Middleburn RS-8 ISIS Duo 29/42 Chainset review

Versatile, classic CNC-machined chainset

Our rating 
4.0 out of 5 star rating 4.0
GBP £185.00 RRP
Middleburn RS-8 Chainset

Our review

Versatility makes this stiff crankset a high-value option
Skip to view product specifications

Lighter spinners will love the low weight of Middleburn’s RS-8 ISIS Duo chainset. Stronger riders will feel a lot of flex in the spindly outer ring, and shifting isn’t quite as slick as a triple set-up.


You can also swap the spider for a triple or a single ring if you want, making this a uniquely versatile, high-value set-up.

The fluidly sculpted RS8 arms are impressively stiff, and come in square taper or ISIS splined versions. We used a £100 titanium-axled Stronglight ISIS Twister SL bottom bracket to keep weight low and durability high, but SKF make good ISIS units now, too.

The outer rings come in silver, black, red, blue or hardwearing ‘Hardcote’ options, and a 40/28 tooth option is due soon.


Some of you might not be familiar with British brand Middleburn, but these Hampshire-based engineers have been making superb-quality CNC machined cranks and other components for nearly 20 years.

Product Specifications


Name RS-8 ISIS Duo 29/42
Brand Middleburn

Manufacturer's Description Machined from the same billet as the RS7 but with more weight reduction to reduce mass but retain stiffness.
Weight (g) 722
Features Available in ISIS or square-taper interfaces. 175mm length only. Perfect for XC racing and trail riding.
Bottom Bracket Included No
Chainring Set-up Double
Bottom Bracket Type Square
Chainring Options Double