upgrading shifters

[Cazushio]

hi, new to the forum and need some help.

so i just got a new giant defy 1 2015 to replace my reid condor (http://www.reidcycles.com.au/condor-roa ... irect=true" onclick="window.open(this.href);return false;)
but now my sister wants to start cycling, she finds the hoods really uncomfortable (which it is) and scared to change gears.

i was thinking of getting shimano claris shifters. will these work with the front and rear derailers (shimano tourney), or will i have to buy the whole groupset?

thanks

[Duck!]

They will work, just note the Claris shifters are 8-speed, while Tourney is 7-sp. The indexing works because 7 & 8-sp. use the same sprocket spacing, but you will need to tune out the extra gear in the shifter.