Use the latest version of Circos and read Circos best practices—these list recent important changes and identify sources of common problems.

If you are having trouble, post your issue to the Circos Google Group and include all files and detailed error logs. Please do not email me directly unless it is urgent—you are much more likely to receive a timely reply from the group.

Don't know what question to ask? Read Points of View: Visualizing Biological Data by Bang Wong, myself and invited authors from the Points of View series.

5 — Tick Marks, Grids and Labels

9. Tick Rings

A tick set can be automatically drawn at multiple radial positions if you define more than one radius for the set. 

<tick>
# drawn at one radius
radius = dims(ideogram,radius_outer)
...
</tick>

<tick>
# drawn at two radii
radius = dims(ideogram,radius_outer)
radius = 0.8r
...
</tick>

<tick>
# drawn at three radii
radius = dims(ideogram,radius_outer)
radius = 0.8r
radius = 0.6r
...
</tick>

Tick rings are useful when your image has many tracks and you'd like to have multiple instances of tick marks.