Methods, systems, and devices for wireless communications are described. A wireless device may receive a configuration for a first random access message of a two-step random access channel procedure. The wireless device may select a subcarrier spacing and a number of demodulation reference signal occurrences for transmitting the first random access message based at least in part on the configuration and a speed of the wireless device. The wireless device may transmit the first random access message of the two-step random access channel procedure using the subcarrier spacing and the number of demodulation reference signal occurrences.