1RM’S GIGANT RIDER is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Reincarnated as a nameless commoner on Raniakea, the continent of magic and steel, with memories of 21st century Earth. To escape the life of a commoner, who is almost like a slave, he must lift the 'Magic Stone' and become a Giant Rider. ‘Straighten your back!’ ‘Tighten your belly!’ ‘Take a deep breath into the bottom of your abdomen!’. He uses knowledge from his previous life as a trainer to accumulate magical power as if he were exercising, and climbs the ladder of the social hierarchy.