well trial and error is the way to go. i have found so far the best method for keeping warm on and off the bike.assos short sleeve base layer next to skin on top of that merino long sleeve base layer then cycling jersey and last my waterproof cycling jacket ,none of these items are bulky (im the bulky one) so far they work im not cold when i stop..as i said the big problem i had was when i stopped i found the merino base layer very cold next to skin .i just bought a nice helly hanson long sleeve base layer this morning from chainreaction cycles looks great hope it does what it supposed to do.