First, make sure you are actually looking at 4K rides (If that's what you're expecting). You can check this in settings.
If you are, that's great. We do everything we can to make the videos look as good as possible, but there are limitations. The nature of video compression is content where everything is moving all of the time requires a larger file size for the same perceived quality as a typical movie scene.
FulGaz rides are shot on GoPros on bikes, and efficient compression becomes difficult when the subject is constantly moving. This means they can never look as good for the same file size as slow moving objects filmed with a cinema camera and lenses.
FulGaz 4K rides have a bitrate of around 21Mbit/s. We are looking at ways of providing a significantly higher bitrate but this presents issues that need to be solved first, namely the sheer size of the files makes them a download only option for 99% of our customers, and it would be difficult to fit more than 2 hours of content on even the biggest Apple TV.
The quality of the image will depend on these factors
1. The Quality setting you have chosen in the FulGaz settings. Make sure it's set to at least 1080p.
2. If you're using an iPhone or iPad and putting FulGaz on a big screen, only the official Apple lightening to AV adaptor will do a good job of this.
3. Try any of the rides in the "People's Picks" category. These are all more recent rides and available in up to 4K.
The Apple TV version of FulGaz looks better than the iPhone or iPad on a big screen because there is none of the downsampling and compression associated with adaptors etc from the iPhone or iPad.
Even if you have a 1080P TV, 4K will still look better because it is a better quality video to start with. Downsizing it to fit on 1080P makes it look really sharp compared to 1080P.