Which crankset?

Barrzy257

Im weighing up my options for power meters, I've had a look at the power2max which looks interesting but I'm insure of which model to go for if I do pick this route, But I'm usure of which ones would fit my bike? I have a ribble sportive bianco, I think it's bsa68 unless someone can tell me different? And I currently run a sram gxp bb
Any help much appreciated!!