All mine have been a tick box for more expensive at time of buying the home insurance, incl legal aid. Never added much. Risk is very low for cycles.
But there are website and specialist insurance, a quick search will find the comparison sites do it now.
There is another thread somewhere and I think there was pedalcover a new one by cyclists. Name could be wrong.
There is still the competitive add on etc there too, abroad etc
Also things like locking up in a shed (sometimes a garage, etc) to look out for.
So only cover what is not already covered OR remove anything cycle from you other insurances (to save a few pennies).
I'm just saying, check what you have already.
I think mine is anything over £1000 needs to be written down, anything under doesn't. That value varies with company, some are £500, some £2000.
EBIKES are often excluded and another tick box...