Carry a plastic bag full of paper towels in your bike bag!

In the past year or so I've given paper towels out to 4 or 5 people who I spotted by the side of the road with grease on their fingers and a panicked or despondent look on their face. Even if they had already managed to get their chain back on, they still had to deal with thick black grease on their hands.

I've rarely seen such profuse gratitude as when I handed these people the paper towels.

#BikeTooter

@timmc Always helps to have something made of oil to help as well. That can be peanut butter, sunblock, chapstick, or whatever moisturiser you have to hand. It'll get way more oil off than any detergent.
@spacehobo Interesting thought. I always advise people on how to get the remaining oil off when they get home (cooking oil, then soap) but I hadn't considered bringing some with me.
@timmc
I've had great results with just chapstick and sand in the field!