This wiki is a real-world reference to help PHers decide which size jersey is going to be best for them.

Member (optional)	Height	Weight	Jersey	Size	Comments
Gruffy	6'4"	80kg	Regular	L	Fits closely all over but isn't race-tight
Gruffy	6'4"	80kg	Pro-cut	7	Fits well around chest, little loose around mid-section, bicep and neck but not enough to want to go down to a 6
Steve vRS	5'10.5"	77kg	Regular	L	Comfortably loose
Steve vRS	5'10.5"	77kg	Regular	M	'Race fit' - a challenge for the zip!
hora	6'2"	96kg	Regular	XL	Felt like I'd been poured into it. But a little bit more and it'd be spot on. So I'd go for a XXL with hindsight/next time
Kell	5'11"	100kg	Regular	XXXL	A little baggy in most places bar my fat stomach and my amazing guns - I wouldn't have wanted one any smaller
Bigdom	6'5"	115kg	Regular	XXXL	Comfortable, a size down would be pretty tight
Bigdom	6'5"	115kg	Pro-cut	11	Comfortable, a size down would be pretty tight, fits better than regular
Jesusbuiltmycar	5'10"	70kg	Regular	M	Uncomfortable, Race Tight
WarrenG	5'10.5"	77kg	Regular	XL	Almost Roadie-fit. Was better at 85kg in the past!?
WarrenG	5'10.5"	77kg	Pro-cut	8	Not quite Roadie-fit, fits in the middle, but neck and arms are slack - need to Lift.
ajk	6'1"	90kg	Pro-cut	8	A little loose generally and quite loose around arms & neck, would defo drop down a size next time