Wheels are one of the most important components on mountain bikes, and e-MTBs in particular are subject to enormous forces. With the Synthesis series, Crankbrothers has developed a special approach that aims to find the perfect balance of grip, control, and stability with unequal front and rear wheels. We put the new Synthesis Alloy 2.0 e-MTB wheelset in the top version with Industry Nine hubs through its paces for a season to find out if the concept works in practice.
The Synthesis concept: flexible at the front, stiff at the rear
Anyone looking at Crankbrothers' wheels will quickly notice: the front and rear wheels are not identical. There's a clear philosophy behind this approach, which the manufacturer calls the "Synthesis Tuned Wheel System." The front wheel is designed to provide maximum grip and control in corners while absorbing bumps. It is therefore deliberately designed to be "softer," or more compliant. This is achieved by a smaller number of spokes—in this case, 28—and a wider rim with a 31 mm inner width. The larger volume is intended to allow the tire to better adapt to the surface and increase traction.
The rear wheel, on the other hand, is engineered for stability and precision at high speeds. Designed as a "stiff" counterpart to the front wheel, it must absorb the main loads and the drive forces of the motor. Crankbrothers uses 32 spokes and a slightly narrower rim with a 29,5 mm inner width. This design is intended to ensure better tracking and prevent the wheel from flexing sideways under load.
What's new in version 2.0?
With the second generation of its aluminum wheels, Crankbrothers has made some crucial adjustments, primarily to improve durability. The rims are now made from a 6069 aluminum alloy, which, according to the manufacturer, offers significantly higher tensile and yield strength than its predecessor.
Additionally, the rims receive a "shot peen" finish. This process involves bombarding the surface with small particles, which strengthens the material and makes it more resistant to cracking. The result is a matte, robust appearance that also increases durability. Another important update is the new, wider rim profile with reinforced sidewalls. This design aims to reduce the dreaded "pinch flats" (the tire being crushed between the rim and an obstacle) and further increase impact resistance in the event of a puncture.
Crankbrothers is so confident in the robustness of the new rims that they offer a lifetime warranty.
Two hubs to choose from
The Synthesis Alloy 2.0 wheels are available with two different hub options. The more affordable version features the company's own "CB Ratchet" hub with a solid 10-degree engagement angle. The top-of-the-line version we tested, however, comes with the high-quality Industry Nine 1/1 hubs. These USA-made hubs are known for their durability and fast engagement. With a very low engagement angle of just 4 degrees, they promise virtually instantaneous power transfer.
The Crankbrothers Synthesis Alloy 2.0 E-MTB wheels in the field test
For the test, we mounted the e-MTB version with I9 hubs in a mullet configuration (29 inches front, 27,5 inches rear) with an XD freehub on an e-enduro bike with 170 mm of travel – a true endurance test scenario. The wheels had to prove themselves over an entire season: on our home trails, in bike parks like the Geißkopf, and on the challenging routes in alpine regions like Vinschgau and Finale Ligure.
The weight we reweighed was 1.071 grams for the front wheel and 1.154 grams for the rear wheel. This is a decent, albeit not record-breaking, value for a sturdy aluminum e-MTB wheelset. Durability is clearly the top priority here. The price of just under €900 for the set is reasonable, considering the generous warranty and the expensive I9 hubs.
Unobtrusive in the best sense
The wheelset's character quickly became apparent on the trail: it's unobtrusive in the truest sense of the word. From day one, the wheels performed flawlessly and reliably. The interplay between the high-traction front wheel and the stiff rear wheel provides a great deal of confidence. The bike steers precisely in corners without seeming nervous, and on fast, rough sections, the rear stays stoically on track.
The robustness was particularly impressive. Despite several severe punctures, which we expected to result in a puncture or a dent in the rim, the rims proved completely unaffected. Even at the end of the long test period, spoke tension was still excellent, and the wheels ran smoothly without any noticeable radial or lateral runout.
The Industry Nine 1/1 hubs: Quiet and lightning fast
The Industry Nine 1/1 hubs deserve special praise. Compared to the more well-known and significantly louder Hydra hubs from the same manufacturer, the 1/1's freehub is pleasantly quiet. However, the extremely fast engagement with just 4 degrees of engagement angle is a clear advantage, especially noticeable on technical climbs. If you need to pedal quickly to clear a step or adjust your pedal position, the hub engages immediately and without any noticeable play. This ensures control and efficiency on challenging terrain.
