Nike Flex Train review

We believe that the Nike Flex Train is a great option for beginner gym goers who:

• need a do-it-all trainer
• focus on HIIT, cardio, machines, and strength training with lighter weights
• want a durable pair on a limited budget

If you have moderate-to-severe overpronation or simply want more reliable lateral stability even in a cheap trainer, the Nike MC Trainer 3 is the way to go. It feels like a takedown Nike Metcon!

And if you don't mind stretching your gym shoe budget for better overall performance and the ability to lift heavier weights, we highly recommend the Nike Free Metcon 7.

The Nike Flex Train appears to be a budget-friendly version of the Nike Free Metcon 7, and much like the latter, it offers more impact protection than the average cross-trainer, particularly in the rearfoot.

We measured the Flex Train's shock absorption at a high 104 SA in the heel and a standard 58 SA in the forefoot. It ensures much better-protected landings for plyometrics than the other trainers in its price range.

But if you prefer better cushioning in the ball-of-foot area (for cardio and aerobics), the Nike MC Trainer 3 showed a higher forefoot score of 83 SA.

In addition to keeping landings safe, the Frex Train's midsole also has a touch of rebound. Nothing crazy as its energy return is still below the average at 49.3% in the heel and 49.6% in the forefoot. But it's just enough to prevent the ride from feeling dull.

Even though our caliper recorded a slightly above-average heel stack of 26.8 mm, it doesn't feel excessively tall or towering.

The shoe's forefoot stack proved to be within the average at 17.0 mm.

The difference in stack heights results in a slightly above-average drop of 9.8 mm. It is an optimal setup for beginner gym goers as it feels familiar to most running shoes and sneakers on the market.

It also feels more comfortable for treadmill and elliptical workouts, as well as for aerobic classes, putting less strain on the Achilles and calves.

The Nike Flex Train relies on a basic full-length foam midsole made of firm EVA.

It is not easily compressed with a high durometer reading of 48.5 AC, making it feel stable underfoot.

We created a one-to-one gel cast of the Frex Train's interiors by filling them with custom liquid and letting it solidify in the fridge.

Measuring the replica's widest area with a digital caliper, we recorded a solid medium-width reading of 97.6 mm.

But if you need even more forefoot space, this trainer is also available in a wide version.

And looking at the shape of its toebox, we didn't see any aggressive tapering in the Flex Train. Its standard dimensions also showed up in our caliper measurement of 73.7 mm in the big toe area.

However, this Nike trainer can feel restrictive on the toes, as we found its vertical space rather limited.

With a below-average toebox height of 25.3 mm, the shoe's upper material sits rather close to the foot.

With a moderate friction coefficient of 0.27, we found the Nike Flex Train sufficiently grippy for a wide range of gym uses. Its average traction prevents slips during box-jump landings, multi-directional aerobic movements, and other dynamic exercises.

But it's not the tackiest of training shoes, if that's what you prioritize.

The shoe's limited grip is partly explained by its limited rubber coverage, which lines only the most strategic areas around the platform's perimeter.

We can also see its deep flex grooves starting quite early on in the midfoot, followed by thin slits in the forefoot, to ensure plenty of flexibility.

The Nike Flex Train clearly deserves the word 'Flex' in its name, as its midsole cutouts allow for rather deep bending.

Fixing the shoe's forefoot in place, our machine recorded that it takes merely 8.4N of force to bend it by 30 degrees.

With its simple design and the absence of bulky stabilizing components, the Flex Train is fairly light for a training shoe (minimalist trainers aside).

Weighing it in a men's US size 9, we got a below-average reading of 9.1 oz (258g) - the lightest in its price range!

The Nike Flex Train employs a rather porous mesh to help release sweat and maintain airflow inside the shoe.

But as our smoke-pumping test showed, its ventilation capacity is only moderate as the flow is partially blocked by an interior lining beneath the mesh.

That's why it looks only semi-transparent in our light test.

Yet, examining the mesh itself, we found the pores to be fairly open, which put our breathability score in the middle range at 3 out of 5.

Our simple ankle-shifting test makes it clear that the Flex Train is not the most supportive cross-trainer on the market.

Even with its pronounced midsole sidewalls on both sides of the heel, we felt like it allowed for too much inward rolling of the foot.

And while the underfoot platform itself felt stable for light-to-moderate strength training, the side-to-side support was lacking in this Nike trainer.

'An elastic band around the heel' doesn't sound particularly reassuring, and our manual test showed that it hardly contributes to the rearfoot stability or lockdown.

Being able to easily bend and squeeze the Flex Train's heel counter, we rated its stiffness at only 2 out of 5.

Gladly, the shoe's wide base helps to partially compensate for the lack of support in the upper. Based on our caliper measurements, the widest part of its forefoot platform exceeds the average at 116.3 mm.

The heel, on the other hand, is on par with the category average at 87.7 mm.

A thin synthetic toe rand offers little protection to the Flex Train's upper, and most of the shoe's mesh remains exposed to wear and tear.

But our Dremel test showed that the fabric has some decent abrasion resistance, scoring a moderate 3 out of 5 in toebox durability. So if you limit its use to the gym and non-abrasive surfaces only, it should last a good while.

Its internal mesh, on the other hand, showed even stronger resistance to our Dremel, scoring a high 4 out of 5!

And the outsole rubber didn't disappoint either, leaving a shallow 0.8 mm dent in our rigorous 18-second drilling session. Excellent result for a trainer under $100!

An outsole thickness of 3.2 mm also looked reassuring on our caliper, promising a solid lifespan.

The Flex Train's internal padding is moderate yet sufficient. We recorded an insole thickness of 3.4 mm, which is close to the category average.

The insole can be removed and replaced with an aftermarket insert for a more customized experience.

The tongue padding, on the other hand, is thinner than average at only 4.0 mm. This may not be enough to buffer lace bites if you lace them too tightly.

Some tongue shifting might be possible, too, as there are no gussets on its sides.

Pull tabs are not included in this Nike trainer.

The Nike Flex Train offers all the right basics for its low price and makes for a perfect budget-friendly training shoe.