I've searched all I can and came up with more questions than answers. Again, I'm new at all this and trying my best to figure it all out. I know you can mix and match components -IE 105 w/ Ultegra or Dura-Ace. What I can't figure out is if there are specific problems with mixing different component YEARS.

For example, from what I understand, the 105 shifters have been remodeled for the 5700 version. Would having everything ELSE in the 5600 version screw anything up? Or just be poor for performance?

Further, Is there a "rule of thumb" with mixing & matching? For example, Should one try to use the same style Shifters, FD & RD if possible so they all synch up?

Reason I ask: We're trying to upgrade my wife's bike to higher end parts & get rid of her triple crank. We're using it as an opportunity to learn how to work on a bike & do as much as possible ourselves. It seems that buying parts individually on sale is cheaper than just buying a full group (ie. 105 5700). It would give us an opportunity to get some higher end parts (ie. saw a new last year's Dura-ace BB on sale for $25 - the cost of a new 5700 BB) and spend the same amount of money.

Also, this isn't all about the money - we could go out and drop $600 or whatever on a new 5700 group. But if we're doing it ourselves we might as well spend some time with it. AND we have the whole winter to look around...

Thanks so much!