Bicycle Mechanics - 27.2 seat post, will a 28.6 clamp work?

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DavidLee
06-09-06, 07:16 PM
Hey guys, sorry for so simple a question. :o I have a 27.2 mm seat post with a QR clamp & want to get a bolt style clamp. I cannot find a 27.2 clamp anywhere. Am I looking for the wrong size clamp, are clamps supposed to be sized larger than the seat post? Should I just be looking for a 28.6 mm clamp which seems to be everywhere? Again, sorry for the simple question but I'm lost on this one.

Thanks all.

mattface
06-09-06, 07:22 PM
I don't know the answer, but I'm going to guess.

the seatpost is 27.2 typical seat tube walls are .7 mm thick. seatpost diameter+ (seat tube thickness x 2) = 28.6

Like I said I don't know, but this seems a logical deduction.
Retro Grouch
06-09-06, 07:45 PM
Hey guys, sorry for so simple a question. :o I have a 27.2 mm seat post with a QR clamp & want to get a bolt style clamp. I cannot find a 27.2 clamp anywhere. Am I looking for the wrong size clamp, are clamps supposed to be sized larger than the seat post? Should I just be looking for a 28.6 mm clamp which seems to be everywhere? Again, sorry for the simple question but I'm lost on this one.

Thanks all.

Sometimes one measurement is worth a thousand guesses.

Wrap a piece of paper around your seat tube where the clamp goes. Mark where the paper overlaps. Measure that distance carefully with a millimeter ruler. Divide by 3.14. Buy that size clamp.

Old_Fart
06-09-06, 08:18 PM
I have two bikes that have 27.2 seatposts and they have different clamp sizes.
Only way to be sure is to measure it.
TRUMPHENT
06-09-06, 09:10 PM
Go below. All you need really is a nut. Not a cashew!


http://www.nashbar.com/profile.cfm?category=117&subcategory=1189&brand=&sku=8446&storetype=&estoreid=&pagename=
Grand Bois
06-10-06, 07:34 AM
Go below. All you need really is a nut. Not a cashew!


http://www.nashbar.com/profile.cfm?category=117&subcategory=1189&brand=&sku=8446&storetype=&estoreid=&pagename=

That's a nut and bolt, not a clamp.
The Great Stonk
06-10-06, 11:32 AM
what frame are you using ? seat post size doesnt matter, its the external diameter of the seat tube you need to know.

if its a steal frame it will probably be a 28.6 clamp since steel tubes have thinner walls, if its an alloy frame it could be anything, reer to the manufacturers website.