Wow! That is a feat! Congratulations!

There's nothing quite like pushing yourself and finding out that your limits are a LOT farther out than you shought they were.

But hie thee to a bike shop and get a proper bike for centuries, my man! Once you've done one, you're going to want to do another, and another, and a standard century and... you get the picture. If you can do 100 km on a 36 lb MTB with knobbies in just over five hours, you'll have no trouble doing the same distance in less than four on a proper road bike...