Dear Mr.Kohler, Williams AB77 cotterless chainsets are circa 1960's and not 70's. If our clubmen where riding alloy cotterless chain sets back then they would have been riding TA and Stronglight about equal first, then Campag and least of all Williams AB77's. This would aply to the 1960's only. In the 70's the AB's would have been on the hack bikes. It was the Williams alloy rings which were really popular same size as the old Campag, cheaper and very good rings. I can never remember seeing many sets fitted on bikes. Yours fraternally Frank. PS. Do you have a fetish about the obsolete and obscure or is just numbers and letters PX10 AB77?
Frank Cohen Hoxton UK