Many of our larger lights feature Overdrive Race Mode. While it's a great feature, it can occasionally cause a little confusion. When you normally turn on or turn off a Lezyne LED light, you hold the button down for 2 seconds, but if you hold the button down for five seconds, either on purpose or accidentally, it'll enter or leave Overdrive Race Mode. This means that all flashing modes are removed from the cycle of modes, and it will only toggle between the highest steady setting and the lowest steady setting.
A great use for this is when alternating between steep climbs and descents. While climbing, you'll be traveling at a much slower speed, so it's a great time to conserve battery with the lower setting. When you reach the top and start to descend at a higher speed, you can hit the button once, and switch to the highest output of the light without having to search through all the flashing modes.
It's also detailed in the manual for the lights. All of our manuals are found here.
Note: In any light before Y11, this is the only way to access the highest lumen output of the light, i.e. your Deca Drive 1500XXL (not the 1500i) only puts out 1500 lumens in Overdrive Race Mode.