4K HD Wallpaper: Girl on Bike at Dusk
Abigail Keenan is the photographer behind this picture that can be downloaded from her courtesy under CC0 license. Check the image at full size and if you download from here optimized for use in your desktop backgrounds and homescreen phones.
Widescreen Desktop / Macbook (Retina): 2880x1800 (fits on: 2560x1600, 1920x1200, 1440x900)
High Definition HD 1080p: 1920x1080 (fits on: 1600x900, 1366x768, 1280x720)
Samsung Galaxy Tab & iPad: 2048x2048 (compatible with many tablets)
HTC, Samsung Galaxy & iPhone: 1080x1920 (compatible with many phones)