any one know average mountain bike speed ?

offroad 7 to 10mph.

I use 10mph for estimating solo rides, group rides tend to be much lower.
Edit: That's the overall average(not moving).

Over the last few years me/we've averaged (that is moving average) between 5mph and 11mph, depending on terrain/conditions/weather/fitness/riders etc…

Overally average has been as low as 5.5 mph, am hoping to beat that at the K100… by a reasonable margin!
Usually between 6 and 9 overall though. Would like to see 10 as a moving average appear now I come to think about it…

Organisers of off-road enduro / challenge type rides (ie not races) tend to work on an average of about 8mph when working out where to site feed stations, how many they need to have, that kind of thing.

I generally estimate on 5mph when planning a ride. Seems to work out quite well for me. (planning to enter at least one enduro race this year though, so need to up my game a bit of going to get to the 8mph mentioned earlier…).

So many variables making it just a pointless number.

My mountain bike averages something fairly close to 0mph, as it spends most of its time hanging in the garage.

Probably 5 to 8 miles and hour for me but then I;m no racing snake and it's pretty hilly round here. Usually around a 1000ft of climbing for every 10 miles of riding.