E-Bike insurance does it for me. I use their monthly "pay as you go" policy and can put bikes on/take them off on the net in minutes and you're covered immediately (handy if you want to have a sunday blast on your mate's bike). You can have up to 4 bikes on there and you accumulate a year's no claims bonus every 8 months.
Was with carole nash when I had my bmw, then bought a st4s, nash wanted loads more to have the 2 bikes on same policy. Then went through ducati insurance and got both bikes far cheeeeper, but then i'm no spring chicken
I have three bikes and Ebike were by far the cheapest and easiest to deal with. As said elsewhere they also have a sensible attitude to Termis and other extras and are more sensible on aftermarket security measures.