Sorry if this may be a stupid question, but my tires tell me to inflate to 7bar 100PSI / 8.5 bar 120PSI. Does this mean keep it between 100 - 120 PSI? What's the 7bar/8.5 bar mean? Thanks! -D

The PSI ratings on a tire are safety ratings. The "best" PSI level depends upon the actual (measured) width of the tire factored with the weight of the rider and bike.

Generally, if the load on a tire is above 200 pounds, the "best" PSI level will be near the maximum stamped on the tire. A medium weight load (170 pounds) should use 10% or 15% less than the maximum, and a light load (110 pounds or 130 pounds) makes it best to use 15% or 20% less PSI than the maxium.

So, if the "maximum" marked on the tire is 100 PSI, the heavy rider would use 100 PSI, the medium rider 90 PSI, and the light rider 80 PSI. Each of those riders would create an identical contact patch on the road, and an identical sidewall profile. Each of them would experience about the same ride quality and have the same amount of rolling resistance.

The best performance for a tire is when is has about 15% deflection. That means that the distance from the bottom of the rim to the pavement decreases by about 15% when you get on the bike. If someone is standing behind your bike when you get on, they should notice a very slight drop in the rim, and a slight change in the side profile of the tire. If there is zero deflection, you will feel every bump in the road.

If you hunt for old PSI threads, you will find links to published charts that use the measured width of tires and the total load on the tires. Those charts are a good starting place, although you may find you prefer 10 PSI more or 10 PSI less, depending on how rough or smooth a road is, or how wet or dry a road is.

The case for a lower tire pressure: https://www.roadbikerider.com/UArant.htm
Makes sense to me.