In the UK the No Claims Bonus is separate for car and motorcycle and we can have differing amount of years for each. If you have not got a bike for 2-3 years, your motorcycle insurance NCB will expire and you have to start again from 0 NCB. One to remember if you're taking a break from riding for a couple of years, maybe get a little 50cc to insure to keep NCB?
But while NCB is separate for car and bike, the any accidents or claims in the last 5 years question when applying for insurance means any claims or accidents on either car or bike. So if you have a claim on your car policy, it won't reduce your bike NCB, but you still need to declare it and it will affect your bike premium.