Originally Posted by
79pmooney
...The word I heard when I was racing in the mid-70s was that vertical dropouts had taken over in pro racing because wheel changes were faster. Indexing had nothing to do with it; in fact it was years before it even existing at the racing level....
The discussion I see there is interesting but misses the driving timeline of pro racing. The vertical drop switch was driven there before Shimano was even a player in the pro road scene, never mind SIS.
Shimano introduced SIS commercially for the 1985 model year. At that time the vast majority of European pro teams were still using horizontal dropouts. The only exceptions that I recall were were the Vitus based PY10FC of the Peugeot team, the Vitus 979 of the Skil-Sem team and the Alans of the Teka and Varta - Café de Columbia teams.
If you examine 1985 race photos, advertisement and catalogues, you'll find that the the bicycles supplied to the following teams were equipped with horizontal dropouts: La View Claire (Hinault), Panasonic - Raleigh, Lotto (Eddy Merckx), Kelme (Eddy Merckx), Hitachi (Splendor), Sommontana (Bianchi), Carrera (Battaglin), Renault - Elf (Gitane), Ariostea (De Rosa), Malvor (Bottecchia), Gis - Trentino (Moser), Kwantum - Decosol (Colnago), Del Tongo - Colnago, Safir - Van De Ven (Colnago), Atala - Camapgnolo, La Redoute (Motobecane), Fagor (Zeus), Zor (Zeus), Alpilatte (Olmo), Gin - MG (Orbea), Reynolds (Pinarello).
The only major European based pro teams using bicycles with vertical dropouts were those with aluminum or carbon frame frames. The vast majority were still using steel frames with horizontal dropouts. If you look at the bicycle industry in 1985, vertical dropouts were used primarily on non-ferrous frames, grand touring bicycles and ATBs. Yes, there were some exceptions, but the industry as a whole, and road racing in particular, was still overwhelmingly steel frames with horizontal dropouts. Indexing would become the prime factor in reversing that situation.