Originally Posted by
Leinster
105 is older than Ultegra or Alivia, though. When 105 was introduced, Ultegra was still called 600.
The other groups around then were Exage (which came in 300EX, 400EX and 500EX levels) and, for a while, RX100.
None of it made sense.
I could be wrong, but I think Exage was mainly MTB or Hybrid stuff, so was in the lineup with 100GS and 200GS.
So the pattern did follow the numbers... 100GS, 200GS, Exage 300, 400, 500. Then there was Deore, which eventually split into LX, DX, XT.
100GS and 200GS and Exage 300 became (I think) Acera and a fer different levels of Alivio. Then there was STX and STX RC, then Deore LX, then XT, then XTR.
STX and STX RC disappeared and they brought Deore back. Then LX became SLX.
Now that I think about it, there were Exage road parts (renamed as RX100?), and they were below 105. But above 105 was 600 (which became Ultegra), then Dura Ace.
Sora replaced the lower-end road Exage stuff, RX100 became Tiagra, the rest remained the same.
If you are buying a bike and can afford it, I would recommend not going lower than Tiagra/Deore. And I see no benefit in going higher than Ultegra/XT