Seems like rear ABS on a bike that sees gravel is a bad idea. I agree that disabling the system seems best. My experience with my old (2004) BMW coincides with Alex's: they were crude systems at best. While I'm sure newer ABS is far superior and capable of safely stopping a bike quicker than my brain and appendages, I prefer to handle that stuff myself. Bikes are risky and I accept that. My cars get ABS, my bikes don't. I know that makes me sound
but I like simple two-wheeled machines.