Article by Sam Winebaum
Altra Experience Flow 2 ($140)
Highlights: The Experience Flow 2 is a moderate stack height 4mm drop 8 oz road training shoe with a new softer and bouncier EGO P35 midsole foam and anatomical foot shaped toe box. Altra joins the “fun to run” category with this model competing with shoes such as the ASICS Novablast and Mizuno Neo Zen.
Introduction
With the Experience series of trainers Altra for the first time ventured above their traditional “zero drop” into 4mm drop shoes. I tested the Experience Flow 1 (RTR Review) and others on the RTR team tested the door to trail Experience Wiild (RTR Review). The Wild was a hit, trail favoring somewhat firmer and more stable rides while the Flow 1 was OK but quite firm with its foam what I called out in the review as dated and firm for a modern road shoe.
For the Flow 2 Altra goes with a softer foam called EGO P35. The “35” stands for the Shore A firmness measurement and 35 is, relatively speaking and compared to the prior Flow’s foam which I estimate to have been in the high 30's at least, is a soft foam. The "P" maybe and sure feels like it maybe some PEBA in the blend but this is as of yet uncomfirmed by Altra
Would it be a mushy and overly soft riding midsole was a key question. Even before running them I was quite sure that this softer foam would make the shoe on landings..a zero drop shoe! And not a “negative” drop if they had put the same foam in a zero drop geometry. While out in June, Altra had a few pairs for sale at the Boston Marathon and I purchased a pair.
Pros:
- Light: 8.0 oz / 227g US8.5 sample
- Moderate: 32/ 28 stack height with an appropriate 4mm drop
- No longer “firm and dated”: energetic: soft and bouncy midsole.
- Upper: smooth fitting, broad anatomical toe box with solid midfoot and heel hold
- Altra zero drop loyalist well be happy : effectively zero drop due to soft foam but also not negative drop as a zero drop shoe likely would be with this foam
Cons:
- Needs more front response: wide toe box, softer foam, along with outsole rubber and design and shoe’s flexibility lack toe off snap at faster paces.
Most comparable shoes
361 Eleos
ASICS Novablast 5
Stats
Spec Weight: men's 8.2 oz / 232g
Sample Weights:
men’s 8.0 oz / 227g US8.5 sample (v1 8.02 oz / 226g US8.5)
Stack Height: men’s mm 32 heel / 28 mm forefoot (4 mm drop)
Platform Width: 90 mm heel / 75 mm midfoot / 110mm forefoot
$140. Available June 2025
First Impressions, Fit and Upper
The design makes a statement that the Flow 2 is not a flat on the ground zero drop shoe. Not only do we have a 4mm drop but the “bathtub” rear midsole sidewalls which seat the foot into the platform convey a distinct visual sense of a ramp down and speed. And yes at its light weight of just over 8 oz and relatively low stack height of 32/28 we have a very light daily trainer with a focus on faster runs.
The upper is a dense but relatively thin engineered mesh reminiscent of recent ASICS such as the Magic Speed 4 if a bit thicker and less pliable and stretchy. It is a bit softer than the similar mesh in v1 which was flatter in profile
The mesh provides a consistent very solid hold with the gusset tongue, medial rear overlays and quite thick lacing loop array further ensuring mid foot lockdown.
The very high semi rigid achilles collar and semi rigid heel counter provide excellent rear hold and comfort with the collars moderately padded.
The rear is further stabilized by the foot sitting down into the midsole side walls.
All of this hold and stability is important given the softness of the midsole foam and relatively low 4mm drop as there is no sensation of mushiness, low heel, or instability even at slower paces (which the shoe can handle) while at faster paces the upper and geometry at the rear had me easily directing to transitions off the heel. Really well done.
The front of the shoe of course features Altra’s trademark Foot Shape toe box, here in the “Standard” shape/width and as always. and in particular here, given the uptempo nature of the shoe I am glad not the “Original” fit such as in the Lone Peak trail shoe which for me is only viable for walking and hiking.
The toe bumper is surprisingly high, rigid and extensive for a light trainer and raises the upper “off” the foot more than ideal for my lower volume feet, although wider higher volume feet should be thrilled.
In combination with the soft foam and relatively soft and segmented outsole rubber I wished for a bit more lockdown up front (a lower toe bumper or maybe less vertical upper volume) as I felt my toes were not fully engaged and down at toe off as my paces picked up.
The fit is for sure true to size for me with of course plenty of toe box room.I might even consider sizing down half a size to improve the forefoot hold.
Midsole & Platform
The star of the shoe, and most significant upgrade, is the new EGO P35 midsole foam. The previous Flow and quite frankly most recent Altra with their various flavors of EGO have increasingly felt dated and dull with the proliferation of supercritical foams now moving from racers to trainers.
We do not know what the P35 compound is but the “P” might stand for PEBA but we do know the “35” stands for the foam softness measurement and 35 is a relatively soft foam. It feels quite a bit like the latest FF Blast foam in the Novablast or Salomon’s earlier Energy Foam so it may be a soft EVA with PEBA or Olefin blended in. Depending on the proportions in an PEBA EVA blend can be less bouncy in feel, a bit more taut and rapid responding than what we have here, the Fuel Cell in the New Balance Rebel v4 an example.
