This was a fairly easy swap compared to front forks. I grabbed a 2018 zx10r Showa shock from ebay. 2016-2021 should all be the same. They go for anywhere from $80-150. Most of them have a green spring but occasionally you can find decent prices on black ones like I got. I haven't been able to find any information on springs rates but its soft.
A couple quick things to know about this swap.
1. The spring on the zx10r is very soft. I'm 140lbs and 5.5 turns of preload got me to 30mm of sag. Basically all the preload available with all the threads engaged. You could get another 1.5 turns probably if you don't mind a thread or so of the preload adjuster not used and above the threads on the shock body)
2. This swap raises the back of the bike 1 inch in height. The shock itself is only 12mm longer which raises the bike 16mm. That was with less than 1 turn of preload though. With 5.5 turns of preload the bike is right at 1" taller in the back
3. Adjusting preload with it on the bike is almost impossible. The preload adjusting ring is directly between the frame so I couldn't a good bite with the shock wrench.
A couple quick things to know about this swap.
1. The spring on the zx10r is very soft. I'm 140lbs and 5.5 turns of preload got me to 30mm of sag. Basically all the preload available with all the threads engaged. You could get another 1.5 turns probably if you don't mind a thread or so of the preload adjuster not used and above the threads on the shock body)
2. This swap raises the back of the bike 1 inch in height. The shock itself is only 12mm longer which raises the bike 16mm. That was with less than 1 turn of preload though. With 5.5 turns of preload the bike is right at 1" taller in the back
3. Adjusting preload with it on the bike is almost impossible. The preload adjusting ring is directly between the frame so I couldn't a good bite with the shock wrench.
