What bottom bracket will fit the Ribble Endurance SLR? Will a Shimano Ultegra BBR60 bottom bracket fit the Ribble Endurance SLR frame? I cant seem to find any technical information on the frame anywhere?
Per https://www.ribblecycles.co.uk/ribble-endurance-sl-r-series-frameset/

Bottom Bracket: Press Fit BB86.

A Shimano BBR60 is threaded:

SM-BBR60
SHIMANO ULTEGRA - Bottom Bracket - Threaded - HOLLOWTECH II - 68/70 mm
shell width

So no, the BBR60 won't fit.
Something like a Wheels Manufacturing BB86/92 would fit, though.
And it won't start making noises after 4 km.