My bike's vertical handlebars become very chilly and slippery when it is cold and wet outside.

It needed Sugru! I took it to HackBergen http://hackbergen.no for a fixup..

Step 1: Clean Application Area With Alcohol

Don't know if an alcohol wash was needed, but since I am very generous with the lubricants, there could have been residual oil preventing the Sugru from adhering.

Step 2: Knead Together 2-3 Packs of Sugru

We got by with 3 packs of 5g, but your milage could vary..

Step 3: Use Fingers to Form a Thin Layer

We made oblong Sugru pancakes and pressed them on to a thin layer. After the surface areas were mostly covered, we then used mild soapy water to make it easier to smooth the Sugru out further, while preventing it from sticking to our fingers.