I have worked with lots of Fijiians, a larger proportion of them tend to be bigger and have lots of strength/power. Imho there must be people within most phenotypes who could make great cyclists,(pick any spot where there are large mountains that people have inhabited for a very long time) but they need to have the right physiological features. Poverty probably has a lot to do with it too, training for cycling needs lots of time which perhaps a lot of folks around the world dont get access to.