I wear a Gore Tool Jacket Medium below 45...
I wear a Gore Tool Jacket Medium below 45 deg with a light Craft baselayer - below 30 deg I use a heavy Craft baselayer - I love the Tool jacket, fit etc... which Gore jacket would be good in the 40's and 50's? Is the fit like the Tool?
For a jacket that fits like the Tool, but is a little lighter weight, I'd go with the Countdown SO Jacket. Very similar fit, just a little lighter, but still full WINDSTOPPER, so you get very similar protection.
hope that helps,
Robert, Gore Bike Wear