Here is the compatibility chart from Shimano:
http://www.google.ca/url?sa=t&ct=res...P_d7sZ3iy3AM5Q

According to that chart, SH70 (no float) or SH71 (float), both with pontoons, would be usable with your M505. However they are in the "usable" category, not "recommended." So it will work, but perhaps not as well as other systems would.

The complex bit is that the chart does not include compatibility between your shoes (which would be in the road category, probably a model that came after the chart was made) and the cleats + pedals. I don't think you'll get a definitive answer to that unless you call Shimano's customer service. This being said, the cleats are $30 and you can probably return them if they are not compatible.

Let us know how this turns out. I am curious about those pontoons things.

Quote Originally Posted by HoosierGiant View Post
Current road bike set-up: Shimano SPD pedals (M505)
Current shoes: Answer MTB with SH51 cleats
New road shoes: Shimano R085

Info with the shoes indicates I need to use cleat SH70/71, which incorporates a pontoon system for road shoes. But, I can't seem to find a definitive answer as to whether that cleat system will work with my 505 pedals. All the compatibility charts I've seen are missing one of the components I'm looking for -- show the cleats but not the pedals, etc. Help!!!

I like my SPDs and am loathe to switch to road pedals since I've never had an issue with them. And, in a perfect world, the new set-up will work exactly like the old... same degree of float, same release maneuver, etc. (I don't like change.)