Your approach is nearly identical to mine. I’m 40 years of age and only have a couple of years on the bike. 1x full round of TR following SSB 1&2, and SPB in LV format plus outdoor mtb rides. XCM specialty in MV leading up to my races. 100km, 68km and 43km with a fair amount of climbing.
Firstly, loads of great advice from others above.
My experience is that it’s pretty easy to give myself cramps. Especially after doing SPB. I mean it’s really just a block where you extend your ability to tolerate efforts above threshold for big chunks of time.
Every race I’ve completed has ended in me crossing the line with my legs starting to cramp. I know in my head it’s almost over and I can push a little beyond my capabilities.
Add to that the fact that I tend to push a lot harder during races. 75%-85% is the norm for longer efforts.
Coach Chad touches on the subject in the latest podcast 208. They discuss the way training overwrites the bodies self protect mechanisms. All well documented and tested theories to my knowledge.
Worth a listen. As are the podcasts based around the failed Single Track Six attempt.
I’m thinking that because you were able to carry on afterwards it was a pacing issue more than anything else. XCM is brutal and you can easily be pushing well above your pay grade on the steep climbs that don’t give you much other option.
Sure, you won’t be able to do the same thing on the trainer in two hours, but there’s no reason why you can’t get your fitness fine tuned on there.
I figure you now know how to recover from cramps and complete an endurance event. That’s a big jump in experience in my books.
I’d be chasing those cramps on my outdoor training rides to get a good feel for my boundaries before race day.
Best of luck with your next race.