Four metal blades upon which the bobsleigh rides. Bob athletes learn different sanding techniques and have different runners for various track and weather conditions. Alloy composition and shape can also determine runner performance. Found on http://www.cbc.ca/olympics/history/story/2009/11/25/spo-glossary-bobsleigh.
Two highly polished steel sliders on which the sled rides. It is prohibited to heat the runners or treat them with any gaseous, liquid or solid substances in order to improve their sliding capabilities. Found on https://www.encyclo.co.uk/local/21309