I prefer to have my knifes just above the kitchen sink but apart from an Ikea Grundtal rail + 2 hooks, there isn’t any space for a magnetic bar. In reality, with just 2 knifes; a paring and a chef’s, which are the ones I use most of the time, a bar may not be necessary after all.
The 53cm (21″) rail hangs sponges, a strainer and peelers and it covers almost the entire wall distance behind the sink.
Since Grundtal is magnetic, I’m more than happy to grab my .95cm (3/8″) rare earth and ceramic magnets to setup a mini panel ready for some serious attraction.
The chef’s knife (length = 25.4cm/10″) needs 2 rare earth for a firmer grip.
You can tell that the magnetic grip isn’t sufficient if the knife tilts to the side and/or if the magnet clings onto the knife as you remove that knife from the rail. But all that is solved with the addition of a ceramic magnet placed on top of the rare earth (and not the other way round).
A word of caution if you are setting this up: keep the knife far away from the rare earth until the setup is completed. Be careful when handling very strong magnets and sharp objects, for their mutual attraction to each other is hard to tear apart and you could be the one getting hurt! Ugh. Sounds like a love triangle.