I'm not a climber or alpinist, but from several book accounts of Everest climbers I had a general gist that it's less about climbing and more about slowly (not) dying. Walking and climbing several steep kilometers while suffocating and freezing to death while simultaneously suffering from several high altitude illnesses (potentially deadly). So more accurate "challenge" would be riding an exercise bike outside in the middle of some winter cyclone for a few days, while wearing a mask restricting your airflow by a quarter and taking laxatives and psychotropic drugs.
As a cyclist, I can tell you that it's not about experiencing the challenge of climbing everest on a bike (and nobody who did it claims that). It is a challenge about gaining a very large number of vertical elevation on a single climb, which requires a combination of endurance, planning, practice and dedication.
Using the height of Mt. Everest is simply a good target because it is a very big challenge to climb 8848m and in addition combines this challenge with the most famous mountain on the planet. FWIW, there is also trenching, i.e. descending the depth of the Mariana Trench, ~11000m, on a single ride (which requires climbing the same amount; https://www.youtube.com/watch?v=dFQ5fVjQACc), and nobody claims that this is equivalent to diving down there.
and notably, if you actually climb mt everest, you start well above sea level so the total ascension is much less than 8848m. Clearly not a direct comparison
In case anyone wants the numbers, Everest base camp to the peak is 3485 vertical meters. But this is done over multiple days. From camp 4 to the peak is "just" 850 vertical meters, less than 1/10 of the 8848m Everesting climb.
My favorite quote from Reinhold Messner who soloed Everest, did it without supplemental O2, etc...
"When I rest I feel utterly lifeless except that my throat burns when I draw breath...I can scarcely go on. No despair, no happiness, no anxiety. I have not lost the mastery of my feelings, there are actually no more feelings. I consist only of will." - Messner on the first solo ascent of Everest
Outside of Everest itself, I'm not sure there is much that can compare except other climbs at similar altitudes.
Thinking about your comment seriously. I am typically all in my head and find myself looking for things to push me to those moments of focus. It’s why I originally found this quote when I was hiking a lot.
This biking challenge can be accomplished on a nearby hill any time of the year, no winter cyclone needed. Most people would be unable to achieve it (training is necessary).
that wouldn't even scratch the surface. ice climbing is always perilous and the mountain is a bigger foe than the altitude. as a mountaineer, every placement could be a fatal mistake, every piece of equipment a potential murder weapon, the layers of ice are constantly tricking you, the weather making its own decisions while the mountain avalanches and ice falls according to its own schedule. meanwhile you are logistically coordinating an impossible set of too many itineraries in many languages on a mostly linear track where simple queueing delay can be fatal for a myriad of reasons.
