I need to place a team order (Castelli), and want to buy arm and knee warmers. However, I’m undecided on size - medium or small.
I wear size medium clothing in Castelli for their race fit items. I’m 6’ (183cm) and 150 lbs (68kg). Castelli says I should order size medium warmers. I bicep is 31 cm and my thigh is 47cm in circumference. I currently have a mix of size small and medium arm and knee warmers (from other brands).
Size small or medium?
Michael
I find Castelli sizing to be accurate on the chart.
I just got some Castelli leg warmers (haven’t replaced my arm warmers yet). Their sizing chart refers to both short/bib size and weight. Using that, I got 2 different sizes. I went with the weight based size (which was bigger) and they fit fine. My previous warmers were Pearl Izumi and the Castellis are definitely run a bit smaller than those.
FWIW, I’ve bought a bunch of Castelli team kit over the past 2 years since my club switched and while Castelli definitely runs a little bit smaller/tighter than some other brands, I have found their sizing charts to be accurate as long as you are honest with yourself 
i’m about the same height and weight as you, don’t know thigh and bicep dimensions and think measuring specifics are too variable to bother.
fwiw i wear small castelli race clothing but medium arms and knees. based on that, i’d say if you wear medium castelli generally then medium warmers would be the go but ymmv
Thank you. I ordered medium arm and knee warmers.
Michael