thanks everyone for the advice... it was me posting but I accidentally used the boyfriend's account.
I lift with one foot and push down/back with the other when skidding and I'm fine with the 42/16 so I'm just gonna shove the 19 on the 48 and see if it's easier. My legs are pretty strong from years of bmx and horseriding and swimming - but obviously not strong enough!!
Tyres are a different brand, but I don't see how much difference that could make...?