In the interest of safety and comfort I subjected myself to the last two days of commuting during peak heat times- 3-11P so that I can test a theory that relates to this thread.
Bike- 2006 BMW R1200RT, windshield highest position.
Wed-Temp to work, rte 495-100degrees! I wore Astars textile suit similar to this one but an older discontinued model with no venting-
http://stores.sportbiketrackgear.com/Detail.bok?no=2819. Underneath I wore a long sleeve Pantagonia breathable lightweight base layer shirt, and Heavy cotton shorts. Of course riding boots and excellent Lee Parks deerskin summer gloves.
Thurs- Temp, 99 degrees. I wore a Firstgear Mesh jacket, Klim lightweight (I think they are actually for dirt riding) overpants with some venting in the thighs and crotch area, light armour. Nike Drytech (or whatever they call it) T shirt. Same shirts and gloves.
Results: I defineatly felt hotter today (Thurs) while riding. Toward the end of the ride I could really feel myself starting to sweat and feel really uncomfortable. I couldn't wait to get some water and get into the AC!!
Yesterday I was hot (hell it's hot out!!!) but the fact that the hot air wasn't getting to my core helped to keep me more comfortable.
I've always read that the professionals keep their skin covered when riding in temps HIGHER than their body temp, some even swear by leather even when it's super hot!! And by trying this little experiment, I've realised that they are correct. If the outside air temp is higher than your body temp it only makes sense that that air is going to raise your temp. If the air is slightly cooler (but I would guess that it would be best to be at least 10 degrees cooler) than yes vented/mesh gear would def. help to keep one cooler. I know that when I wear the mesh jacket in temps below 80 I really feel the cooling effects.
So, what have I learned? Well the dudes going the other way in tank tops and shorts were doing nothing constructive in trying to keep cooler (I won't even get into the safety part here)..........If you want to keep your core temp at it's absolute minimum---keep the HOT air off of it!
I've got all kinds of gear (I'm a gear junkie) so I might as well use it!
The biggest PITA of dressing this way when its 100 degrees---answering the same old "Hell, ain't you hot in all that shit?" when I get to work.
Oh well, live and learn.
Carry on......