Question to radical (部首)"辵" to my understanding a radical is the smallest character you can disassemble a word into (correct me if I`m wrong).

However the radical 辵 seems to be a combination out of two other radicals: 止 (in the form of 龰) and 彡.

Can someone explain?
Your idea is correct, at least most Chinese people agree with this.

But in this case, 辵 is acturally combined of 彳 and 止.


彳 means "walk slowly" or "the step with left foot".
止 means "stop" or "halt".
辵 means "walk one moment and stop the next“.


While 彡 means "plume", obviously having no connection with 辵.

By the way, only 止 is frequently used in daily life; 彳 may occur in some poetry; 辵 and 彡 is never used (unless you are studying the articals or books from thousand years ago).



Reference: 

辵：http://www.zdic.net/z/25/js/8FB5.htm (Chinese)

Sorry, due to my low reputation, I am only ably to post 1 link. You may find explnation for other characters on that website.