The Chainlink

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

Most people just use a soda can or a coffee
can,but this build is going to be sold to a customer.Professionalism is at stake here.

Plus after about 5 rides the can shim will start to give and the seatpost will lose its position.

sheet metal from home depot?


Please advise

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Permalink Reply by mike w. on March 25, 2010 at 6:08am
i've used this, HTH:

http://cgi.ebay.com/Problem-Solvers-27-2-to-30-8mm-Bike-Seatpost-Sh...


i believe that various sizes are available.
Permalink Reply by Arrak Thumrs on March 25, 2010 at 7:01am
I'm a little lost here...
Did you ream the ST oversize by .1-.2mm?
Otherwise, why do you have a mismatch so small?

What are the exact sizes you're dealing with? I could make one with a proper collar for you. But really, Thompson makes all the obscurely sized SP's to fit directly if you're dealing with vintage spec's. Kalloy does too on the other end of the price scale http://tinyurl.com/yz2ymlq

Also..
http://tinyurl.com/ybx7xrd
Permalink Reply by Lee Diamond on March 25, 2010 at 8:05am
"Professionalism is at stake here."

Use the proper sized seat post then.
Permalink Reply by Michael A on March 25, 2010 at 10:40am
go see marcus he will have a seat post to fit
Permalink Reply by Doug Haynes on March 25, 2010 at 11:04am
First off if you need to go .2mm just get the right seat post, they make them in all sorts of increments and unless your seat tube has been reamed to the wrong size or has some kind of mechanical damage they make one that fits it.

The problem with trying to ship .1-.2mm is that you are talking about .004-.008 inch which means you need a .002-.004" sheet stock. your average AL can is .002 and you are going to have a hard time finding that thin a stock anywhere other then purchasing shim stock at a machine/industrial supply house.

However, even that is not going to solve your issue. For one the material in the shim is not going to last any longer then the beer can one; it is the thickness, or lack thereof, not the material itself that causes beer can shims to deteriorate. The second, and bigger, issue with a beer can shim is that unlike the commercially available shims dies not have a lip on it so every time you go to adjust the seat post it is going to slip down into the tube or pull out with the post and the only edge to push it down is a supper thin, super sharp edge.

From what I have seen the commercially available shims so not come in a small enough wall thickness to work for you so I am going to repeat what has already been said:

If you are banking your professional rep on this go buy the proper seat post! If there is no size available that fits it you have a larger issue at hand and need to figure out what it is and correct it by either reaming the seat tube, correcting the flaw in the tube, purchasing a seat post to which there is a proper shim made to fit your seat tube or, if there is no hope of a proper fit, scrap the bike or build it and make sure the buyer understands there is something non-standard with their bike.

I will also add this, if you are a pro you should know this; I am but a simple householder with an internet connection and I have a better handle on the issue then you, a cycle factory, do...
Permalink Reply by mfa cycle factory on March 25, 2010 at 11:26am
Sorry if I wasn't clear enough.

Here is the thing.

I measured the ID of my seatpost with a caliper,and the exact measurement came out to 25.5,but there is no such thing as a 25.5 seatpost.....

More than likely the ID of the seat tube expanded by .1 from 25.4.......I was told to get a 25.4,sothat is what I ordered,but it's too small.

I don't have time to order a 25.6 and ream the ID......it will take a least a week for me to get the post....I called some shops in the city
and they have to order it as well


So I'm thinking I. can make a nice shim myself. I have the tools and the ability.However,as stated,coffee cans and pop cans are not the most pro way to go......

can I get some nice,strong sheet metal that comes in millimeters of tenths to solve my
problem?
Permalink Reply by Doug Haynes on March 25, 2010 at 11:35am
How are you going to roll a lip into the shim?

Tin and AL cans are made out of...

Wait for it...

...

SHEET METAL!

You can go buy all the thin AL and steel stock you can find but it is still going to be pretty much the same stuff you are going to be able to go somewhere and buy and you still have the same problem with the lack of a lip on the shim; the beer can shim on my tall bike made me nuts if I ever had to adjust the seat height.

Also 35 gauge steel and AL are both going to be in the area of .006" so you are still not going to be thin enough for what you need. SS only goes down to like 30 gauge which is over a hundredth of an inch. You can get it thinner but no place is going to stock it and a doubt you want a 20 4x8 sheets or a coil of it...

I'm going to go back to what I said before, if you are concerned about this from a professional standpoint you need to do the professional thing. No matter what you make the shim out of a home made shim is not what a professional would do; unless it is what their customer requested or was willing to accept.
Permalink Reply by Ali on March 25, 2010 at 11:49am
Seriously, if you are getting paid to do this, pick up the phone, call the guy and explain to him that you did a knucklehead mistake, apologize, and tell him that it will be a little longer than promised...Part of being a professional is also ability to admit a mistake, accepting it, and then dealing with it...Order the right part get it done right...

-Ali
Permalink Reply by mfa cycle factory on March 25, 2010 at 12:11pm
I've come to a conclusion after weighing several options.

I'm just going to go with a bigger seatpost and ream the tube.

I was even thinking about using metal filler to creste that extra .1 or .2 .......I'm going to try it one day on a junk frame and see how it comes out...

thanx all
Permalink Reply by Michael A on March 25, 2010 at 12:14pm
if a shop decided to ream out my seat tube for a different size post without discussing that option with me first, they would be buying me a new frame
Permalink Reply by mfa cycle factory on March 25, 2010 at 12:27pm
i discuss everything that I do with a customer....I was given complete freedom to correct the seatpost matter...

A problem that occurs often with vintage frames,because the surface Inside of the tube might not be smooth,giving off inaccurate measurements.

I just wanted to weigh every option avaialble
to provide an infinite solution.


again, thank you all.


Michael A said:
if a shop decided to ream out my seat tube for a different size post without discussing that option with me first, they would be buying me a new frame
Permalink Reply by Primitive Don on March 25, 2010 at 12:30pm
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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