"Great bit of advise… save the cash, to put towards the next bike?
(the elder must be due a growth spurt?)"

My 9 year old is small and will prob be on this bike for at least another 2 to 3 years, the younger one maybe even longer, so we are looking for something longer term. . .

Cheers for the help so far. We are taking our boys to the alps this summer, but you are right they don't really 'need' disks. There is plenty of stuff on my bike I don't really 'need' (I am sure we can all relate to that). They just 'want' some for their bithday and their dad is c**p at adjusting v-brakes (and so am I). The v-brakes on the bikes are not that good, so we could also just upgrade those for ones that don't need adjusting as often. . . . but that is not really what my boys are after.

…Mmm thanks for all that. I may try a stinger. Sorry to sound ignorant, but which fitting should I get for the Hustler? Thanks again Simone