The DR 37 between the NR17 and the NR18 in Kinigi is a "dirt road". Depending on the season, the surface may be more washed out or more compact. Some of the surface is covered with volcanic gravel and can be dangerous for tires. This section can be ridden with a gravel bike (40mm tires and more). In some places it can be rougher, then a suspension bike (MTB) is more fun.