I have a Silvertip coming soon and was thinking about shooting aluminum! the bow will be 55# @ 28" and I pull right at 28" so it would be 30 to 301/2" shaft! looking at the easton legacy,125grn woodsman, 5" sheild cut feathers! What would be a good starting point? 2018, 2020, etc... Thanks,Jason

2020 will work so would 2117's and 2216's  I have shot schafers for years in your weight range and although my broadheads are much heavier with insert 225 grains I have found these shoot very well..  2020 deflection is .426.  2117 is .407,  2216 is.376,  2018 is.464 the longer the arrow the stiffer I'd go I also shoot off a rubber rest.  Hope this starts you out-

Congrats on getting an S-tip! I'm sure you'll love it. Please post pictures when it arrives.

Covey,
Congratulations on the tip. To answer your question you need a little more info. Are you shooting off your shelf or elevated rest. This will make a difference for the spine weight you will need. I shoot an elevated rest and my tip requires a lot of spine, I'm shooting Grizzlystiks Alaskans 27.5" long, standard 70 grain insert and 145 grain tip. 17.285 FOC not high at all for the Alaskan, My point is the tip requires a lot of spine from what I have found. Our draw is real close, I have done a lot of  work finding the right arrow for my tip PM me I will give you my number if you need any help finding the right shaft. Some of my friends that have tips shoot aluminum shafts and elevated rest, Good luck  

I shoot Schafer 3 pc recurve, 55#'s @28" using 60-65# POC, and 2016 aluminums, both shafts have 125 gr broadheads, both shafts are 29 1/2" long.
I shoot off a Bear weather rest, which makes the bow less spine sensitive in my opinion.

Billy

Nice, love mine. My specs are 50lbs @ 28", my draw is 27". Mine likes 2016's and are cut at 29 1/2". I also have 100 grain brass inserts in them as well. I think the 2018's will work fine for you. Good luck and make sure to post some pict's for us to drool over.