Good day , I am from East London and cycle for pleasure only. Grew up on my bike in the 80's and glad t be able to pass this hobby on to my children. I need some info form the pro's. Please point me to where I can request help on the following topic. When my sons bike ( 29 hard tail specialized) is sent in for repairs that is going to take more than a week is it really that bad to train on mom or dads bike( soft tails but also 29'ers) . He belief it will do more harm than rather stay fit and practise on my bike. Thanks