Verdict from 9.4 hours of research from the internet

5 reasons to buy

  • Many customers described the Newton Sir Isaac S as comfortable.
  • The midsole has provided fantastic support and cushioning, according to several wearers.
  • A couple of users reported that the pains on their knees and shins were gone after using the Sir Isaac S.
  • The shoe gave an excellent performance during races, as experienced by a runner.
  • A lot of users expressed that the shoe felt great even when worn right out of the box.

1 reasons not to buy

  • Some wearers thought the Sir Isaac S was slightly heavy.

Bottom line

Majority of the users were welcoming and happy about the comeback of the Newton Sir Isaac S. Numerous commenters stated they have purchased more than one pair because of how efficient their running is with the shoe. While some were not a fan of the shoe’s weight, its comfort level and supportive quality were more significant.

Tip: see the best running shoes.

Expert reviews:

  • The Sir Isaac S was a previously released shoe from Newton, which the brand is now bringing back due to popular demand. This time around, the shoe has been made more structured and more supportive than before, giving overpronators a stable and cushioned ride.
  • The upper retains the usage of the closed mesh material and slip-proof laces, but now has an added lightweight support strapping for ergonomic purposes. Like all other Newton shoes, the Sir Isaac S is cruelty-free and is made from vegan materials.
  • While the sole unit mostly has a similar structure as the original version, the new Sir Isaac S has a slightly higher heel-to-toe drop of 4.5 mm. The outsole introduces a heel rocker that produces an enhanced toe spring.

The Sir Isaac S from Newton has a standard running shoe length, and it comes in a wide range of size options. The shoe stays close to the construction of other Newton shoes, with its moderate midfoot and heel sections that will comfortably accommodate low to medium foot volumes. The Newton Sir Isaac S is available in medium width for both the men’s and women’s versions.

A high-wear carbon rubber makes up the bulk of the outsole of the Sir Isaac S. This material is known to be durable; hence, it guarantees the underfoot a robust protection that would not deteriorate quickly.

A set of high-traction lugs deliver the adequate grip to ensure a smooth ride and hassle-free running experience for the wearer.

The outsole also has a rocker structure that enables a motion that is similar to a rocking chair; this means mobility is natural as possible while also allowing an efficient transition.

The Newton Sir Isaac S utilizes an ethylene-vinyl acetate (EVA) foam midsole that possesses the brand’s proprietary Action/Reaction™ technology. Working in the midfoot and heel areas, this feature creates a responsive system that is like a trampoline. The movement of the lugs in the outsole causes a quicker bounce-back. The Action/Reaction™ technology also reduces the amount of energy loss compared to traditional foams.

Because the Sir Isaac S is a stability shoe, the midsole incorporates a midfoot support chassis to keep the foot stable while running. This detail also retains and preserves the structure of the shoe by acting as a framework.

A medial post is also present, a piece of foam firmer than the midsole itself, that runs from the midfoot to the forefoot. This medial post ensures the runner keeps a steady stance, and, in turn, reduces overpronation.

The highly-breathable closed mesh upper of the Newton Sir Isaac S promises maximum airflow inside and around the shoe. Its unique composition also assures the coverage the foot needs.

The shoe’s overlay system has the same layout as the original version. While it offers reinforcement and structural integrity, it also acts as the “eyelets” as the laces pass through, therefore allowing more or less support depending on how tight the laces are tied.

The shoelaces still have the slip-proof feature, which means they don’t unravel as quickly as standard laces.

A set of metatarsal stretch panels is found in the forefoot section of the Sir Isaac S. These elements prevent irritation and give more space, so the foot could move freely.

The Sir Isaac S also has a lightweight, ergonomic support strapping, which provides ample support and security during the running activity.

For low-light visibility, the shoe includes a reflective printed logo and heel tab.

Size and fit

True to size based on 14 user votes
Small (7%)
True to size (93%)
Large (0%)
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How Sir Isaac S compares

This shoe: 83
All shoes average: 86
53 98
This shoe: $150
All shoes average: $119
$40 $350
This shoe: 11.6oz
All shoes average: 9.5oz
3.5oz 16.2oz
Jens Jakob Andersen
Jens Jakob Andersen

Jens Jakob is a fan of short distances with a 5K PR at 15:58 minutes. Based on 35 million race results, he's among the fastest 0.2% runners. Jens Jakob previously owned a running store, when he was also a competitive runner. His work is regularly featured in The New York Times, Washington Post, BBC and the likes as well as peer-reviewed journals. Finally, he has been a guest on +30 podcasts on running.