Verdict from 6 experts and 49 user reviews

6 reasons to buy

  • The closed mesh upper offers breathable coverage that also keeps debris at bay.
  • The sporty design has been welcomed by many reviewers.
  • The Single-density, high-rebound EVA cushions the foot while providing moderate stability.
  • The testers have also noticed the inclusion of a mid-foot chassis/shank, which heightens the stability given by the Sir Isaac.
  • The Action/Reaction Technology found in the forefoot area absorbs impact energy, then boosts the propelling motion of every step.
  • Beveled lugs in the outsole usher the runner through a more responsive running experience.

3 reasons not to buy

  • Some runners noticed the outsole breaking its integrity after a few months of use.
  • Others thought that it was a bit too wide in the forefoot area.
  • A few noted that it looked a bit bulky.

Bottom line

The Sir Isaac from Newton is a daily running shoe that functions well in many kinds of activities. It is a solid offering to runners who want underfoot support, a breathable upper, and a responsive outsole. Overall, the Sir Isaac running shoe proved to be a desirable choice for a simple, no-frills runner.

Tip: see the best running shoes.

Good to know

  • The Newton Sir Isaac is a training shoe that features systems and components that offer pronation support. Performance-wise, this shoe delivers because it keeps the runner moving forward in a well-guided way. Beveled lugs give a springy and more enabled lift, especially when tackling the forefoot lifts. This is a reliable shoe to take to the roads.
  • The upper unit of this Newton shoe uses durable yet comfortable materials to make sure that the runner feels safe and secure. A closed construction is intended to keep small debris out, but it’s still very breathable. Stitched-on overlays make sure that the fit is more customizable and responsive to the adjustments made to the lacing system.
  • The mid-sole unit features systems and platform technologies that ensure the foot is comfortable and well-supported at all times. A high-rebound foam gives bounciness with each step, while the support chassis adds stability to the stance of the foot.
  • A carbon rubber outsole keeps the sole unit protected from the abrasive nature of the asphalt. The Action/Reaction™ technology moves the platform like a trampoline that propels the runner upward for a smoother and more enabled stepping motion.

The Newton Sir Isaac has a regular running shoe length. The sizes that are available for men and women follow the standard measurements. The heel, mid-foot and forefoot sections have medium widths, so this shoe accommodates the runner who has a medium sized foot. Its semi-curved shape allows the wearer to acclimate well to it.

Carbon Rubber is a strong compound that’s used for the outsole unit of the Newton Sir Isaac. It is placed in critical sections where wear and abrasion are most likely to happen. It also gives effective traction over the roads, giving the runner dependable surface control.

Beveled Lugs are placed in the external sole unit. They guide the foot towards a smoother and springier performance. They also allow a stable feel in the forefoot section.

The Action/Reaction™ Technology is applied to the surface lugs of this shoe. It causes these units to absorb energy and give it to the runner, essentially enabling a more propelled and boosted lift of the foot.

A single-density, high-rebound EVA serves as the main platform on which to rest the foot. It is very responsive and it even adds a bit of bounciness to the underfoot experience. It doesn’t wear off easily, so it stays efficient even after many uses.

A Midfoot/rear support chassis allow the foot to be more stable when running. It balances the foot and guides it to a more effective and stable ride.

The upper unit uses a closed mesh material. Though it has a closed construction, it still encourages air to enter the shoe and keep the foot cool & dry. It also prevents any debris from entering the shoe, thus keeping the interior clean and free from any hazards.

The Enhanced Sock Liner adds more cushioning to the wearer. It also has a mildly bouncy nature, so energy is given back to the foot for more energized performance all throughout.

The overlay system has been stitched onto the upper unit. They allow a more customizable fit because they cause the upper unit to follow with the tightening and loosening of the shoelaces.


How Newton Sir Isaac ranks compared to all other shoes
Bottom 44% road running shoes
All road running shoes
Bottom 16% Newton running shoes
All Newton running shoes
Bottom 45% neutral running shoes
All neutral running shoes


The current trend of Newton Sir Isaac.
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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.