Non-standard rollerski designs, your opinions/idea's?

Since I've been researching what rollerski's to buy or even which to have
made (budgetary reasons) I've recently come across these :

http://www.rolec.ch/

and these :

http://www.siriro-shop.de/pd10948203...rch0_EQ_Blau%2
0eloxiert_AND_search1_EQ_ohne%20Bindung_AND_{EOL}& categoryId=0

Both sport 4 wheels per ski, supposedly for extra speed in racing, and a
more snow-like feel (they sure are long for skating rollerski's). The speed
I can see, inliner skaters also seem to prefer 5x84mm over 4x84mm for
racing, even if the wheelbase remains the same.

I am especially intriqued with the Siriro Double Quatro's, obviously. Not a
lot of technical info there on how it works, but it looks like the pairs of
wheels sit on a centre pivoting swing arm. I did a little sketch, and it
seems that if there's a 1cm tall obstacle to roll over, the individual bumps
on the frame (pivot point between the front wheels) are just 0,5cm each.
Might be a nice way to get better roll-over ability without larger wheels
than the apparently max 100mm allowed in racing, smart stuff!

Do people actually race or train such 4-wheelers, apart from the sponsored
athletes shown on the Rolec website? How do they compare to the lighter and
seemingly globally popular super-short 2-wheelers?

I'm not really interested in trying a 4-wheel design as my first set of
proper rollerski's (I'm on 10" wheeled Crosskates now), but these advanced
technical aspects do intrigue me.

Your thoughts on these and other "odd" designs out there, please? Any idea
why the Siriro's have 2 differently sized wheels per pair?


For now I'm still most interested in getting a 2-wheel 150mm pneumatic
setup, with extra axle holes for 125mm, 100mm, or even smaller wheels. I've
seen slow 100mm rubber wheels which might be nice for lightweight resistance
training. 150mm tubeless air wheels would be for endurance/technique
workouts over varying road surfaces (copycat of like the V2 Aero 150). 145mm
85A PU wheels might be fun for the occasional silly-fast workout, setting
fast times around my time trial courses, or skiing along friends on bikes.
200x40mm PU scooter wheels exist as well, but will be harder to get to fit a
stiff rollerski to without raising the ride height.
It will be hard to incorporate on the same 2-wheel frame, but perhaps a
setup as the Siriro with two 150mm or even 250mm front wheels and a single
10-14" rear wheel might make for a potent off-road set, weight be damned. I
like that swing arm idea and the halved weight and movement on the front
wheels, and the possibly increased rolling speed over soft soil. My
Crosskates are supposed to be the mountainbikes of rollerski's, but really
roll like crap offroad. I think it can be improved upon for true XC skating
over flowing fire roads I wish were snowed over all winter. Yes it will be
heavy, but my Crosskates are 7.4kg including boots now. Like a road bike on
my feet, and I handle that just fine.
A man can dream?

Happy Easter from Holland,

J