RideBack

These animes have a somewhat similar plot... - The main character of both series discovers something that they have never seen before and the plot will start to build from that point on... - In both animes there are competitions or races where the characters will need to improve their skills to be able win for their teams or just to be able to help their friends in need... anyhow ... if you like one of these animes, then i'd bet that you'd like the other aswell! ;) 

Both shows feature a few teenagers who are interested in mecha and the setting is in the not-too-distant future. The teens spend a lot of their time in a garage and discuss the robots. Also, in both of the series, there is a bit of politics/conspiracies mixed in. Although the vibe of both series are a bit unlike each other - some of the character's personalities in both series are similar to each other. For example, both the RN and RB main female characters are persistent and are focused on reaching their goals and have a bond with their robot/RideBack. 

Both have motorcycle type mechs and each show has some sort of military/government centric plots. 

Both animes are similar in a sense that both features the protaganist riding in a robot like vehicle and discovering the possibiliries it has in their lives. 

Racing takes place in transforming mecha-type vehicles. 

Both are interesting futuristic animes with the lead character discovering who they really are. 

How race and bike change everyone live in both anime ? That question become main theme in both anime. Also, there are theme of sports as MC experiences and gain skills involving such sport. The sport is highly competitive and there are other competitors. 

powerful females that are chased by government agencies 

Both cover racing although Redline is more focused on racing with cars were RideBack more focused on MechaBikes and also has a quite nice and touching story to it. 

Both involves bikes that look great both have somewhat of a plot nothing great still more plot than Michael bay stuff. But the anime is more like sit back and watch it nothing insanely complex but a fun watch. 

To paraphrase a Phineas and Ferb meme: "If I had a nickel for every time a teenage female protagonist named Rin quit her ballerina career due to an injury, then decided to change her life after finding some hi-tech vehicle thingy, I'd have two nickels. Which isn't a lot, but it's weird that it happened twice." Also, Highspeed's OP singer voiced Rideback's protagonist! 

Both series feature plots in which the main character is caught up in terrorist groups, and have an oppressive international organization acting as the ruling regime. In RideBack, Rin gets caught up in these things due to her natural talent and skill with RideBacks, whereas in Guilty Crown, Shuu gets caught up with it due to a power he came to inherit. 

Both are female-led mecha series that heavily feature political and military drama, realistically grounded machines, and a gripping atmosphere. 

From first glance, Rideback seems to be fun-spirited for the most part. But similar to School Days, it escalates QUICKLY into something intense, shocking, and screwed up.  

Now I know what you might be thinking, boxing and biking and not much alike, but the story i have seen so far in Ride Back seems to indicate these two animes have alot in commen. Rin Ogata and Ippo both find a new thing to do with their lives, they are both a bit lost when they are not doing the thing they love in the ring and on the race course and they work hard at their new dreams. The best art is saved for the main themes of the story, like the Bikes In ride Back and the boxing in Hajime no Ippo. read more 

These anime are similar in the concept of competitively racing of stand-up motorcycles on track circuits. 

I'm surprised no one made that obvious one. Both happens in the future, and uses some kind of motorcycles to turn the tide of a war ; which proves to be very effective against much heavier/slower conventional weapons and vehicules.  

The main protagonists go through a lot of things in their mind while trying to overcome themselves. Both series deal with similar problems and politics, and have psychological aspects. Despite being scifi stories, both have a kind of sense of realism by introducing technologies that feel realistic. And not to forget the mature drama that's present in both. 

Series as much concerned with government corruption, political unrest, and societal revolution as they are with the mech gimmick that become the trademark vehicles for rebellion and resistence. Both deal with a core group of students, some with tenuous ties to those in power and others with no connection at all, who gradually become increasingly involved in the political situation, and both have a relatively recognizable setting -- the near future in the case of RideBack, and a contemporary alternate timeline for Code Geass. 

A ragtag group of students with a similar interest, an otherwise mundane technological development they utilize choose to use for good, and a healthy dose of shady organizations and underhanded dealings. 

RideBack is about motorcycles and OverDrive is about bicycles, leading to similar events ... racing. The main character in each series starts out with a lot of hidden potential, they both learn quickly and enough to reach the level of their coaches - even personality-wise, they both seem shy on the outside but have a fiery competitive spirit that shines as they ride. RideBack seems to have a more elaborate plot, but I'd say both series would please to the same audience! 

Another anime about racing on mechas. The art is quite resembling (CG mecha designs and 2D characters). In both animes main character is a girl. 

Both of those series uses terrorism and international war context to set the plot and the mecha is one of the central element of the series. Also the everyday life of the protagonists is an important part of those two series.  

Both series revolve around a university sports club. RideBack steers dramatically away from sports after a few episodes, but if you wanted to watch more young adults enjoying sports and camaraderie, Kaze ga Tsuyoku Fuiteiru might be what you need. If you liked the latter and also enjoy action and mecha, then RideBack is a must-watch.