The 2019 Ryker Rally has a rear suspension travel of 6.9" - rather respectable. I would surmise the rear shock is designed for this.
As mentioned what information was sent to Elka to determine how the rear shock would be put together? A riding profile is hard to determine. Need weights, solo/two up riding, and such.
You mention riding two up a lot. Solo/two up riding percentage: 80/20, 70/30, need estimate. The rally does not have an air ride assist for the rear.
The Elka shock you have does not have a remote adjustable preload setting. You have to manually get at the shock to move the preload collar. Remote adjustable preload adjusters are the best.
The shock spring should have the spring rating embossed on the spring, would be good to know. I installed M2 shocks all round. The rear shock came with a 525 lb/in shock spring, but I wanted a heavier one so as to minimize preload setting. My Spyder also has the ACS system, an auto leveling system for the rear depending on the setting I select. Maintains the ride height when I start to load up the Spyder, or ride two up.
I tried a 700 lb/in shock spring, a bit too stiff especially riding solo. Have settled on a 600 lb/in spring rate and the ride is quite good solo or two up.
I would surmise that you need a new shock spring that has a stiffer spring rate. Since you do not have a remote preload adjuster, would recommend an increase in the spring rate of 50 lb/in to 100 lb/in. This should do for two up and solo riding. Set the preload for two up riding - preload is for ride height only, and left there. Ride quality and performance is determined by internal shock valving and rebound/compression damping adjustments (if available).
I would not recommend any aftermarket shock spring enhancers. It's either the shock spring is adequate for the riding profile or not, if not replace with a proper sized shock spring. Coil over shock springs will be easy to change on the Elka stage 4 shock. There should be enough shock valving and rebound/damping adjustment to accept a modest increase in spring rate.
You can always contact Elka or the supplier you purchased the shock from, have a review of your riding profile, and get a recommendation from that.
Ride quality and performance is a personal, subjective issue. How often do you bottom out in the course of a two up ride? What type of roads are you riding on when this happens? It's not an easy issue to identify and rectify. The same identical shock for a different riding profile may be quite acceptable, and not have the issues you mention.
Having mentioned all this, my first recommendation would be to contact Elka or the supplier of the Elka shock, and discuss a way ahead. My second recommendation, if the first does not achieve your aim, is to do a test/trial program; however, unless this interests you and you are willing to do this, I'd stick with recommendation #1.
Good luck on your quest.
