Depends on how cold it is where you're riding.... Nobody can make that decision but you.
I know here in the Rockies when it's gonna be below the 40's, my ass has some sort of base layer on. I just have multiple layers and add some when it's gonna be cold out. It's easier to take some stuff off then it is to not bring enough with you and freeze your ass off.
"When I do good, I feel good; when I do bad, I feel bad. Thatís my religion." - Abraham Lincoln
Originally Posted by sedition
Moral of the story: If your going to rob people, wear a diaper.
Milo pretty much nailed it. Assuming you're cold, the base layer is very important. It needs to be either poly or wool...no cotton. They are breathable and wick moisture away from your skin. I like Patagonia's wool and capilene bases and I move to more wool every year. The bottom layer should be very thin. If it's cold, then add a thicker next layer and so on. Then you can strip off layers as the temperature rises.
I get chilly easily (I wear a fleece year round in the office at work), but moderate heat and humidity don't make me uncomfortable.
No matter what the temp on the mountain is, I always rock the 3 layer system. UA coldgear base, fleece mid, 15k or 20k shell. There are some days that my wrist gaiters are more wet from sweat than snow.
I'd rather be warm and moist than cold and clammy, that's for sure!
yep this is all a matter of preference thing.. see how tarzan above is bundled like the damn michelin man but im the opposite .. im extremely warm natured .. my kit has nothing over 10k in it and normally I rock a 5k jacket and 5 or 8k pants .. the 10ks only come out in the most severe cold...
as someone posted earlier if you are cold then yes upgrade to a good moisture wicking base layer . if you are warm now then roll with it