Hello,
I am after an idea of the right size mountain bike and road bike for me. I know it will depend on peronsal preference and feel but I am just after an around about size that I should start looking for. I am looking for a second hand bike, so I can't try a range. So, I am 168-170cm tall. What size should I start looking at.

I notice that MTBs tend to be sized in imperial (inches) whereas road bikes are in metric (centimetres), is it just a matter of converting the values, or are they measured differently?

Thanks.