why the value of k is fixed to 60?

[kranthi419]

why the value of k is fixed to 60? in RRF.

[Raudaschl]

In all honestly, it felt like the best default value for the use cases I tested.
In many implementations and research studies involving RRF, a k value around 60 has been commonly used.
One advance of setting it to 60 reduces the weight difference between higher and lower-ranked documents, leading to a more inclusive fusion where more documents from different queries contribute to the final ranking.