Altra Experience Flow ST review

After doing our usual batch of tests and some runs, we recommend the Altra Experience Flow ST for:

• Those with wide feet who want a lightweight daily trainer with added support.
• Runners who are hesitant to try Altra because of its zero-drop shoes, as this model uses a moderate-drop geometry.
• Individuals looking for a stability shoe with plenty of room for natural toe splay and a soft midsole feel.

If you're a neutral runner, the Experience Flow ST isn't the best pick from Altra. Instead, go straight for the Altra Escalante 5 if you want a zero-drop shoe, or choose the Altra Experience Flow 3 for the same platform without GuideRail support.

We also think Altra purists who are loyal to zero-drop shoes will be better off with the Altra Paradigm 8 instead of this model.

We tested the Experience Flow ST in our lab following the ASTM F1976 protocol and found shock absorption readings of 126 SA in the heel and 104 SA in the forefoot.

These results aren't high, but they are fully in line with what we'd expect from a shoe with a moderate stack height. And for daily runs it's certainly more than enough.

The EGO P35 foam from Altra delivers moderate energy return in the Flow ST, with 51.2% in the heel and 60.0% in the forefoot.

That's not particularly impressive, although the slightly better forefoot result is good news because, as with most Altra shoes, heel striking is not particularly effective due to the low-drop geometry.

We briefly mentioned the moderate stack height of the Altra Experience Flow ST, and now it's time to put some exact numbers on it and add another shoe to our database.

Here, we measured 30.2 mm, just 1.8 mm below Altra's 32 mm spec, so the difference is very small.

We also measured the forefoot and found 25.1 mm. Again, that's very close to the official figure and lines up with the moderate cushioning we expect from Altra's Experience line, as well as what we found in the non-ST version.

At this point, you may already know that Altra's Experience line ditches the usual zero-drop design from the brand and moves towards a 4 mm drop. Here in the lab, we carefully measured the heel-to-toe difference and found 5.1 mm, which is still quite close to Altra's stated figure.

This moderate drop makes the Experience Flow ST easier to handle and more versatile than the brand's classic 0 mm drop shoes. However, for longtime Altra fans, a 5.1 mm drop may not be nearly as appealing...

When we tried the Experience Flow ST, the EGO P35 foam caught us by surprise, as it felt noticeably softer than we expected from an Altra and, especially, from a stability shoe.

With a 25.3 AC reading on our durometer, it's quite plush and marks a complete departure from the EGO FLO foam, which disappointed us in almost every way.

We also put the Flow ST in our freezer for 20 minutes and measured it again. It was 48% firmer afterward, a poor result.

Altra skips the rockered midsole for now and keeps it mostly flat, with only a mild forefoot curvature that rises to just 3 cm, less than what we see in most modern running shoes. Therefore, this shoe works best for runners who prefer a more classic setup with a less assisted ride.

The Experience Flow ST uses Altra's Standard FootShape Fit, which sits between the brand's roomiest and narrowest options. It's time to pour some ballistic gel inside the shoe and see what we get...

In our first measurement, it already came in above average at 98.3 mm. That's exactly what we expect from an Altra shoe with the Standard last, offering plenty of room for runners with wide feet.

However, the more interesting measurement for any Altra shoe is always the toebox width.

This is where the foot-shaped design really shines, and we confirmed it with our digital calipers, which measured a generous 80.7 mm.

To finish things up with the fit, we evaluated the toebox height.

Here, we found 27.9 mm, a safe design choice from Altra that provides plenty of space without creating excessive pressure.

One area where we've felt Altra needed to step up its game in recent years is traction, with the obvious exception of its trail shoes that use Vibram. With the Experience Flow ST, however, we found a clear improvement.

A 0.69 score is a very positive result, and in our experience, it provides reliable grip even in wet conditions.

The outsole of the Experience Flow ST follows Altra's classic design, with deep grooves that improve flexibility and create an anatomy-inspired pattern across the midsole. 

Rubber coverage is extensive, with extra focus around the perimeter for added durability. We also found multiple reinforced rubber pods across the forefoot and heel, creating a highly-grippy layout while keeping the shoe flexible.

The Altra Experience Flow ST is still more flexible than average, but it's noticeably stiffer than the Flow 3. In our 30-degree bend test, we found 12.6N, compared with 8.6N for the non-ST version.

One of the biggest strengths of the Altra Experience Flow ST is its lightweight build.

Stability shoes tend to be a bit heavier than the 8.6 oz (244g) we recorded for this shoe, so Altra deserves credit for keeping the weight down.

Altra keeps using its GuideRail technology in the Experience Flow ST, adding substantial midsole sidewalls to provide some pronation control. However, this remains a mild stability shoe, far from the highly-controlled, intrusive feel of more supportive options.

In our view, this shoe is perfect for runners who feel they need a bit of extra support and often wonder if a neutral shoe is too neutral for them. However, if you've been using highly-supportive stability shoes for years, this model will likely fall short.

We found earlier that the Flow ST is noticeably stiffer than the Flow, and the same trend appears in torsional rigidity. Here, we saw a similar increase, from 9.2 Nm to 12.9 Nm, likely due to the stability-focused design adjustments.

The heel counter is very similar to what we'd expect from a neutral daily trainer, scoring 3/5.

That's often the case with shoes offering moderate stability, and we think it's the right choice here because it preserves comfort and a natural feel.

Another clear indicator that the Experience Flow ST is a mild stability shoe is its midsole width in both the heel and forefoot.

We started by measuring the forefoot and found just 114.2 mm. That's slightly narrower than the current average, which helps keep the weight down and gives the shoe a more versatile feel.

The heel is also far from a maximalist design, measuring 92.5 mm. In our view, that's the right choice for this shoe, especially considering its moderate stack height.

Altra has used a different engineered mesh in the Experience Flow ST, and we found that it offers good durability. With a 3/5 score, we don't expect any major concerns in this area.

The heel padding aced our tough test, earning a fantastic 5/5 score. That's an outstanding result.

Unfortunately, we can't say the same about the outsole. Durability was lower than expected, as the tip of our Dremel dug 1.6 mm into the rubber, which was a bit disappointing.

For runners who tend to experience quick outsole wear, this should be a real concern.

At least there are 3.0 mm of outsole rubber, but we still think runners who tend to destroy outsoles quickly should stay away from the Flow ST.

The insole is slightly thicker than what we usually find, measuring 4.9 mm, but only by a small margin.

You can swap the insole for a different option, but as you can see, Altra's shape is quite unique, so not every alternative will fit perfectly inside the shoe.

Altra added large reflective elements to the heel and sides of the Experience Flow ST, and we always support extra visibility at night.

Shoes from this brand often struggle a bit with fit because of their roomy interiors, and that's especially problematic for runners with low-volume feet.

Although the lacing system works well and the flat laces are perfectly fine for us, we found that the tongue can slide around a bit and the laces need to be tightened more than usual to keep it in place, especially around the loop designed to hold it centered.

After weighing the shoe, we initially thought that the lightweight build might have sacrificed some tongue comfort, but the opposite is true. At 10.2 mm, the tongue provides an amazing step-in feel with plenty of plush, comfort-first padding.

The tongue issue could have been easily solved with a semi-gusseted design, but it seems that some cost-cutting measures reached this area.

That's a pity because, in our view, the fit could have been much better with this simple improvement.

There's no heel tab, but we liked the design of this area and how Altra concealed the stitching beneath the reflective plastic vertical strip.

Altra has set a fair price for the Experience Flow ST, in line with what most brands charge for their heavy-duty daily trainers. We have no complaints here, as we believe that despite a few flaws, the shoe earns its price tag.