Seatpost shim question

[Werehatrack]

What's the favored method for shimming a near-miss seatpost size when a prefab shim isn't
available? I've been handed a suspension post that's 26.0mm, and the bike most needful of such an
adornment wears a
26.4mm post as original equipment. I'm fresh out of .007" sheet shim stock, does anyone have a
suggestion for an alternate, since it appears that commercial seatpost shims this thin are not
among the selections at my most frequent lbs?

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[Werehatrack]

On Sun, 07 Sep 2003 23:48:17 GMT, Werehatrack <[email protected]> may have said:

>What's the favored method for shimming a near-miss seatpost size when a prefab shim isn't
>available? I've been handed a suspension post that's 26.0mm, and the bike most needful of such an
>adornment wears a
>26.4mm post as original equipment. I'm fresh out of .007" sheet shim stock, does anyone have a
> suggestion for an alternate, since it appears that commercial seatpost shims this thin are not
> among the selections at my most frequent lbs?

(perhaps I should point out that I'd really prefer to use a single-thickness shim, and this would
take more than one layer of soda can.)

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[E & V Willson]

I have done this with an aluminum can. Take the ends off and cut the cylindrical side into an
appropriately shaped piece. Two wraps around the seat post should do it.YMMV.

Regards, Ernie

Werehatrack wrote:

> What's the favored method for shimming a near-miss seatpost size when a prefab shim isn't
> available? I've been handed a suspension post that's 26.0mm, and the bike most needful of such an
> adornment wears a
> 26.4mm post as original equipment. I'm fresh out of .007" sheet shim stock, does anyone have a
> suggestion for an alternate, since it appears that commercial seatpost shims this thin are not
> among the selections at my most frequent lbs?
>
> --
> My email address is antispammed; pull WEEDS if replying via e-mail. Yes, I have a killfile. If I
> don't respond to something, it's also possible that I'm busy.

 

[Wannagofast]

Perhaps some scrap rain gutter or flashing. R U near a new home construction site, maybe you find a
scrap of something there?

"E & V Willson" <[email protected]> wrote in message news:[email protected]...
> I have done this with an aluminum can. Take the ends off and cut the cylindrical side into an
> appropriately shaped piece. Two wraps around the seat post should do it.YMMV.
>
> Regards, Ernie
>
>
>
> Werehatrack wrote:
>
> > What's the favored method for shimming a near-miss seatpost size when a prefab shim isn't
> > available? I've been handed a suspension post that's 26.0mm, and the bike most needful of such
> > an adornment wears a
> > 26.4mm post as original equipment. I'm fresh out of .007" sheet shim stock, does anyone have a
> > suggestion for an alternate, since it appears that commercial seatpost shims this thin are
> > not among the selections at my most frequent lbs?
> >
> > --
> > My email address is antispammed; pull WEEDS if replying via e-mail. Yes, I have a killfile. If I
> > don't respond to something, it's also possible that I'm busy.

 

[Kenny Lee]

Werehatrack wrote:
> On Sun, 07 Sep 2003 23:48:17 GMT, Werehatrack <[email protected]> may have said:
>
>
>>What's the favored method for shimming a near-miss seatpost size when a prefab shim isn't
>>available? I've been handed a suspension post that's 26.0mm, and the bike most needful of such an
>>adornment wears a
>>26.4mm post as original equipment. I'm fresh out of .007" sheet shim stock, does anyone have a
>> suggestion for an alternate, since it appears that commercial seatpost shims this thin are not
>> among the selections at my most frequent lbs?
>
>
> (perhaps I should point out that I'd really prefer to use a single-thickness shim, and this would
> take more than one layer of soda can.)
>
> --
> My email address is antispammed; pull WEEDS if replying via e-mail. Yes, I have a killfile. If I
> don't respond to something, it's also possible that I'm busy.
Don't bother with the soda can. I've tried it before. The aluminum shim eventually wears thin like
aluminum foil and you'll find your seat post loosening again after a few rides. They had a thread
about your problem here a few months ago. In that thread a rider from Italy was very persistent in
saying using Mylar as a shim material works very well. Do a Google search and I'm sure you'll find
this thread. As for my seatpost/shim problem, I went to a metalworks shop which specializes in
repairing farm equipment and had the owner make me a shim. It works great and now I don't need to
scour the planet looking for 28mm seatposts but use the more common 27.2.

Kenny Lee

 

[Werehatrack]

On Mon, 08 Sep 2003 01:08:05 GMT, "wannagofast" <[email protected]> may have said:

>Perhaps some scrap rain gutter or flashing. R U near a new home construction site, maybe you find a
>scrap of something there?

All things considered, I'll probably call a bearing supply house in the morning and see if they have
any .007 brass available.

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[Lewis Campbell]

If you really want to get technical, brass is probably not the best material to use for this
application.

Brass with aluminum can have an adverse reaction.

Lewis.

******************************

Werehatrack <[email protected]> wrote in message
news:<[email protected]>...
> On Mon, 08 Sep 2003 01:08:05 GMT, "wannagofast" <[email protected]> may have said:
>
> >Perhaps some scrap rain gutter or flashing. R U near a new home construction site, maybe you find
> >a scrap of something there?
>
> All things considered, I'll probably call a bearing supply house in the morning and see if they
> have any .007 brass available.

