Originally Posted by
lucille
Just do what you said in the original post: brakes, more efficient gearing
The difference between the most and least efficient Shimano derailer powertrain is probably something like 2%. And you have to cube root that to get the speed difference.
When I bought my 2004 Sirrus, I fell in love with that bike, it felt like it was a part of me. Unfortunately after a few years I noticed a crack in the frame and had it replaced with the current model
That Sirrus model had a rep for very weak frames - it seems strange to buy a replacement for a defective bike from the same manufacturer.