Crankbrothers’ intentionally flexy rim-tech comes to entry-level alloy wheels

Front and rear "tuned", comfort-focused MTB wheels at a reasonable price

Crankbrothers has just launched a range of alloy-rimmed mountain bike wheels that have been designed to offer some of the compliance of its Synthesis carbon hoops but at a cheaper price point.


Wheels are available for enduro, XC/trail and e-bike applications, and they start from £500 a pair.

Crankbrothers Synthesis alloy wheelset
The Synthesis alloy wheelset claims front- and rear-specific compliance from £500. They look pretty smart too.
Immediate Media

What is Synthesis?

The carbon-rimmed Synthesis wheelset was launched back in 2018 and the idea behind the project was to combine the expertise and ideas of Jason Schiers, founder of ENVE composites, and Mello Bouwmeester, who pioneered supple single-wall carbon rims long before SRAM got in on the act.

Between them, they came up with the Synthesis concept, which blends together ideas from the two engineers’ backgrounds.

Their creation combines a stiff rear wheel, for snappy cornering, with a flexier front wheel to reduce harshness transmitted to the hands.

They achieved this contrasting feel partly with a higher spoke count on the rear wheel than the front (32 spokes and 28 respectively), and the use of different rims with distinct carbon-layups.

The front rim is not only less stiff, it’s also lighter, shallower in profile and slightly wider.

Crankbrothers Synthesis alloy wheelset pricing

The carbon versions don’t come cheap; a top-line E11 wheelset with Industry-9 hubs and bladed spokes costs £2,150, while a Synthesis E wheelset with Crankbrothers’ own hubs and heavier spokes costs £1,500. That’s where these latest alloy wheels come in.

The new wheels are available in three versions, designed for enduro, XC/Trail (XCT) and e-bike use. The enduro and XCT wheels both cost £500 with Crankbrothers’ standard hub, or £700 a pair with the I9 hubs. That’s £1,000 and £1,450 less than the carbon equivalent, respectively.

The e- bike wheelset is only available with the Crankbrothers hub and costs a little more at £540 a pair.


  • Wheelsize options: 27.5 Boost / 29 Boost
  • Hub options: Crankbrothers Synthesis (17-degree engagement) or I9 101 hub (4-degree engagement)
  • Price with Crankbrothers Synthesis hub: £199.99 / $239 / €239 front and £299.99 / $359 / €359 rear (wheels sold separately)
  • Price with I9 101 hub: £264.99 / $299 / €299 front and £434.99 / $499 / €499 rear (wheels sold separately)


  • Wheelsize options: 27.5+ Boost / 29 Boost
  • Hub options: Crankbrothers Synthesis only
  • Price: £214.99 / $259 / €259 front and £324.99 / $389 / €389 rear (wheels sold separately)


  • Wheelsize options: 29 Boost only
  • Hub options: Crankbrothers synthesis (17-degree engagement) / I9 101 hub (4-degree engagement)
  • Price with Crankbrothers Synthesis hub: £199.99 / $239 / €239 front and £299.99 / $359 / €359 rear (wheels sold separately)
  • Price with I9 101 hub: £264.99 / $299 / €299 front and £434.99 / $499 / €499 rear (wheels sold separately)
  • Enduro and XCT rims are available separately at £99.99 each.

Crankbrothers Synthesis alloy wheelset details

Crankbrothers Synthesis alloy with tyre
You’d be hard pressed to spot the difference between the alloy and carbon rims on the trail.

The alloy Synthesis rim looks strikingly similar to the carbon version, except that it has a hooked rim bead instead of the hookless carbon rim.

The carbon rim also has a much wider rim sidewall than the alloy wheels; wider sidewalls can, at least in theory, reduce the risk of punctures by spreading the load over a wider area.

The inner rim width is the same as the carbon version though.

Crankbrothers Synthesis alloy rims
Look closely and you can see the front rim (right) is slightly wider than the rear.

The Synthesis alloy, like the carbon version, uses different rims front and rear. The rear is designed to be stronger to resist impact damage, and the front rim is wider to provide a little more cornering bite by squaring up the tyre, while keeping the rear tyre rounder for better rolling speed.

The enduro version of the alloy wheels have an inner width of 31.5mm front and 29.5mm rear. They use 28 Sapim D-Light spokes in the front and 32 Sapim Race spokes in the rear. They’re available in 27.5in or 29in wheel sizes.

The XCT wheels have 26.5mm front and 24.5mm rear inner rim widths. They too use a 32 front/28 rear spoke count, but have Sapim D-Light spokes at both ends. They’re available in 29in only.

The e-bike wheelset has 31.5mm inner rim width front and rear. Spoke count is again 28/32, but with beefier Sapim E-light spokes up front and Sapim strong spokes in the rear. They’re available in 27.5in or 29in wheel sizes.

There is a 27.5+ option for the e-bike wheels, with 35.5mm-wide rims front and rear. These are available in 27.5in only.

All Synthesis alloy wheels are sold individually, so it’s possible to mix and match between wheel sizes.

All the above options are available in Boost only and can be supplied with HG, SRAM XD and Shimano Microspline freehubs.

The main difference between the Crankbrothers and Industry-9 hubs (other than price) is the engagement angle. I9 offers a fast 4-degree engagement angle (with 90 points of engagement in the freehub) and the Crankbrothers a fairly slow 17-degree angle (21 points of engagement).

So, when you start pedalling, there will be considerably less dead stroke in the crank with the I9 hubs before the freehub engages the wheel.

There is a small difference in weight too.

Crankbrothers Synthesis alloy wheelset weight

We’ve been sent two sets of the enduro wheels: one with the Crankbrothers hubs and one with the I9 hubs, both 29in and with SRAM XD drivers.

On the BikeRadar scales of truth, they weigh 2,116g and 2,027g respectively. Not exactly light, but not heavy either.

By comparison, the carbon Synthesis Enduro wheelset with I9 hubs (also in 29in and with XD driver) weighs 1,889g on our scales.

So the alloy wheels weigh 138g more than the equivalent carbon set. Considering they cost £1,450 less, that’s probably a weight penalty worth swallowing for most.

What’s the bottom line?

Of course, the proof is in the riding. Will the alloy rim sacrifice the supposed compliance benefits of the original Synthesis wheelset?

In our experience, alloy wheels generally offer superior ride quality and vibration damping in rough terrain. The reasonable price, particularly with the Crankbrothers hubs, could make them a compelling option for those who want a smart-looking enduro wheelset but don’t want to break the bank.


We’ll report back with a review in due course.