The Leadville Trail 100 MTB race is described as "...the race of all races. One hundred miles across the high-altitude, extreme terrain of the Colorado Rockies, this event was created for only the most determined athletes."
Coming from 2,200ft elevation less than 48 hours before the race started, I gave it a shot, having prepared almost entirely indoors: 216 rides in the 223 days Jan 1-Aug 11, 2017, 155 of them (71%) indoors.
This was my 8.5 hour race, in a little over two minutes:
So the answer is yeah, you can take on some really big outside challenges preparing mostly inside.
If you're curious, my indoor protocol generally looked like this:
1. Zwift for endurance rides of 3-4 hours. I'd ride on my own primarily, dropping into group rides to make the time go faster. 1x per week at most.
2. Zwift for races, usually in place of structured intervals. My peak TSS per hour and peak power outputs were all achieved in Zwift races.
3. Trainerroad for structured intervals, at least once a week, or twice if I didn't do a Zwift race.
4. Virtualtraining.eu now Rouvy.com for long (60 min to 2.5 hours) climbing simulation.
And yes, the above means I subscribe to all three of the most popular indoor training apps. At less than 45 Canadian dollars/month, they get used far more often than my gym membership, which costs 2x more!
Highly recommend the Leadville Trail 100 MTB get on your bucket list of rides, btw. One of my best days on a bike ever. Or it seemed fun, anyway, maybe because my brain was low on O2..
Thanks for reading.