Bontrager XXX Carbon £470

Clever adjustable-length cranks with great rings

BikeRadar score 4/5

Bontrager's Race XXX Lite Carbon crankset is impressively light and has stayed secure despite a year of very hard use.

The Stronglight CT2 chainrings are excellent too, with instant shifts and great longevity. The arms have stainless steel skid plates on the ends and down the centre to shrug off damage. The recommended Stronglight Twister SL BB has lasted well too, despite permanently filthy, zeroicare use. The price is definitely bordering on excessive though.

The nitty-gritty details

Keith Bontrager doesn’t like to be told how bike components should be designed, but by the same token he won’t ignore good ideas when they’re offered.

It’s why the top-of-the-range Bontrager XXX carbon fibre crankset uses many technologies and ideas from French brand Stronglight. It’s a quirky outfit, whose products are highly respected in the world of Audax riding (extremely long point-to-point reliability rides). In recent years they’ve worked hard to get into the mountain bike market, and in doing so have developed several new technologies which they use on their own cranks and chain rings. It is Stronglight’s ‘out of the box’ thinking that attracted the attention of Mr Bontrager.

One example of clever thinking on the Bontrager XXX is the ALS (adjustable length system) which allows the same crank arms to be run at either 170mm or 175mm lengths. This is achieved using a crushingly simple alloy wedge which houses the threaded pedal hole. All you need to do is take the pedal out, turn the wedge the other way up and re-fit the pedal. Once you’ve got the length dialled, that’s the end of the tech.

The Stronglight CT2 chainrings are some of the best we’ve ever used. The alloy rings have a hard Teflon-impregnated ceramic coating, which both extends the service life of the rings and also makes them extremely slippery. The reduction of friction between the chain and chainrings may seem like a small thing, but once you get the cranks spinning you can really sense the rings almost ‘spitting’ the chain off as you pedal.

We expect the CT2 rings on our Bontrager XXX to last a long time, too – we’ve had a set on the go on our Magma crank for nearly three years on a full-suss XC race bike and the coating is only just wearing out.

Perhaps the standout feature of the Stronglight crank concept is the company’s championing of the ISIS bottom bracket (BB) standard. The early ISIS bottom brackets had poor life expectancy, but those from Stronglight, Crank Brothers and FSA are solid and dependable. The Bonty XXX uses the ISIS BB, too – unusual in these days of external BB and integrated BB axles. We used an FSA Platinum Pro Ti ISIS BB to test the Bontrager XXXs and they spun beautifully. In terms of outright stiffness, they feel on a par with the best cranks from FSA and Shimano.

Two nice touches are the stainless steel scuffplates on the outside edge of each crank and (optional) stainless steel covers to protect the ends of the carbon crank arms. These add little in terms of weight, but stop them looking battle-scarred after the first mud ride.

All up, we love the way the XXX works; we like the understated look, and we appreciate the extra effort that has gone into making this a crankset that’ll keep on looking and working the same way in a year’s time as it does now. You're definitely paying for the priivilege, though.

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