So I'm a bit confused on this subject and wondering if someone can help clear things up.


So I ride 55cm road bike around 22in) but my mtb I have(it's the suggested size for me) is an 18in, which is significantly smaller than my road bike, which fits me fine. I was just wondering why do mountain bikes get sized down so much compared to road bikes. Would it be that bad if I road say a 19' or 20' mtb considering that my road bike fits fine?