Minecraft wiki entry for Minecarts, associated text: Because of this difference, there is also a difference between the optimal spacing of powered rails when used on a 2D track when compared to straight travel on flat terrain. You need powered rail every 53.7225 (rounded to 54) curved rail. This can be worked out through ratios, comparing 8m/s for 38 rails (the optimal distance for straight rails) to 11.31m/s to work out the value of 53.7225. Therefore for a combination of straight and curved, a curved rail is equivalent to 0.707 of a straight rail. To maintain maximum speed, you must keep the value under 38. For example one combination could be 31 straight rails with 10 curved rails as this is the equivalent of 38 straight rails.