Crankbrothers Synthesis E 11 is a carbon wheelset of impressive quality, with top-class Industry Nine hubs, position-specific rims and unique builds for each end. It’s hard to fault these impressively robust hoops for concept and quality, although the difference in compliance between front and rear is hard to feel – and the price is top dollar.
These wheels actually come from a collaboration between Crankbrothers and two carbon specialists. The first, Jason Schiers, is known for starting Enve and creating incredibly stiff wheels, while the second – the fantastically named Mello Bouwmeester – is known for single-walled carbon rims with compliance. So it shouldn't surprise you the resulting Synthesis E 11 aims to nail carbon's ability to combine both stiffness and flex.
Nevertheless, the 'synthesis' moniker actually refers to the variation between front and rear wheels. In effect, you get a compliant front wheel for increased damping and a more constant contact patch, allied to a stiff rear wheel that's built for responsiveness at speed. At least, that's the theory.
The differences are mostly easy to see. The front rim is lighter than the rear yet has a larger inner diameter (31.5mm against 29.5mm), plus it uses fewer spokes (28 against 32) of a thinner gauge (they're Sapim CX-Ray instead of CX-Sprint) strung with a lower tension.
The rear rim is built tougher, heavier and is 0.5mm thicker at the bead too. Crankbrothers have shaped the whole lot to work best with 2.35-2.5in tyres.
I’ve put a good eight months of use into this set on my longterm test bikes, most recently on a carbon Specialized Stumpjumper. I use mostly 2.6in Specialized tyres, swapping between a Butcher and a Hillbilly (conditions dependent), either with Grid or the tougher BLK DMND casing on the rear.
Getting tyres onto the rims is relatively easy, with very little of the struggle you get when trying to seat tubeless tyres on some cheaper carbon rims. No, its not as easy as some alloy/rubber combinations, but I never worried about dealing with a puncture on a ride and having it take forever (or taking the skin from my fingers).
I also fitted Cushcore in the latter stages of testing, which went on noticeably easily too – my feeling is the high quality and accuracy in the thickness of these carbon rims is the reason they're so easy to use. They're certainly easier to live with than other, cheaper carbon wheelsets I've run.
At first I rode the Synthesis wheels tubeless and without tyre inserts. Hitting rough sections could induce noticeable chatter and loss of traction – predominantly from the rear wheel – that required a concentrated digging in of heels to counter.
This was the only setup in which I felt a difference between front and rear wheel. Even so, I think there are too many variables to draw a definitive conclusion on the relative compliances... tyre choice, casing and pressures all play a part. The difference between wheels, for mere mortals, is quite slight.
What I definitely notice is the slightly wider front rim giving a great profile to my 2.6in tyre (the Hillbilly measures up pretty true to its claimed width, so there's a little latitude in the official size recommendations).
My first set of test wheels came with hubs from Project 321, but branded as Crankbrothers. About six months in the front hub developed noticable play, so distributor Extra UK sent a replacement set. These new rims came with Industry Nine Hydra hubs.
Extra cited the reason behind the change as an inability to develop quickly enough with Project 321. It seems prudent, if you're looking to invest in a set of these, to make sure they come specced with the 'i9' hub as opposed to 'P321'.
The six-pawl i9 hubs are something special. With 690 points of engagement and 0.52º degrees of rotation between points, the pick up is super quick and the power transfer very efficient. Oh, and and the buzz they produce is seriously cool...
The Project 321 hubs were good (while they lasted) but the i9 hubs are better, with even sweeter pick up and, we hope, better durability. It’s worth noting that I haven’t been able to put in the same length of test time into the i9 hubs, but if a problem occurs this review will be updated.
Switching from plain old tubeless to Cushcore, the ride was transformed – showing that it is, indeed, possible for a mountain bike wheel to be too stiff and too light. Basically, the Cushcore insert dampened vibrations and let me run both lighter tyre casings and lower pressures, and the result was greater traction.
Like our editor here on off-road.cc, I find carbon rims can produce a harsh ride. Sure, the feel is stiff and precise, but take a wrong line and they can pinball, with the bike deflecting from obstacle to obstacle. The Synthesis E 11s, gorgeous as they are, did nothing to convince me otherwise, especially post-Cushcore experiments.
With the extra damping the E 11s are excellent and, I think, one of the best improvements I’ve made to my bike recently. But do you really want to be spending £160 on tyre inserts after dropping £2150 on wheels?
At 1760g for the pair, this wheelset is not superlight, but about right for a tough set of enduro-ready rims. The 29ers are a tad heavier at 1825g – to put this into perspective the ENVE M735 designed for similar use with the same hubs are a claimed 1895g.
Crankbothers offers a lifetime warranty on the rims so long as you register the wheelset, but we doubt you’ll be using it once registered. I’ve not dented or even scratched the rims I tested, and I lent them to some of our heavier riders as well, just to see if they had any issues – they didn’t, and I’ve not even touched a spoke.
The i9 hubs get a two-year warranty, but note that neither warranty is transferable from from the first owner if you're looking to buy used.
These wheels are available in either this top-end Synthesis E 11 spec or as the £1,500 Synthesis E, which use Crankbrothers hubs and Sapim D-Light/Race spokes on the same rims. There are further variants for downhill (DH) and cross-country/trail (XCT) to go alongside these enduro (E) versions.
Of course, if you already have a decent set of hubs you can go rim-only for £599 a hoop. Then you'll just need to factor in the cost of spokes and someone to build it for you. Bargain. If you're racing though, and truly appreciate the precise nature and exceptional quality of a wheelset such as this, then the positives will no doubt outweigh the negatives.
If you can stomach the price tag, Crankbrothers' Synthesis E11s – with i9 hubs – are a seriously well-built, extremely responsive and lovely-looking addition to any bike. They don't solve the fundamental issues with carbon's willingness to shake rather than shimmy through the rocks, but if that doesn't bother you, you're unlikely to do anything but love the Synthesis E 11s.
You might also like: