In engineering the worst case scenrio is what one has to design for.
That's right Ji, thats why I mentioned it.
The reasoning for worst case scenario (for a wheelstand) being w the front wheel just off the deck is that the more altitude the front wheel has the more of the total combined weight of bike & rider is taken by the swingarm tubes (ie from the axle thro the tubes to the pivot) & less by the shock/springs until you get to near vertical when all the weight is taken (rigidly) thro the swingarm tubes & none by the shock/springs & the only effective suspension is the flexibility of the rear tire.
I'd have tho't the 97-143 progressive springs would be way too stiff if the shocks are in std pos'n unless yr very heavy. CZs came std w 100 or 110lb springs back in the day & they were way too heavy (& just about the first thing replaced) unless the rider was "over 230lb"
For my wt (71Kg/154lb) the 74-102s would be much closer to the mark, which is approx equiv to 88lb straights, & even that would be a bit stiff. Back in the day 60-90 progressives were widely used, or 68lb straights unless the rider was over 180lb when 78lb straights were used. The 57-85s would perhaps be the best for my wt as I like fairly soft suspension.
Using Ochletree's corrected formula (Reply # 60), for 240lb bike, 160lb rider, 0.6 balance factor, 2.0 load factor, 1.2 shock leverage ratio, & 4" spring/shock stroke, it gives 72lb springs - very close to what we ran back in the day. All calculations aside, thats what worked well on the track & in the end thats all that really matters. It'd be worth calc'ing the sag/ride ht for them.
