both created by Masami Kurumada, the paths and characters are very similar, but in different scenarios.
If you liked Ring ni Kakero and others of similar style like street fighter, DBZ, etc. then you'll love the original Saint seiya, the Hades chapters and then the Lost Canvas :)
The RNK manga was a stong influence while doing G Gundam,you can see that in the matches,hot bloodedness,the stereotyped nations fighting in Gundams(who in other series are suposed to be Real Robots) using special tecniques is the same kind of desconstruction that Ring ni Kakero does with boxing.The Japan team characters also are simmilar to the Shuffle aliance counterparts,Ryuuji is similar to Domon,Jun to Argo,Ishimatsu to Sai Saici,Takeshi to George and Shinatora to Chibodee.
Kurumada Masami, the original manga-ka of Ring ni Kakero made the manga back in 1978 as his own tribute to Ashita no Joe, except he added his own ingredients which would put Shounen Jump on the map. They both cover issues about hard ships of living on the road, and working hard to achieve your dreams.