I draw my recommendation for a day by bike on Easter Island on a map. The route includes the Moais of Tahai, 2 more Ahus, the famous Ahu Akivi (all red) with its 7 Moais and 3 caves (blue).
You start in Hanga Roa with Tahai and take a stop at Hanga Kio’e – Ahu Akapu. Then follow the road to the ticket control office. If you come with a vehicle, you need to leave it here. The path I marked orange is only allowed by foot or by bicycle. And here you already see the advantage of the bicycle. By foot, it is relatively far, if you do the complete way and at the end your vehicle is still in the wrong place. By bike you can first visit Ana Kakenga Cave, then Ana Te Pora, the Ahu Te Peu ruin, spend some time in the great Banana Cave Ana Te Pahu and then leave the park at the other end. Now you are only 5 minutes away from Ahu Akivi, so visit the 7 Moais and then head back to the city via the paved road.
You will find additional information and pictures for each location on the corresponding detail pages.