Crankbrothers Synthesis E I9 alloy wheelset review

Now available with more affordable alloy rims, Crankbrothers’ Synthesis wheelsets combine a stiffer, stronger rear wheel with a lighter, more flexible front wheel.

• Best mountain bike wheels
• Best mountain bike tyres

The idea is to maintain precise cornering and reliability while improving front-end comfort. The front wheel uses a lighter rim that has a slightly broader 31.5mm inner width to improve cornering bite, while the rear wheel uses a tougher but narrower 29.5mm rim to reduce rolling resistance, by rounding-off the tyre.

There are 28 Sapim D-Light spokes at the front and 32 Sapim Race spokes at the rear, further increasing the strength/stiffness disparity.

You get the choice of Crankbrothers or Industry Nine hubs. Other than the price (£500 and £700 a pair, respectively), the main difference is the pick-up speed.

The I9 hub offers a fast 4-degree engagement angle, while the Crankbros hubs have a slow 17-degree angle. There’s a small weight difference too – on our scales, the wheels weigh 2,116g with Crankbrothers hubs and 2,027g with I9 hubs (both 29in, with SRAM XD freehubs). For comparison, the equivalent Synthesis carbon wheelset weighs 138g less but costs £1,450 more!

Installing Maxxis EXO-casing tyres tubeless was more difficult than usual without resorting to a compressed-air inflator. Not a big problem, but worth being aware of.

I also noticed some spoke noise when sprinting in low gears at first, suggesting that the wheels weren’t adequately stressed prior to being ridden. After a few hard rides, but no major impacts, the rear wheel is out of true by about 2mm.

Again, no big issue, but not ideal. On the plus side, both rims remain dent-free and the I9 freehub still works like new, with a nice, subtle coasting whir.

The E 19s are silent when rattling through rocks, and while differences in ride feel between enduro wheels are subtle at best, they’re among the comfiest I've tried when it comes to minimising hand pain over harsh trail chatter.

The downside is a touch more lateral give when you stuff the front wheel into a rocky berm, but this too is barely noticeable and not necessarily a bad thing.

Weight is respectable for the price. You can get slightly lighter for similar money, but won’t notice any benefit. Just as important to some, they look smart.

The £500 set in particular looks far more premium than other wheels in that price category, and even this I9 set-up undercuts many premium alloy rivals while offering a touch more hand comfort.

• Front £265 / $299 / AU$640
• Rear £435 / $499 / AU$995