Is there any way to change the font on your website? At first glance, the homepage (to me) looks like one of those "placeholder" pages you find when a domain name has been parked but no website built. I think changing the font or color scheme may help the website draw more people in right away.

Have you tried facebook? Twitter? Getting your ride listed on cycling event websites, etc? Asking local cycling groups to add it to their calendars? Asking local bike shops (and not-so-local, if there aren't that many metric rides in your area) to add it to their calendars or provide flyers to customers?

One thing that does rub me the wrong way, on your homepage, is the quote "If you need materials for everyone to ponder while the peas are cooking, contact any of the beneficiary groups and request a copy of their latest news release or annual report" in the suggested ways to raise money. You really should provide downloadable materials (flyers, etc) for your participants to hand out and hang up. You don't have any printing cost, just the cost of creating the PDF and posting it on the website.

You may also want to change "about us" to "about our cause," so people can learn about the beneficiaries of the ride and the person who inspired it more directly. I think the inspiration/beneficiaries may also belong on the homepage as well.

Also, guilting your current participants by pointing out that it costs a lot to hold the ride and no one brings in donations? That's not very encouraging for people. Positive reinforcement, such as posting the total amount raised for the last four years, posting a hopeful "goal" for this year, recognizing your biggest fundraisers, would be a lot more effective than saying "hey, none of our riders meet this goal. Go bring us more money!"

I think the website looks pretty good otherwise, and that you have some good content and guidance for potential riders. If you change your presented attitude from "meh, this is expensive and we know you can do better" to "you did GREAT, let's top it this year!" would probably go over better with your riders.