What should I look for in a cycling undershirt for warm weather? Road season is about to start here and I think that it is time I stopped using my cotton singlets as an undershirt and start using something more specific for cycling (and racing in particular).  What is the best material for me to get?
My favourite base layers are Merino wool, in particular from Rapha. They are seriously not cheap, but they are definitely worth it. Very warm in winter with the long sleeve, but surprisingly cooling in the summer with the short/no sleeve.