First of all thanks for BikeCad its great.
I've found a bug where should I report it?
I think the bug was caused by loading up sprockets, selecting 10 sprockets, and then editing and selecting 9 sprockets. The result is a BikeCad file that won't load. You can see this at http://www.bikecad.ca/1326941806865.
If you are able to look at the file you'll around 2947 an entry for "Teeth on Cog 9", which has no value. This causes the free applet to fail with
java.lang.NumberFormatException: empty String
Fortunately I'd saved the file locally so was able to diagnose this
I'm impressed that you were able to deduce that. I wasn't able to reproduce the issue by following the steps that you described, so I'm reassured that others who switch to 10 sprockets and back down to 9 should not have any issues doing so. However, you are correct that the file you reference has an empty field for "Teeth on Cog 9" (which is actually the 10th cog). I still don't know how that could have happened, but I'll continue to investigate the matter.