Our team used a US Digital MA3 absolute magnetic encoder directly coupled to a small bore in the end of our kicker shaft and it held up great. We used the sleeve bushing model, rated up to 10,000 rad/secē acceleration and 100 RPM continuous top speed, but you can get the ball bearing model (250,000 rad/secē; 15,000 RPM) if you want even more of a safety margin. No detents or hard stops, no gap in sensing, and no wiper wear over time - I would heartily recommend using them in this application (or wherever a pot would be appropriate).
Link:
http://www.usdigital.com/products/en...ary/shaft/ma3/