"Do your best to present yourself to God as one approved, a worker who has no need to be ashamed, rightly handling the word of truth."

It's better if you are able to engage with people in sharing the Gospel, but Bible tracts are a perfect resource to give to riders if you don't have time to finish a presentation.  They're also an ideal hand out even when you do. Here are a few of my favorites.

Ray Comfort and his crew over at Living Waters make some of the best

and most memorable tracts we've found. Easy to read, biblically accurate

and often times humorous. They're also inexpensive to hand out so don't hesitate to give them to your riders.

Million Dollar Bill

10 Commandment Coins

Million Dollar Gospel of John

Great resource to use as a concordance to look up verses in different translations.

BlueLetterBible.org

Understand the Bible with 10-minute audio guides for every chapter.  Check out ThroughtheWord.org for more information.