hi guys, looking for some advice on tstationary trainer and the bike on it... so i recently decided to get a second hand stationary trainer and want to put a bike on it to get back in shape... problem is, i think the bike is small for me and its not a road bike. does it matter? also what should i take note of?? im doin this more for MTB endurance and stamina. its the best option i have now. also do i need to worry about the geo of the bike? like if the bars are too low? stem too short? etc. appreciate any advise.