You are going to have so much fun at your clinic. I just did one at Rutgers and had a blast. It's hard as Hell, but well worth it. I intended on taking my (new) Masi CXSS, but it ended up taking my 25YO "Vintage" Peugeot MTB. I strapped on skinny tires, and went for it. Although heavier than I wanted, it did great. It also ended up being an ice breaker when people started asking where my rear brake was. (CS mounted U-brake).

There were all types of bikes represented there from fully suspended MTB, to high end CX. There was even a couple doing the clinic with a tandem. I know I'm excited to start the season no matter what bike I end up riding.

Don't worry about your fitness. It'll come. Again all levels of fitness were represented and it didn't matter. They broke us into groups on the second day for those who wanted a slower pace or wanted more work on skills and for those who wanted more race pace experience. At the end we rejoined and did the course three times to get practical experience on the skills we learned.

Enjoy your clinic, now get out and ride!