There are rumours that there is no parking in Carboot Circus. In the Quaker Friars corner, this is not the case.
There are five sheffield racks with a capacity of ten bikes, an overflow to the (weaker) iron railings. Further along: three more racks.
Leading to a total capacity of secure parking for 16 bicycles.
Which should be enough, if the current stability of the global finance system holds.