As with the past two iterations of the shoe, updates to the Timp 4 included yet another change in midsole material. Altra swapped out their Ego foam for their premium “Ego Max,” which they typically reserved for premium models like the Torin 5 or Mont Blanc. There’s also more of it. The Timp 4 gained an extra millimeter of stack height, going from 29 mm to 30 mm. Some may argue that difference is trivial, but in my experience, the Timp 4 felt far more plush and pillowy than its predecessors (whether due to midsole material or that single millimeter). The shoe hasn’t gone completely soft on me though. In terms of energy return, Altra’s Ego Max feels quite a bit more energetic than both Quantic and Ego foams. It’s slightly denser and quicker than the EVA Hoka commonly uses but still a few rungs below Nike’s “ZoomX” foam. By virtue of the shoe’s zero-drop design, the midsole also feels much more consistent underfoot than models with higher heel-to-toe drops. After testing, I’d liken the Timp 4’s ride to the Hoka Challenger ATR 6 and the Topo Athletic Mtn Racer 2, but with slightly better ground feel than both.
Speaking of which, any time you increase a shoe’s stack height you inevitably impact its ground feel. That makes sense; the more material you have beneath you, the harder your foot has to work to gain purchase and feel what’s underneath it. With the Timp 4, Altra smartly got out ahead of this potential problem by taking measures to add flexibility. A small series of grooves were carved into the top of the shoe’s midsole to add pliability to the Ego Max foam, which Altra calls “InnerFlex.” There are also three drainage ports drilled into the midsole on both the medial and lateral sides of the shoe near the forefoot. When not emptying water (i.e., most of the time for me), these breaks in the foam allow the midsole to fold more easily during foot strike and toe-off. On top of that, the Timp 4 also lacks any rigidity a rock plate might bring. Collectively, this makes the shoe still feel separate from true maximally cushioned models (like Altra’s Olympus 5), which I think is a good thing for most runners. The Timp 4 is protective for runs of just about any distance, but not too overbuilt and lethargic to drastically slow you down during uptempo efforts or on trails that require precise foot placement.