When I try to run the triangle offense at fast pace my teams fall apart. Only have this problem with teams where I run the triangle. Motion and Flex teams are ok. Any reason for this?

I run fast paced triangle a lot. Never seemed to notice any difference than any other set. I'd be interested if others have the same experience you have.

Offense is not the same in Triangle, than in Flex and Motion, but a good player is a good player and PIMAN, you get good players.

In my experience, an uptempo in any set works best when you have speed and ball handling advantages over your opponents speed and defense. Speed and ball handling are not as high on my list for recruiting with the triangle, but I imagine if you have speed and ball handling, uptempo should be fine, in theory. If your triangle is built around "finding the open man", emphasizing passing over ball handling, and per/lp over speed, then it's more built for normal or even slow down pace, and may not work well in uptempo. Just my 2c.

consider whether your triangle teams have less depth than your others - in terms of depth of players and/or the stamina of your players. or depth of IQ. If less depth/stamina, thats it.