The Garburn Pass mountain bike route can be found in the East Lake District. It is graded Hard / Difficult and is 22 miles long. It kicks off in Waterhead (at the car park near the Regent Hotel on the edge of Windermere) just outside Ambleside, on the shore of lake Windermere. This mountain bike route heads east to Kentmere and back. It's not an easy ride with just over 4100ft of climbing in 22 miles. There are plenty of steep climbs, the biggest being the climb out of Kentmere to the top of the Garburn Pass. This is definitely a climbers route, but one with plenty of great descents.
GPS log courtesy of Flattyres-MTB. A full route guide for this ride is available on their website here: The Garburn Pass