Seatpost Collar size?
 

I'm looking to get a Thomson seatpost collar for my bike, the outside diameter of the seattube is 30.6mm which does not seem to be a size that Thomson offers. Could you recommend a size that would work? It's for a 2010 Kona Major Jake

Why would you not just call/contact the supplier or Thomson?

Salsa - Black or Silver

Edit: 30.6mm= 1.2047244094488 Inches


as per notification below..

kind of weird then .. OP might check their accuracy of measurements ..

seems Bike frame tube diameters are traditionally fractional.. 1", 1.125". 1.25" etc
[French exceptionalism not withstanding]

though the threads and such are usually metric.

No. 30.6 mm = 1.20". 1-1/2" = 38.1 mm. I expect the closest common seat collar size that will work for the OP is 30.0 mm. The next common size up is 1-1/4" = 31.8 mm.

correction noted above.. to past 10th decimal point.. noting its more than 1.200....

Kona is using scandium in the alloy so the tubing sizes are not the same sizes as in 6xxx/7xxx alloys. The only collars I know of in that size are the Salsa Lip-Lock and Flip-Lock.