We have various routes around the area we can recommend so just let us know the length and type of cycle you would like to do.
Here are a few links to websites that may be of interest to you while planning your stay:
Paths and trails around Fort Augustus - https://www.moragslodge.com/media/269097/paths-around-fort-augustus.pdf
Forestry trails in the Great Glen - https://forestryandland.gov.scot/images/pdf/rec_pdfs/great-glen-leaflet.pdf
Great Glen Way - http://www.greatglenway.org/
Enjoy Loch Ness - http://enjoylochness.com/
South Loch Ness - https://www.visitinvernesslochness.com/
Orbea Bikes - https://www.orbea.com/gb-en/