What size seat clamp/collar do I need?
10-17-11, 04:17 PM
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What size seat clamp/collar do I need?
Hi,
I am trying to find a seat clamp/collar for my old Gary Fisher Montare bike. The seatpost is 27.2mm x 350 mm. What size seat clamp do I need? I would like a quick release one.
Thanks.
David
I am trying to find a seat clamp/collar for my old Gary Fisher Montare bike. The seatpost is 27.2mm x 350 mm. What size seat clamp do I need? I would like a quick release one.
Thanks.
David
10-17-11, 04:37 PM
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The clamp is sized according to the outside diameter of the seat tube. There are 3 standard sizes 28.6mm, 31.8mm, and 34.9mm. Aluminum frames that accept a 27.2mm seatpost will generally use a 31.8mm clamp.
10-17-11, 05:47 PM
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There is also a 30.0 mm clamp and it's used on several bikes, particularly on Surly frames.
10-17-11, 05:50 PM
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With the seat post out, you can measure the OD of the seat tube ..
FWIW, tubes used in most bikes are fractional 1-1/8, 1-1/4, 1-3/8"..
the numbers, 28.6mm, 31.8mm, and 34.9mm are the metric equivalents.
then a manufacturer maybe, shims inside the seat tube ID
to use the common seat post sizes.
FWIW, tubes used in most bikes are fractional 1-1/8, 1-1/4, 1-3/8"..
the numbers, 28.6mm, 31.8mm, and 34.9mm are the metric equivalents.
then a manufacturer maybe, shims inside the seat tube ID
to use the common seat post sizes.
10-17-11, 07:38 PM
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Take a piece of string or strip of paper, wrap it around your seat-tube precisely, take that string and measure its length in mm, then divide by the number pi. That is the seatpost clamp size you need.
