You can certainly use mineral oil to the extent it meets the specification set by your bike´s manufacturer. 100% mineral oil is rare nowadays, though, usually it´s at least "synthetically fortified" or "with synthetic components", which is what I use on the Africa Twin, the Transalp and my VW T4. In any case, change the filter as well.
Generally, fully synth oil has a somewhat cleaning effect on the engine, which sometimes causes a leak on an engine seal to become obvious. This is because the syth washes away some mineral oil deposits in the engine (which may cause an existing tiny leak in a seal to be hidden). Changing the other way round from synth to mineral is not an issue (within the specs, as I said).