Specialized Sirrus Parts
 

I have a late 1980s or early 1990s Specialized Sirrus road bike with Shimano 105 group.

I can search the internet for replacement parts, but sometimes the compabitility isn't clear or I don't have the actual part number I am looking for. Recently I tried to find replacement brake hoods, for example, and couldn't tell if the hoods were a match for the Shimano 105 "super SLR" brake levers or not.

Is there a good way to find out exactly what is on my bike - like a parts catalog?

Shimano has series designations for parts. The 1987-1989 105 was the 1050 series. In 1990 they introduced the 1055 series, which was 105 SC. Sounds like you have the former. All the major components should be stamped (usually on the back) with the part numbers, which will consist of the series number and a two letter prefix indicating the part type (i,e, BR = brakes, BL = brake levers, FC = crankset, FD= front derailleur, RD = rear derailleur, CS = cassette, FH = freehub, etc.). For instance, if you're looking for 1987-1987 brake levers with hoods, you want BL-1050.

awesome thanks! I'll check tomorrow. It has Wolber GTX wheels and I think I read somewhere else that this helped narrow down the year.