don't know how much i can help..but i would never really "trust" a wheel of a stranger. you can still keep a reasonable distance and get a benefit of a draft. you should be able to judge some of the riders abilities fairly quick. if a rider brakes in front of you, you always have room to roll up along side them while preparing for them to possibly move over on you. i guess it just takes practice in those situations. don't force yourself into something you are not comfortable with though.