Adizero Boston 12 vs Adizero Boston 13

The Boston 12 is where adidas fixed the Boston. Versions 10 and 11 had a reputation for a hard, brick-like midsole, and reviewers mostly agreed this one rides softer and livelier while keeping the snap that makes it a tempo running shoe. On paper it's 267g with a 7mm drop and fibreglass rods rather than a carbon plate, so think of it as a training partner for faster sessions and marathon-block long runs, though one reviewer reckoned it could double as a budget racer. Women's Running UK gave it four stars, and Runnea's reviewer picked out how stable it stays on long runs. Where it falls down is fit: a thin tongue, laces that slip and a soft heel counter that heel strikers may not trust. Adidas has since released the Boston 13, which keeps a similar ride and pads the heel and tongue. So the 12 makes most sense when it's clearly the cheaper of the two.

Adidas left the Boston 13's ride close to version 12 and put most of the update into comfort, with a padded heel and tongue and a new mesh upper. There's also more Lightstrike Pro sitting above the stiff carbon-infused rods. It's still a firm tempo shoe that's happiest once the pace picks up, and at £140 it's a cheaper way into rod-assisted speed than a proper carbon racing shoe. Its biggest rival is another adidas. Ben Parkes and Fordy Runs both liked the Boston 13, and both reckoned most runners would have more fun in the lighter, softer Adizero Evo SL. The Boston's argument is durability and a steadier platform, so we'd point it at runners who want one hard-wearing pair for workouts and marathon-block long runs. If you already own a Boston 12 you get on with, the changes are small.