You won’t get a BT on a LI endurance ride/workout since you’ll never exceeds TP.
The only way to attempt one would be to insert a max effort of sufficient length (or repeats) above TP to draw down MPA then exceed it for enough seconds to trigger a BT.
The four types of BTs are pull, push, multiple, and near (fakethrough). See second reference below.
Related –
Any tips on using mpa to manage endurance ride? - General - Xert Community Forum (xertonline.com)
Why doesn’t MPA decline on longer workouts? - General - Xert Community Forum (xertonline.com)
Reference –
Understanding MPA – A Story – Xert (baronbiosys.com)
Breaking Through the Xert Way! – Xert (baronbiosys.com)