The Sandia's classic Knife's Edge is among the most impressive scrambles in New Mexico. Here, I describe what I believe is the most intuitive loop for mountain runners/scramblers who want to challenge themselves. This common variation of the Knife's Edge offers a shorter, yet more technical option that is guaranteed to keep you on your technical A game the entire time.
In general, the trail is not always obvious and at times seems to disappear, so it might be a good idea to use the GPX file if you are not familiar with the area and you want to rip on this course. More Information on the Knife's Edge climb can be found here: https://www.mountainproject.com/route/106242069/knife-edge
Start at Piedra Lisa TH, and ascend 2 miles to the ridge between North and South Piedra Lisa. Proceed right onto the Rincon Spur Trail which will take you to the Knife's Edge. Ascend the Knife's edge and continue to North Sandia Peak. You will end up on N. Crest Spur trail which quickly links up with N. Crest trail and takes you directly to Chimney Canyon trail. Sprint (lol) down Chimney Canyon, but make sure to enjoy the views. Eventually, Chimney links back up with La Luz trail where you can finally cruise a bit. Once at the La Luz parking lot, there is a short connector trail on the northeast side of the lot that will take you back to the start at Piedra Lisa.
Glad to see the Knife Edge on here! Truly a gem of the Sandias. But I feel like there are plenty of worthy descent options and loops that make defining an FKT a bit muddier. I would suggest isolating the ascent as the FKT in the absence of any well established route for the descent or loop.
Here are the corresponding Strava segments for the uphill, the latter being the full ascent to North Sandia and what I would nominate as the FKT route.