Hi everyone, I have a city bike, mongoose crossway. the crankset is shimano tourney and the length of BB is 125mm. I tried to put on other shimano crankset on but it seems that the original front deraileur can not go all the way to the outer biggest chainring.

I got the suggestion that if I change the BB to 110/113 and use cranksets other than tourney then deraileur will work fine, Anyone has got any advices on this. thanks