If your ride is on nicely surfaced roads with a shoulder then you really want to be on your road bike.
On the other hand if you’re riding single tracks with plenty of technical terrain then you want to be on you mountain bike. But than there are all those in between rides eg partly on tar and partly on gravel or roads that have a very borderline cover and no bitumen shoulder. If you want to be confident that you can pull onto a compacted dirt shoulder whenever needed than a gravel bike is the answer.
I recently tested my gravel and mountain bikes on the 40 km Flat Tops loop near Dungog and I was 10 minutes quicker.
The stand out differences for where for the MTB
The big tyres create a lot of roll resistance
the top end of gears you simply don’t have big enough gears for downhills and fast sections
The extra weight for suspension gives you no real advantage on flat surfaces
Downhill handling on fast gravel sections is better
Gravel bike give pros and cons:
  • Often a great option for Triathlon training if you can use a course with a lot less traffic, making it safer but similar to road riding
  • Is lighter and more big gears make it quicker and more fun on somewhat smoother terrain than a MTB
  • Dropbars are great for a better aerodynamic position on down hills
  • The front does get very bouncy on fast but rough gravel downhills
  • On steeper uphills, not having as many low gears means that I had to dance on the pedals for the really steep pinches.
Bottom line is that if you’re riding varied condition roads the gravel bike is certainly quicker and just is more fun!