I’m looking at getting a 24 inch Muni, so I was wondering what the average distance was that people Muni on a 24 inch and how long does it take.
I can handle about 30 km in 4-5 hours (no rush) on my qu-ax cross 24", but it’s XC, not muni.
Depend on how much time an patience you have. I’ve ridden my KH24 (pre-Schlumpf Hub) 50 miles in around 9.5 hours at a 12 hour mountain bike race once, but had regularly ridden double digit miles in and around my local trail system. If I had to guess I say on average I’ll ride the routes I ride faster than a strong hiking pace but slower than a run (very rocky and cycling-unfriendly terrain around here; trails built for and by hikers originally). With a road tire and Schlumpf hub in my KH24 I’ve ridden as far as 100 miles on a paved bike path between Alabama and Georgia. So really the only limitations are set by you! Good luck!
What size cranks? i would bump to a 26 for speed factor
Colin in the over 55 ‘ride your age’ thread did 65Km on his 24 in one run.
I don’t own a 24", most I’ve done on my 20" is 5 miles and that took about 90 minutes with a break.
I bought a 29 for longer distance road riding, but the local terrain has me wishing I’d gone for a 26" to be honest - really hilly here! The 29, on the flat, is easy to sustain over 5mph on once you get used to it, but on uphill stretches my weak, untrained legs want cranks longer than the 150s with which it came. 
Depends on the kind of MUni. The most technical terrain trails might be only 2-5 miles long, but they can take more out of you than an “easy” xc ride 25 miles long. If I’m out just doing a more xc-oriented ride, I usually take my G26er and the longest trails in my area average between 12-20 miles. For pure, all-out MUni I ride my kh 24 with LM rim and 24x3 dh tire.
Here’s another thread started recently with a similar question: [THREAD=103412]Average Speed for 24 and 26 inch Uni’s[/THREAD]
There I said:
I typically find I’m getting spent after about 1.5 to 2.5 hours, depending on the trail difficultly.
I went back and visited my Strava account for find out my distance and speed were I came up with these times:
Leisure:
3/2) 12.8 miles 2:06:00 6.1 mph on 24" fire roads and flat trails.
My typical 3.3 mile loop around Forest Hill park (hilly) ranges from 31 min to 38min ave. 4.9mph to 5.5mph on the both 29er and 24" I average about a mile per hour faster on the 29er but I am able to climb better on the 24"
JRPS (North Bank, Buttermilk, Foresthill, and Belle Isle loop) MTBR has it labeled as technical takes me about 2 hours with UPD’s and talking to pedestrians. happens to be 8.2 mile loop with an average speed of 5.1 mph I have not separated 29 vs 24!
Races:
Dominion River Rock Race 10 miles race 2:00.36 @ 4.7 mph on a 24"
Xterra Richmond Sprint 10.4 miles 1:52.58 @ 5.5 mph on 29er
18 Hour Scouts Honor Race (8.3 mile loop) 1:38-2:09 range and ave. speed 4.9- 5.2 for total of 41.2 miles. Very muddy race!
It is entirely dependent on the terrain. I don’t measure MUni rides by distance, I measure them by time. Typically we’ll go for 3-4 hours, with some longer days. At our more technical parks, that’ll be 5km of riding or less. At our XC parks, it’ll be 15-20km or more.
The shorter rides are more strenuous.
Yes and we all thought ‘daft’ was right 
Keep working on it, you’ll soon be wanting shorter cranks
I agree, ill ride for hours riding freeride and only got a few miles.
Probably a fair indicator
Frankly I take little notice of the claims of others on the internet. If it is important for you to know then I suggest that you do the same.
I covered 7,843km last year (Or was it 7843?). I hope you will accept this as an honest idea of the upper limit of general capability. It will fall way short of many of the numbers you will read.
I ride a 24" for distance and commuting, not particularly light and no gearing. I ride a mix of cycle path, shopping in the CBD, urban foot paths and local roads. Over time the setup is as I like it and I am totally used to it. I am very fit, and not just for the age. I have an odometer and it shows that I average a little over 10kph after much distance and experience. Occasionally I time a rushed run along a good cycle path and it is seldom 12kph.
Bottom line is I average not much more than 10kph.
I did, a year ago, manage a 12km as-fast-as-I-could-hold-it average speed of 13.8kph on a charity run. That was in ideal road (flat freeway) in perfect but hot conditions. I may have had my backpack (not overly packed if I did) so maybe there was the capacity to add a teeny bit more speed.
A bit of context - the average motorist would be surprised how low his average speed is on the drive in to work. Or over the lifetime of the car. A low sounding number is not necessarily so low as you may think.