You can get 4 on but it is tricky to get the handlebars and saddles to miss each other. The best way with mountain bikes is to take the seat posts out. I have managed 4 bikes. That was 2 adult 26 inch mountain bikes with a 24 inch and 20 inch kids bike. Not tried four adult bikes. Be prepared for some scratching of paint or use rags to pad them. Hope this helps. R
You might have done it already but also staggering the bikes laterally can help as well. i.e one bike as far right as it can go, next one as far left.
I have got 3 adult road bikes on my Altera version in the past.
Some serious fork travel on that MTB btw.
i've had 4 adult mountain bikes on the back, it is tight but it does work.
One thing to note - On the inside bike, turn the handle bars 90 degrees. For the sake of a 20 second job, when you elevate the roof with the bikes on, you won't damage the roof!!
Staggering left-to-right a bit and alternating the bikes front-to-back always does the trick for us... We then have 4 normal bikes on an original VW rack.
You need to drop or remove the seat posts and probably turn at least 2 sets of bars/stems through 90 degrees. Four adult bikes is a push, 3 not too bad. The rack is probably designed for 2 adult bikes + 2 children's.
I find it helps to put the smallest frame on the inside.
There may also be a weight issue if carrying 4 heavy adult mtb's.
I will give it a go with twisting some of the handlebars. To be honest as long as I can get two adult bikes and two childrens bikes on it will be fine.
My downhill bike is much bigger and wider than normal bikes so it's always going to but a spanner in the works!
One other thing to watch out for is the inside pedal / rear wiper interface. Not much space if you use flats.
It takes a bit of faffing to get the bikes on first time but is fine once you get used to it. As I said put the smallest one on first as the clamping bar is quite short.
We regularly put 4 bikes on. But you do need to check the bikes brakes, suspension etc after you take them off. As said before you can not avoid some touching / possible scraping so when I finally invest in my new MTB it will hava a full bike width between it and the next bike... now for the killer quesiton.......
I put 4 adult Mountain Bikes on regularly. Through trial and error I now alternate the bikes and have a specific order which allows them to fit best. I then changed my bike last year and it threw me back into chaos as it wouldn't fit in the same order!!!
I use the seat posts and suspension forks to attach to as this saves the paint work on the bikes.
I often remove the inner most pedal as this fouls the rear wiper arm, as mentioned above. I don't tend to use the rear wiper but Sod's law is that I'll accidentally switch it on and I'd hate to think what would happen when wiper meets pedal!