CYCLING IS A GREAT SPORT

What Is Your Speed

I've a question concerning the most adequate suspension for a passenger trike (call it a rickshaw if you will) I'm building.
I've set out with CG rear suspension (here's a picture of one)

http://www.tradenote.net/images/users/000/117/351/products_images/CG_CDI_Shock_Absorbers.jpg

Both are placed under each passenger.

I'd like to know if I can get away with using 2 mountain bike frame springs

http://www.sicklines.com/news-images/obtainium_titanium_spring_news_post.jpg

this picture gives you an idea of the dimension, though the one I have in mind is slightly smaller.

The trike is pedal-powered with electric assistance. It will NOT get a rough ride, I'm looking just to absorb extra unexpected shocks that the tyres may not absorb.

Thanks for your answers