The speed averaging option has the following options:
Disabled
Average of last 5 secs
Average of last 10 secs
Average of last 20 secs
Average of last 30 secs
Average of last 1 min
All the options work except 30 seconds. This can be shown by:
Settings -- Activities -- Running -- Speed Averaging -- Average of last 30 secs -- Ok
Press Back
Select Running -- Speed Averaging
==> It is now set to Disabled