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Old 09-16-10, 01:56 PM   #1
youngdoc
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32.6 mm seatpost clamp

I just finished a major rebuild on an older frame and the one part I cannot seem to get my hands on is a 32.6 mm seatpost clamp. I have performed hours of searching the net, to no avail. I spotted an older thread in this forum (with a less-specific subject line) in which the OP was facing the the same dilemma and unfortunately the suggestions there were no longer valid.

Can anyone help me find this part?

Many thanks in advance.
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Old 09-16-10, 02:24 PM   #2
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32.6 mm sound suspiciously like the diameter of the seatpost itself. The seatpost clamp must go around the frame's seattube, not the seatpost so it has to be a bit larger. Seatpost clamps typically come in 28.6 mm (1-1/8"), 30 mm, 31.8 mm (1-1/4") and 34.9 mm(1-3/8"). Measure your seattube's outside diameter and see if it matches one of these sizes.
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Old 09-16-10, 02:43 PM   #3
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Quote:
Originally Posted by HillRider View Post
32.6 mm sound suspiciously like the diameter of the seatpost itself. The seatpost clamp must go around the frame's seattube, not the seatpost so it has to be a bit larger. Seatpost clamps typically come in 28.6 mm (1-1/8"), 30 mm, 31.8 mm (1-1/4") and 34.9 mm(1-3/8"). Measure your seattube's outside diameter and see if it matches one of these sizes.
I think there was a typo here, the 1-1/4 size is usually rounded to 32mm or 31.8. If you have a 31.6mm seatpost you don't need to measure. The seat tube diameter has to be larger, so it's surely 1-3/8" (34.9 or 35mm). Note metric sizes vary because bicycle tube ODs are in imperial sizes, and the metric variation is the result of rounding differently.
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Old 09-16-10, 02:53 PM   #4
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Originally Posted by FBinNY View Post
I think there was a typo here, the 1-1/4 size is usually rounded to 32mm or 31.8. If you have a 31.6mm seatpost you don't need to measure. The seat tube diameter has to be larger, so it's surely 1-3/8" (34.9 or 35mm). Note metric sizes vary because bicycle tube ODs are in imperial sizes, and the metric variation is the result of rounding differently.
I also thought it might be a typo as 31.6 mm seatposts have become a new standard these days. However, seatposts being what they are, almost any size is possible.

I was sure it wasn't the size seatpost clamp diameter that the OP needed and 34.9/35 mm is almost certainly the right one.
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Old 09-16-10, 04:06 PM   #5
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http://www.bikeparts.com/productsear...yName=SEATPOST CLAMPS
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Old 09-17-10, 10:36 AM   #6
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OP here. 32.6 is what the mechanic (who is rebuilding my bike) told me. In any event, I have asked him to re-measure the exterior seat tube diameter with a caliper based upon the above comments. The frame is an aluminum 1996 Trek 8000, so who knows, it could be an odd size. I'm pretty sure that 32.6mm seat post collars do/did exist. If it helps, I do know that this is the seat post that I just purchased for it, and this post does fit my seat tube:

Thomson Masterpiece 330mm Seatpost
Item #: 50-2616-BLK-272

https://www.performancebike.com/weba...mmaryOnly=true
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Old 09-17-10, 10:40 AM   #7
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Trek made the bike see if they have the replacement parts , ask via Trek dealer or Trek corp site.
all else fails , get a larger one and shim for the differences.
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Old 09-17-10, 11:18 AM   #8
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For all practical purposes there are no odd sizes, though paint or powder coat could bring up a 1-1/4 to slightly over the nominal. You need a 1-1/4" collar or 32mm, or whatever they rounded it to. It's split and will accommodate the thick paint.
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Old 01-17-15, 04:30 PM   #9
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Also looking for an alternative 32.6mm clamp to the Specialized one for my carbon sirrus.


32.6 mm clearly marked


Went for a ride a couple of weeks ago without any drama. Went into the garage yesterday to give the bike a bit of lube and noticed the seatpost clamp in two pieces. It had sheared while parked up.

Have got a replacement specialized one but seems there are a few other people who have experienced similar problems. The clamp had been torqued up, just a rubbish bit of kit.
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File Type: jpg Clamp (2).jpg (88.2 KB, 39 views)
File Type: jpg IMG_5495.jpg (98.2 KB, 39 views)

Last edited by Ajh800; 01-18-15 at 05:04 AM.
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Old 01-17-15, 05:00 PM   #10
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After France fell back in with the Pack, Tube OD have settled on Inch -fractional so 1.250" not 32.6 mm = 1.28346456693 in..

Actually 1.250 in = 31.75 mm ( so 32 mm)


To not apply too much force, I doubled up clamp bands, adding 1 directly around the seat post Itself, On Top of the one that causes the frame to squeeze around the post .

Using a 27.2 Post I Got one of these : WC Seat Post, Size 27.2mm, Aluminum, Black ? WiseCracker ..



I first used a Regular QR band clamp and did similar with my Brompton Seat Post .
so to fold the bike and slip the post Down, I open 2 QRs stacked on top of each Other..
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Old 01-18-15, 04:53 AM   #11
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I was initially tempted to try a 31.9mm thinking it would be near enough - did a quick Google then phoned Specialized shop and all advice is I need a 32.6mm - no 'near enough' tolerance for carbon frames.

Have seen this but retails at 40+ euros inc delivery which is a bit steep.


X-Clamp 3 32.6

I know lots of Specialized owners have had 32.8mm clamp issues so if anyone can recommend a sensibly priced alternative it would be a great help.
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Old 01-18-15, 10:43 AM   #12
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Ah Hidden data, finally Outed.. Its a Carbon Frame , not one made of standard sized tubes at all ..

They removed Metal for those slots to make it as light as possible because they Knew their customers weigh every Part ..


have Specializes send a bag of a dozen since the replacements will look the same . put a new one on every couple weeks.

Last edited by fietsbob; 01-18-15 at 10:46 AM.
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