Where I live, little bloodsuckers really come out in full force during monsoon season, doesn't make for pleasent mountain biking. Plus, there'd be like 10 people in my group and they will all come bite ME.

I find that repellents sold in stores aren't all that effective for me, and they smell toxic. There's a citronella repellent I used to buy in Thailand that's dead effective. In the absence of that, I use lavender oil, sometimes neat, sometimes diluted with some carrier oil. It has the added advantage of being able to treat bites from mosquitoes that refuse to be repelled. And it smells much better.