 

[Ken Lehner]

Werehatrack <[email protected]> wrote in message
news:<[email protected]>...
> On Sun, 07 Sep 2003 23:48:17 GMT, Werehatrack <[email protected]> may have said:
>
> (perhaps I should point out that I'd really prefer to use a single-thickness shim, and this would
> take more than one layer of soda can.)

I used the entire circumference of a soda can (Pepsi, if it matters) to shim a 26.8 inside a 27.2.
I've had it in for a month, and it hasn't budged.

Ken Lehner

 

[Kenny Lee]

Ken Lehner wrote:
> Werehatrack <[email protected]> wrote in message
> news:<[email protected]>...
>
>>On Sun, 07 Sep 2003 23:48:17 GMT, Werehatrack <[email protected]> may have said:
>>
>>(perhaps I should point out that I'd really prefer to use a single-thickness shim, and this would
>>take more than one layer of soda can.)
>
>
> I used the entire circumference of a soda can (Pepsi, if it matters) to shim a 26.8 inside a 27.2.
> I've had it in for a month, and it hasn't budged.
>
> Ken Lehner
I had to fill a .8mm gap with my "Coke" can shim. Eventually the shim just wore thin and gave way.
As I recall it lasted about five rides or about a week before failure.

Kenny Lee

 

[Werehatrack]

On 8 Sep 2003 03:22:35 -0700, [email protected] (Lewis Campbell) may have said:

>If you really want to get technical, brass is probably not the best material to use for this
>application.
>
>Brass with aluminum can have an adverse reaction.

Hmm. True. Steel might be better, but may be harder to get.

Perhaps I'll try the ultra-low-cost aluminum after all. As Zinn and others say, the advantage is
that they're cheap. I can always swap back to the original post if the shim fails.

--
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[Kw Mui]

Sergio sent me the mylar sheets and am still using them on my MTB for about half year. No slippages
and no water seeping into the seat tube. Also no signs of it wearing thin considering the forces
MTB's are subjected to.

I did try a custom made machined seat shim. It works too, but brass may be required if the shim has
too be thin. However, the gap in the shim will allow water to seep into the seat tube.

Mylar is easier to handle too.

Thanks Sergio, it still works!

Regards, KW Mui

Kenny Lee <[email protected]> wrote in message
> >
> >
In that thread a rider from Italy was very
> persistent in saying using Mylar as a shim material works very well. Do a Google search and I'm
> sure you'll find this thread.
>
> Kenny Lee

 

[Rick Onanian]

On Mon, 08 Sep 2003 01:08:05 GMT, wannagofast <[email protected]> wrote:
> Perhaps some scrap rain gutter or flashing. R U near a new home construction site, maybe you find
> a scrap of something there?

>> > that's 26.0mm, and the bike most needful of such an adornment wears a
>> > 26.4mm post as original equipment. I'm fresh out of .007" sheet shim

Standard rain gutter is .032" or 0.8128 mm...twice as thick as will work. Downspout is thinner, but
corrugated. Most flashing is too thick too.

A piece of standard step flashing ought to be almost perfect at .016" or 0.4064 mm. You might go to
a roofing supply company, or even a roofing installer, and ask for a single piece; they'll probably
give it to you free.

Step flashing is usually 5x7" mill finished Al.

--
Rick Onanian

 

[Werehatrack]

On Mon, 08 Sep 2003 20:04:50 -0400, Rick Onanian <[email protected]> may have said:

>A piece of standard step flashing ought to be almost perfect at .016" or 0.4064 mm. You might go to
>a roofing supply company, or even a roofing installer, and ask for a single piece; they'll probably
>give it to you free.

Umm, no, that's twice the thickness needed; there's 0.4mm difference in diameter, not radius.

Didn't have time to mess with it today; will deal tomorrow.

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[Rick Onanian]

On Tue, 09 Sep 2003 01:51:38 GMT, Werehatrack <[email protected]> wrote:
>> perfect at .016" or 0.4064 mm. You might go to a

> Umm, no, that's twice the thickness needed; there's 0.4mm difference in diameter, not radius.

Of course. That's why I'm in the roofing business, not the bicycle shim business. <BFG>

In that case, there's nothing that I can think of in construction that would be particularly useful.

> Didn't have time to mess with it today; will deal tomorrow.

Good luck!

--
Rick Onanian

 

[Werehatrack]

On Mon, 08 Sep 2003 22:52:10 -0400, Rick Onanian <[email protected]> may have said:

>On Tue, 09 Sep 2003 01:51:38 GMT, Werehatrack <[email protected]> wrote:
>>> perfect at .016" or 0.4064 mm. You might go to a
>
>> Umm, no, that's twice the thickness needed; there's 0.4mm difference in diameter, not radius.
>
>Of course. That's why I'm in the roofing business, not the bicycle shim business. <BFG>
>
>In that case, there's nothing that I can think of in construction that would be
>particularly useful.

Actually, I was hoping someone would know of a common item that was the right thickness; you were on
the right frequency there, just a bit off on the amplitude.

It appears that the coke can trick is going to look like it works for the moment. Time will tell if
there's really a problem.

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