Why does it have 4 positions that I can shift into? If that does not make sense, what I am asking is why can I start in the small ring and then when I shift up there are 2 positions that it shifts into for the middle ring and then finally if I shift up once more I am in the big ring. I bought a bike online and I am tuning it up and this makes no sense to me. I know how to fix it and I am going to get to it this evening, but I am wondering what the purpose is. Thanks in advance.

Fred

Why does it have 4 positions that I can shift into? If that does not make sense, what I am asking is why can I start in the small ring and then when I shift up there are 2 positions that it shifts into for the middle ring and then finally if I shift up once more I am in the big ring. I bought a bike online and I am tuning it up and this makes no sense to me. I know how to fix it and I am going to get to it this evening, but I am wondering what the purpose is. Thanks in advance.

Fred

The STI triple front has a 'half-shift' to fine tune the cage while on the small chainring, so there's no chain rub when using the smaller cogs in the rear. If yours is immediately shifting from the small to the middle ring on the first click, then it does need some adjustment. The shimano website has manuals & diagrams online for the 105 line.