I take a shower right in the parking lot right after each ride. It cools you off and washes off the tick and chiggers. You can also just fill some empty soda bottles with water and rinse your arms and legs. If you get the ticks and chiggers off right away they will not cause problems.
Hmmm... that looks familiar...just like the bites on my leg! Mercer has those critters as well. 1000 times worse than ticks because you can't see'm until they have already had their meal and left. They don't suck blood. Their saliva dissolves skin which they then eat and the saliva is what causes the histamine reaction!
Beware....If you have been exposed, they will remain in your clothing, shoes & socks too! Freaking bites take forever to heal. I'll take ticks any day.