Read post # 4. ....... Mike :thumbup:
The reason for asking Tucker01 the unanswered question is that 85 octane may work well at or above ~8,000 feet, but might not be best in the 5,000 feet low lands. 8,000' has the same affect as reducing CR ~25%.
Only once did I hear my CB1100 lightly ping and that was in this area, 282 feet below sea level.
The Trail Ridge Road goes above the tree line and is a great drive/ride. When I was there last, there was a herd of elk in the park in Estes Park.
But if the original question is re Denver, which is only 5K feet, then use the recommended octane for max performance.
If riding higher, then lower may be fine, but not the best for returning to 5K feet.
When I lived in Flagstaff (7K feet) running lower octane would not be the best if descending in any direction below the Mogollon Rim.
Back to post one. "Regular" was not identified as 85 or 87 octane.
All other anecdotal replies were from Spyder riders, but this is the Ryker section.
BTW, I ran premium 91 octane at all altitudes.
If the prevailing attitude is "ride more, worry less", why even bother having a forum?