Some marino wool jerseys are super thin and light. I have an old one made by Le Coq Sportif and you can see my bib straps through it but they don't make it anymore. Thinner than any polyester jersey I've had and the best one for hot weather. These look similar:
https://isadore.com/merino-wool-perf...summer-cycling
^^^ That dude's helmet is too small to have a cap underneath
