Trek killed IsoSpeed — and backed it with data: the original Domane IsoSpeed generation transmitted 19% more vibration energy than the new Gen 5, which pairs a rounded seatpost and updated carbon lay-up. The logic is clean: wide-channel rims and tubeless 32–35 mm tires run at lower pressures do what the mechanical system once did — and Trek decided to ditch the extra 305 grams rather than keep chasing a phantom advantage. Gen 5 isn't an endurance bike retrofitted as a climber; it's a statement that "comfort road bike" as a standalone category no longer exists.