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Seat Post Diameter

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Old 10-25-16 | 02:21 PM
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Seat Post Diameter

I've got an older model Cannondale CAAD 8 frame that I'm trying to build. I need a seat post and was measuring the inside diameter of the seat tube, but my calipers are screwing up on me, giving one measurement one time and another the next. I'm pretty sure it is either a 27mm or 27.2mm but I need to be sure.
Does anyone have one like this Cannondale and can tell me for sure? Thanks
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Old 10-25-16 | 02:30 PM
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Bikes: Catrike 559 I own some others but they don't get ridden very much.

27.2 mm is a pretty common size. See if you can borrow one that size to test fit.
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Old 10-25-16 | 02:35 PM
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Bikes: Ritchey Swiss Cross | Teesdale Kona Hot | Haro Extreme | Specialized Stumpjumper Comp | Cannondale F1000 | Shogun 1000 | Cannondale M500 | Norco Charger | Marin Muirwoods 29er | Shogun Kaze | Breezer Lightning

Cannondale has traditionally used 27.2

27.0 would be something I would expect on a steel frame also
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Old 10-25-16 | 02:54 PM
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Measure OD, and tube wall thickness with your caliper .. OD Minus 2x the tube wall thickness should leave you the ID.
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