Question: What is the number of riders that had a Tues 31 May time of 18' 55.91 124.236mph?
Schema: create table table_29218221_2 (rider varchar, tues_31_may varchar, PRIMARY KEY (rider))
SQL: select count(rider) from table_29218221_2 where tues_31_may = "18' 55.91 124.236mph"