Landlord and tenant should negotiate whether they will request waiver of subrogation clauses in their property insurance policies, liability insurance policies, or both (it is less common for the parties to request waiver of subrogation clauses in liability insurance policies, but possible).
Since Nick's answer covered average speed over the entire lifetime of the bike, I'll cover the average over time spent moving. Simply put, this depends almost entirely on the cyclist, rather than the bicycle itself, and there is a wide range. Casual recreational cyclists probably average around 10-15 km/hr (6-9mph). This is your weekend trail rider, out to enjoy the view in the local park.
The answer really depends on a lot of factors (e.g. bike type, terrain, rider fitness, & speed preference, etc.). I used to ride my 10 speed road bike in my neighborhood over a 3.3 mile course & the best I could do was ~22 mph (when I was much younger & in very athletic condition). I'd guess an average rider who rides for general exercise would probably ride at approximately half that speed (~11 mph) on the same type of bike.