Today I started to replace the 9 speed chain on my Verve + 3 with a new Shimano chain (the system is Alivio). Having removed the worn chain and matched the new one (116 links) next to the factory original, it came up 2 links short... the original was 118. I called my Trek store to ask about it, and their tech guy advised they do that all the time, so I went ahead and installed the shorter chain/recalibrated the derailliers. Seems to be working fine although I found it a bit tricky to tune, but I am new to this. Any downside to this switch I should be aware of?