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Old 01-18-14, 09:29 PM   #1
1960frejus 
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Campy Seat Post at 26.

Hi All

In my final shopping for components for my 1963-64 Frejus Pro. My Question has to do with Post Size. I measured the post for the bike in question, and came in at 26.4. Now can I also use a 26.2 post on this Frejus? Thanks for your input, as I am here to learn.

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Old 01-18-14, 10:16 PM   #2
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IF you measured correctly then a post that's .2mm too small will slide in the seat tube and depending on the clamping power maybe stay in place and maybe not cause the clamp to tighten too far.

A post measurement is best taken by using a known diameter post. This way the fit along the complete length of the post can be determined, not just at the top of the tube/lug.

Which clamping style does your Frejus have? The traditional slotted lug with a binder bolt closing the lug around the post or the ahead of the ST and below the TT binder? The traditional with less mass to pull tight usually has an easier time handling a too small post.

Now if the old post is it's self a bit undersized then the amount of the clamping distortion needed to clamp that next size smaller post (and the lug or binder slot closing up is a form of distortion) might be more then ideal. The clamp could go past the spring back point and into the plastic deformation stage. We see the results of a too small post clamped into a frame frequently. Most all the time the reason the bike comes into the shop is because the post won't stay in place, it slips. In trying to both measure and then fit the correct sized post we have to pry out the clamping section of the ST enough to get a sizing post past the top section (the portion of the ST that has been heat affected during the brazing). Then we have to pull the clamp back with the post that fits the ST in place. This is a lot of bending. This is what we want to avoid in the first place by using the correct sized post, and not one a bit small.

Also it's not uncommon to have heat caused warping in the clamp portion of the ST. So sometimes a post will be fitted that slips into a not really round ST. Over time the tube reshapes to more round and the old post becomes the wrong size. Sometimes the amount of tightening that the binder needs to secure this too small post will distort the binder fitting, the lug ears will collapse, the barrel will start to tear off the ST.

So to best answer the question. Use the post that fits the bike best. Andy.
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Old 01-18-14, 10:33 PM   #3
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Type of Frame Seat Post

Thanks Andy...

It was my concern that even though the size was only 2mm smaller that it may or may have made a difference, and now understand and see that it does, as I do not want a post slipping down. I have up loaded a picture of the type frame post I have to fit the seat post. thanks... you helped so much in one thing you said... Fit the same size the Bike calls for... and fit the 26.4 it's asking for. One more question... Did Campagnolo make a nuovo record seat post sized 26.2?

Philo

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Originally Posted by Andrew R Stewart View Post
IF you measured correctly then a post that's .2mm too small will slide in the seat tube and depending on the clamping power maybe stay in place and maybe not cause the clamp to tighten too far.

A post measurement is best taken by using a known diameter post. This way the fit along the complete length of the post can be determined, not just at the top of the tube/lug.

Which clamping style does your Frejus have? The traditional slotted lug with a binder bolt closing the lug around the post or the ahead of the ST and below the TT binder? The traditional with less mass to pull tight usually has an easier time handling a too small post.

Now if the old post is it's self a bit undersized then the amount of the clamping distortion needed to clamp that next size smaller post (and the lug or binder slot closing up is a form of distortion) might be more then ideal. The clamp could go past the spring back point and into the plastic deformation stage. We see the results of a too small post clamped into a frame frequently. Most all the time the reason the bike comes into the shop is because the post won't stay in place, it slips. In trying to both measure and then fit the correct sized post we have to pry out the clamping section of the ST enough to get a sizing post past the top section (the portion of the ST that has been heat affected during the brazing). Then we have to pull the clamp back with the post that fits the ST in place. This is a lot of bending. This is what we want to avoid in the first place by using the correct sized post, and not one a bit small.

Also it's not uncommon to have heat caused warping in the clamp portion of the ST. So sometimes a post will be fitted that slips into a not really round ST. Over time the tube reshapes to more round and the old post becomes the wrong size. Sometimes the amount of tightening that the binder needs to secure this too small post will distort the binder fitting, the lug ears will collapse, the barrel will start to tear off the ST.

So to best answer the question. Use the post that fits the bike best. Andy.
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Old 01-18-14, 10:40 PM   #4
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I suspect that you measured wrong. IME Frejus never had posts that small in that era. I suspect that the right post is 26.8.
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Old 01-18-14, 10:59 PM   #5
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There's a post on EB for a campy nuovo record at 26.2 and as a one who owned and owns 4 frejus models, have never seen that size for a nuovo record post, so the seller must have measured incorrectly. Thanks...

Philo

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I suspect that you measured wrong. IME Frejus never had posts that small in that era. I suspect that the right post is 26.8.
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Old 01-18-14, 11:09 PM   #6
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Quote:
Originally Posted by 1960frejus View Post
There's a post on EB for a campy nuovo record at 26.2 and as a one who owned and owns 4 frejus models, have never seen that size for a nuovo record post, so the seller must have measured incorrectly. Thanks...

Philo
Campagnolo made 26.2 posts for Vitus aluminum frames, but Frejus steel frames should take a larger post.
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Old 01-19-14, 07:47 AM   #7
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FWIW, Philo, my 63 Frejus Professional takes a 27 mm seat post. How did you measure the seat tube? It is important to measure well below the seat cluster clamp "ears", as they could have been deformed in the past. Machinist tools are handy for this.
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Old 01-19-14, 08:43 AM   #8
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At least according to Sutherland's, second edition, "quality double butted tubing" for Italian bikes would be either 26.8, 27.0 or 27.2 seat post. French bikes would call for 26.4 or 26.6.
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Old 01-19-14, 10:45 AM   #9
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One post in 25.0 and shims out to the frame ID can be trial and error , with out major expense.

1" , 25.4mm is also a common post OD served by a variety of seat post shims (various distributors).

so guessing is cheaper.. if not spot on than whole seat posts (other than Kalloy)


Have Campag SR 25,0 left from my AlAn. frame .. 80s ..

Fwiw, straight gage frame tubes of less premium steel will be thicker walled,
so post, following tube ID, will be smaller..

Last edited by fietsbob; 01-19-14 at 10:51 AM.
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Old 01-19-14, 09:28 PM   #10
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Quote:
Originally Posted by rootboy View Post
FWIW, Philo, my 63 Frejus Professional takes a 27 mm seat post. How did you measure the seat tube? It is important to measure well below the seat cluster clamp "ears", as they could have been deformed in the past. Machinist tools are handy for this.
Lacking said tools, you could look at the slot and see if it's parallel; if it's pinched together you can usually prise it open with a flat screwdriver pretty easily. Into the slot from above, maybe with a rag over it for the paint, and once it wedges in you just gently lever it side to side.

This will only work nicely in most cases, when the clamp hasn't been radically crushed onto a much too small post... 27mm down to 26.2mm would be starting to get a little dramatic.
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Old 01-20-14, 08:19 AM   #11
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These can be a very handy tool for measuring the ID of a tube, if you know how to use them properly. I didn't until recently, and I've had a set of these for years. Does require a transfer to either a caliper or micrometer though. Which not everyone has. These can be found very cheap on ebay.
http://www.starrett.com/metrology/pr...ing-Gages/229B

http://www.ebay.com/itm/Brown-Sharpe...-/111261101773
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