A securing device of a rim includes a rim having a connection bridge and two walls extend from the connection bridge. Multiple installation holes are defined through the connection bridge. Multiple spoke units each have a spoke, a first fixing member and a second fixing member, wherein the first fixing member has a first fixing portion which includes inner threads. A second fixing portion and a third fixing portion extend from the first fixing member. The third fixing portion has outer threads. The second fixing member includes a connection portion having inner threads defined which are threadedly connected to the third fixing portion. By the second fixing member, the first fixing member is secured and adjusted. The second and third fixing portions are reinforced.