You might be coming somewhat insulin resistant (high trigs is one sign of that).
IR with high carb diet will be detrimental to health in the long run.
Has happened to some endurance athletes. If you are in the USA.
Get a more advanced NMR lipoprotein test.
It will also give IR score. Fructose cant be directly used as energy by other cells. Only liver can use it.
Liver can only store about 400-600 carb calories. Some of the overflow will be packaged as trigs.
Also Check yout Peter Attias work on ketogenic adaptation.
And listen to Dr thomas dayspring (podcasts and youtube) about lipids.
I am somewhat keto adapted (i dont need more than 100grams of carbs whole day, which i get from sweet potatoes. I follow a paleo diet so i dont eat any processed stuff)
I can do 2 hour rides completely fasted. I havent tried any longer.
I havent bonked for ages. Cause i can run on ketone bodies now as well
. I drink coconut milk and oils for fuel.
I rather do some more varied training now, like barbell weight training and other forms resistance training.