In reply to woodsy:
Heres a route I did back in July
http://connect.garmin.com/activity/200175886
I suspect it's a big longer than you want (48 miles), but if you download the GPX files and then upload it onto
http://www.bikehike.co.uk/mapview.php it might give you some ideas
Given how wet the ground will be, I'd be inclined to go up into Grizedale (possibly via Lawson park but it's a tough climb) and then do the descent from Parkamoor to High Nibthwaite - stunning views and one of the best in the lakes. There's some great, and relatively unknown, riding around Blawith. If you decide to go up to Walna Scar from Stephenson Ground be prepared for a swamp - it was hard work pushing through it back in July. And be careful on the descent back towards Coniston, it's been sanitised so you can go quite fast, but then the drainage ditches catch you and rip your tyre !