair too loose. Let us know what you end up doing.

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Permalink Reply by Arrak Thumrs on March 25, 2010 at 1:40pm

Just one last thought on this:

You could ream to fit an off-the-shelf 25.6 and use a shim if the rider prefers to not buy another post. Then, if the rider doesn't like it, the answer is a no-brainer. That's probably the fastest end to your problem. The shim would probably work better too, since it would be twice as thick (remember, we're still talking very thin here).

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Permalink Reply by Lee Diamond on March 25, 2010 at 3:54pm

Yeah. That stops some people.

I am obviously not one of them.



M.A.R.K. said:

That's what I was gonna say, but didn't want to sound like a dick.

Lee Diamond said:

"Professionalism is at stake here."

Use the proper sized seat post then.

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Permalink Reply by mfa cycle factory on March 25, 2010 at 4:05pm

but there is no proper seat size when the tube has been modified due to wear or the surface is not smooth.

which was the point of the post

in those situations, some type of fix will need to be applied in the form of manipulation(shim,reaming,etc)

Lee Diamond said:

Yeah. That stops some people. I am obviously not one of them.



M.A.R.K. said:

That's what I was gonna say, but didn't want to sound like a dick.

Lee Diamond said:

"Professionalism is at stake here."

Use the proper sized seat post then.

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Permalink Reply by Michael Perz on March 25, 2010 at 4:38pm

If your seat tube is so worn that it can't compensate for a 0.1mm difference in post diameter, then you've got a problem that no shim will solve. Sounds to me as though someone at one point tried to force a seat post that was too large into the frame and damaged the seat tube (and lug, if applicable). Also, if the surface is "not smooth" enough to safely clamp the correct size post then you may want to reconsider selling that frame to someone if reputation is a concern.

mfa cycle factory said:

but there is no proper seat size when the tube has been modified due to wear or the surface is not smooth.

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Permalink Reply by mfa cycle factory on March 25, 2010 at 5:00pm

thanks for the feedback

However, I spoke to some reputable sources, and the seat tube is salvageable....where just talking tenths here...not full millimeters.

thanks again.

Michael Perz said:

If your seat tube is so worn that it can't compensate for a 0.1mm difference in post diameter, then you've got a problem that no shim will solve. Sounds to me as though someone at one point tried to force a seat post that was too large into the frame and damaged the seat tube (and lug, if applicable). Also, if the surface is "not smooth" enough to safely clamp the correct size post then you may want to reconsider selling that frame to someone if reputation is a concern. mfa cycle factory said:

but there is no proper seat size when the tube has been modified due to wear or the surface is not smooth.

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Permalink Reply by Bikefreeek on March 25, 2010 at 10:20pm

I sometimes use a piece of offset printing plate for a shim. Ask a local printer (needs to be an offset printer not copier like Kinkos) if they have any old used plates they'd be willing to offer. They're aluminum and a thicker gage than beer cans.

To avoid the problem of the shim slipping into the frame, just bend the two corners diagonally into small triangles (2-3mm) that will stick out from the top of the seat tube at the split where the collar clamp is.

Before shimming or reaming I would flex-hone it and see if that is enough to even it out for a normal seat post. But not everyone has a flex-hone.

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