I was requisitioned to create a more advanced spring rate estimator. The trusty old estimator has served many well, but for those wishing to get their heads around rear spring rate in a more finite way the new estimator is for you. This estimator requires that you input several factors, those include bike and rider weight, spring rate, unsprung weight, and more. Ideally you should use a scale to measure your unsprung weight correctly. The outputs provide insight into the qualities a given spring rate will provide within the parameters of your bike and rider characteristics. The estimator is not without oversights though. Chain pull, anti-squat geometry, non-linear spring rates, and many other factors are not considered. So while the estimator remains a great tool, it should be used with a bit of caution.