Can I use an SPD cleat on an SPD-SL shoe; with the Shimano adapter SM-SH85?
No, the SPD-SL adapter was designed to adapt to a SPD-SL cleat bolt pattern shoe to receive an SPD-R cleat; these cleats have built in platforms (pontoons) that provide the necessary stability. You may also use the SH-70/71 cleats with these adapters; these cleats also have pontoons. You can not adapt pontoons if the cleat is not supplied with them and you may not use any other cleat, Ex: SM-SH51 (SPD). Use of incorrect cleat can lead to a malfunction and or serious injury.