Hummingbird Single Speed Flax review

Hummingbird first hit the headlines with its ultra-lightweight monocoque carbon-fibre Electric folding bike.

Now it’s taken that lightweight template and applied a new leaner, greener material in collaboration with the high-tech and high-performance motorsport firm, Prodrive.

Prodrive has built and raced cars for the likes of Subaru, Aston Martin and, more recently, for Sir Lewis Hamilton’s X44 team in the Extreme E Championship.

We first got a look at the Flax when it was our Bike of the Week back in September 2022.

Hummingbird Single Speed Flax build and spec details

The new material, which contains flax fibres, comes from the brand's research into sustainability to meet forthcoming stringent motorsport regulations.

Matt Bradney, Prodrive’s business development director, explains why flax ticks the boxes: “Most composites are still made with synthetic fibres, which are very energy consuming to produce, but natural fibres are grown, not made, so the energy requirements can be considerably less.

“Flax is the current predominant fibre in natural composites, with very good fibre and mechanical properties.”

Hummingbird claims that not only is the new flax composite used in the bike’s main structure lighter than the equivalent carbon fibre, it’s also better at reducing vibrations. So that makes this new model not only lighter than ever (it’s just 6.9kg) but a smoother ride too.

The bike, aside from its Flax main frame, has a truss-like CNC-machined alloy rear end that sits on a bushed pivot and is held in place by a simple quick-release.

The fork is made from carbon fibre and there are custom-made, tri-spoke carbon fibre wheels.

The bike is a singlespeed, and you can choose from either a 60-inch combination for easy pedalling, a middle ground of 65 inches, or the quickest option, with a 72-inch gear.

The rear sprocket spins on a splined freehub and engages very quickly. When freewheeling, it’s one of the most vocal around, with a wasp-like buzz that will do a good job of alerting people to your presence when you’re not pedalling.

The Shimano Alfine single-ring crankset is fine, but on a bike that costs nigh-on £4,000 I’d have expected something a little higher specced. The same is true of the brakes.

While the ultra-light CNC’d Aest brake levers are suitably swish, they’re operating Tektro’s R539 dual-pivot brakes, which are perfectly serviceable. However, I’d expect something a little slicker on a bike of this calibre.

On a more positive note, the carbon bar and seatpost, with titanium hardware, are both top-quality. The quick-release pedals are good too, and the rear end even has machined slots to store them in once the bike’s folded.

My test bike came with the optional extras of Brooks’ comfortable Cambium saddle and grips, both with hard-wearing yet soft elastic vulcanised rubber at their core.

Folding the bike is very easy. Simply undo the rear’s quick-release lever, sweep the back end of the bike under the front, drop the handlebars over to beside the wheels, and a custom hook on the end of the bar catches and holds the back wheel in place.

Then drop the seatpost and it all locks down. Slot the pedals into their holders (if you wish) and away you go.

The Hummingbird is much longer than a Brompton when folded (the Hummingbird folds to 177x60x20cm, compared to Brompton’s 65x60x32cm). However, it’s half a kilo lighter (the ultra-light titanium Brompton starts at 7.45kg, with prices from a similar £3,750).

Hummingbird Single Speed Flax ride impressions

The Hummingbird rides rather well: it’s very comfortable, even on the roughest roads with the fast-rolling Schwalbe Kojak slick tyres pumped up hard. The handling is swift and it’s easy to navigate through packed traffic at slow speeds.

You can lean into a corner and properly carve thanks to the frame shape, plus the high bottom bracket that gives plenty of clearance. The braking performance is good if a little lacking in feel at the lever.

The frame has a bit of flex, so it doesn’t respond well to big out-of-the-saddle efforts, but I can’t think of an electric folding bike that does. Make sure the rear end’s quick-release is tensioned up tightly because any play here can be amplified.

Hummingbird Single Speed Flax bottom line

I really like the Hummingbird and the brand's forward-thinking material choices. Flax may be a rarity right now, but I’d be interested to see if the tech can be applied to other bike parts and designs.

With a higher-end, lighter crankset and brakes, you’d drop a few more grams as well as improve the performance, which would make this bike even better.