PAS whether cadence or torque assist will work on any terrain, obviously lower the gear the easier pedalling is. For the front chain rings usually the large or middle one is likely best to use on flat terrain, only using the smaller one if one finds it hard to turn the cranks on hils. For the rear simply select the gear that makes riding most comfortable /easiest.
With the rear gears one has to think a head and change up for easier pedalling when either approaching a hill or coming to a stop. When about to stop say at lights or junction etc,etc always change the rear gears up to the 2nd or 3rd large cog so when starting off again it is easier to get going. If not used to gears then it takes practice to get used to them, forgetting and then changing gears when stopped means a lot of clunking and the pedal leg can slip when the gears finally change.
The front gears very rarely need using unless hills are involved, the middle one will make hills easy and the small one very easy.
Another tip is the easier it is to pedal ( faster cadence) using large gear cogs on the back means less stress on the knee's, if one uses the small rear cogs the cadence is slow , laboured and is known as grinding this can be detrimental to the knee's.
Cadence is a cycle term used to express pedal roataion speeed , this is equal to rpm. A slow cadence is approx. 60rpm or less , 60- 90 a moderate cadence and above is higher or very high cadence. To have an idea of ones cadence simply count your complete pedal rotations over a timed 60 second period of time .