Yet these blends can also be bouncier and energetic and the shoe that for me is the closest in feel to the Flow 2 is the 361 Eleos (RTR Review which does have an EVA/PEBA blend.
The big difference between those previously mentioned shoes (except the relatively low stack height 36/30 Eleos) is that here we have a lower stack shoe at 32/28 whereas the others are all pushing 40mm or more at the heel with higher drops. The platform is decently but not excessively broad at 90 mm heel / 75 mm midfoot / 110mm forefoot, the 90mm heel helping with rear stability given the soft foam. The platform widths are the same as v1 except the midfoot which is 5mm narrower.
The resulting combination of foam, stack height and platform delivers a flexible and fun ride with lots of smiles and energy. There is plenty of cushion here at the heel if a bit lower than we are growing accustomed to in the last couple years. So best to focus on a mid to forefoot strike pattern and faster daily training paces and you will have it in its sweet spot. The 4mm drop, please keep it Altra and especially with a softer foam I never felt I was going negative drop, even at slower paces.
Outsole
Continuing that last thought about the heel landings with the soft foam and low drop, the rear outsole coverage is expanded over v1 with essentially coverage of the entire heel area of and, despite the color differences, a single firmness rubber.
Altra Experience Flow v1 Outsole
I note an added rear further forward triangle of rubber on the medial side which helps with a touch of pronation support there
This coverage is key to not only durability but also to disperse forces and respond on heel landings without the heel overly collapsing due to the soft foam above. It all works well with a lively rebound off the heel and quite easy any pace transitions.
The middle part of the shoe has no outsole coverage This, in combination with the lowish stack, makes the Flow 2 very flexible at midfoot with the front of the shoe stiffer but still with some flex.
The front outsole design follows Altra’s usual toe bones aligned approach with longitudinal strips of what feels like a slightly softer rubber than at the heel. Upfront (as with the upper) is where Altra might tune.
The soft foam, outsole rubber and converge could use more toe off snap and response. At easier paces everything is just fine but as the pace picks up i wished for a quicker front return on toe off. Everything is pleasant but not quite as dynamic as I wished for. Might be time to reconsider the long strips of rubber design for these softer foams.
Ride, Conclusions and Recommendations
Altra has of course been well known for “Zero Drop” and Foot Shape fits but less so in recent years for exciting modern riding road trainers. The earlier Experience shoes had them successfully going to a 4mm drop which for many runners (and me) was an easier first step to zero drop and quite frankly I think a more commercially viable approach as well as zero drop shoes are no longer the rage as they were 10 years or so ago.
While the Experience Wild door to trail was very well received by our testers as its denser firmer EGO foam was better suited to the needs of the trail, the road versions were light but comparatively dull and dated due to their midsoles.
With the Flow 2 Altra scores! Of course the anatomical Foot Shape fit continues and should please broader higher volume feet, and the 4mm drop is noticed in a good way at all paces and even slower ones.
The key change is the new P35 foam which puts the Flow 2 squarely in the popular what I would call “fun to run” category with shoes such as the Novablast, 361 Eleos and new Salomon Aero Glide 3.
Energetic, flexible and bouncy, its upper is secure and comfortable. It is relatively stable due to its moderate stack height and geometry and has some well cushioned ground feel something increasingly missing in giant stack height rigid trainers.
I would like to see the forefoot stiffened and firmed up a bit, potentially with a different outsole design or rubber for more toe off response at faster paces as, in combination with the roomy upper, I felt I was not getting the full locked down drive to toe off impulse I believe the foam and platform can deliver and which could improve its range to faster tempos and even plateless racing given its 8 oz weight.
If you are looking for a light and energetic daily trainer with a lower drop that is fun to run and has a broader toe box the Experience Flow 2 is a top 2025 choice.
Sam's Score: 9.25/ 10
Deductions for lack of toe off response/snap at faster paces due to soft foam, flexibility and outsole design
😊😊😊 1/2Comparisons
Novablast 5 (RTR Review) has a similar riding foam and more of it as it weighs 8.75 oz / 247g in a US9. It a more max cushioned 41.5mm heel 33.5 forefoot stack height to the 32/28 in the Altra. Both have roomy toe boxes and are true to size. I prefer the more flexible, agile and lower geometry of the Altra for shorter runs and the added cushion of the ASICS for longer runs.
361 Eleos (RTR Review) is the most similar shoe in my view. Somewhat higher stack at 36/30 but still moderate for 2025, it sits on a considerably broader 100 mm heel / 85 mm midfoot / 120 mm forefoot platform. It has s a very similar riding energetic foam. The broader platform makes it less agile than the Flow although I find its stiffer more rocker based profile more responsive up front on toe off. Its upper is true to size as is the Flow’s with plenty of toe box room but lags in hold compared to the Altra’s as it is baggy and overly soft and pliable.
Tester Profile
Sam is the Editor and Founder of Road Trail Run. He is in his 60’s with 2025 Sam’s 53th year of running roads and trails. He has a decades old 2:28 marathon PR. These days he runs halves in the just sub 1:40 range if he gets very, very lucky. Sam trains 30-40 miles per week mostly at moderate paces on the roads and trails of New Hampshire and Utah be it on the run, hiking or on nordic skis. He is 5’9” tall and weighs about 160 lbs, if he is not enjoying too many fine New England IPA’s.
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