BH Ultralight Dura-Ace Di2

Super lightweight performance racer

BikeRadar score4/5

Hailing from the Basque Country, the BH Ultralight lives up to its name in every way. Tipping the scales at 6.33kg (13.93lb), the Dura-Ace Di2 equipped Spanish bike comes in well beneath the UCI mandated 6.8kg.

For those not racing on the WorldTour, though, this BH offers aggressive geometry that delivers a snappy and stiff – yet compliant – ride with exceptional road feel.

Ride and handling: nimble and explosive

The Ultralight is extremely nimble and requires very little input going into a corner, yet never feels nervous or unmanageable even at high speed. A stiff carbon fork with 1.5in tapered steerer tube combined with a 150mm carbon head tube makes for a rigid front triangle, which is partly responsible for the sharp handling.  

Whether you're on a steep climb or sprinting for a road sign it takes nothing to whip the Ultralight back and forth. Sometimes with super light bikes stiffness is sacrificed in the name of shaving grams, but with the BH that is not the case – there's no discernible flex or loss of power.

A massive PressFit 386 EVO bottom bracket creates plenty of real estate for the huge down tube and seat tube to converge upon. The mass of material at the cranks and beefy chainstays transfer every watt you put in to the back wheel. This combined with a Shimano Dura-Ace C24 wheelset makes for an explosive reaction when attacking the pedals. The Ultralight is tailor made for changes in speed, both on low speed climbs and high speed sprints.

An external Di2 battery is mounted on a beefy chain stay behind a massive bottom bracket shell

Despite the unyielding front end, solid pedalling platform and questionable 22c rubber (on our Australian-spec machine), the BH is surprisingly comfortable. The carbon monocoque frame and thin seatstays enable the frame to soak up both high frequency road buzz and – to a lesser extent – larger impacts.

Unfortunately that compliance doesn't extend to the seating arrangements. Our Australian model came with a full carbon Prologo Zero2 saddle, which we found extremely uncomfortable. One of our testers' strict diet of donuts and cake had created a bit of extra 'natural padding', but even he could only manage about two hours on the Zero2 before it became unbearable.

The full carbon saddle is pretty unforgiving

Frame and equipment: questionable weight saving in some places, and a lack thereof elsewhere

BH uses its 'core removal technology' carbon moulding process for the Ultralight. It's claimed the high pressure system enables the engineers to control carbon thickness throughout the frame in order to achieve the "best possible compaction". This means the thickness of the tubes is adjusted to create an optimal stiffness to weight ratio.

BH says this system removes inconsistent pressure within the mould, eliminating potential imperfections and bubbles in the carbon and reducing the need for post-mould finishing work.

Few will know what you're riding with the stealthy graphics

As mentioned above, the Ultralight is – like previous models – based around a PressFit 386 EVO bottom bracket. The large 86.5mm bottom bracket shell offers great crank compatibility options and provides extra space for larger tube shapes to converge.

Our size medium sample had a long 55.7cm effective top tube, providing an aggressive, stretched out position. The semi sloping geometry, slightly raised head tube, short rear triangle, and 72 degree seat angle created a lower centre of gravity; which translates into razor sharp handling and the Ultralight’s affinity for changes in pace.

The sloping top tube of the Ultralight

Since we last tested the Ultralight, BH has switched from external to internally routed cables, allowing for both mechanical and electronic groupsets and helping to keep wires and cables out of harm's way.

Our sample rig came equipped with a top-end Shimano Dura-Ace Di2 groupset. It's shifting prowess is well-established: a quick press of a button is followed by an instantaneous and precise change.

The best part however is the sure-shifting front derailleur, which not only self-trims to eliminate chain rub, but also provides for a perfect shift every time. A semi-compact 52/36T crankset up front and 11-25T cluster on the rear, combined with the meagre 6.33kg weight, helped us to float up steep gradients with minimal effort.

The Dura-Ace C-24 wheels add to the quick handling of the Ultralight

Low profile Shimano Dura-Ace C24 wheels only add to the Ultralight's ability for rapid pace changes. Even with an aluminium brake track, these stiff, explosive carbon clinchers still only tip the scales at 1410g.

While the C24's are a solid set of daily hoops – they spin up extremely fast and further contribute to the BH’s sharp handling – the addition of some lightweight full carbon race wheels is a mouthwatering prospect.

We'd have to say though, that some of the fat-trimming techniques BH Australia has employed to create this weight weenies' delight are questionable. That unforgiving carbon Prologo seat and the 22c Vittoria Diamante Pro Radiale tyres have little benefit beyond influencing numbers displayed on the scale. 

22c tyres are a questionable choice

The Ultralight is a million miles from being a cheap bike, yet swapping saddles and tyres is something many will do from the get-go. The San Marco Aspide Carbon FX saddle and 25c Michelin Pro4 Service Course rubber we used for the second half of this test only added 37g to the total weight.

For this kind of money, we'd also like to see an internal battery given despite its late-season arrival (the release date has prompted BH to opt for the heavier external Di2 powerpack). Additionally, while those C24 wheels are nice, they're not especially light nor aerodynamic, leaving another expense waiting if you're seeking ultimate speed.

Bottom line: close to perfection

BH has found an ideal combination of stiffness and comfort

The BH Ultralight Dura-Ace Di2 is an almost flawless ride: it’s fast, stiff, light and surprisingly comfortable. Only the small oversights involving the saddle, tyres and Di2 battery hold it back from a perfect score.

The exact build of the BH Ultralight Dura-Ace Di2 varies in different countries, but the frame, fork and many of the components are the same. The full UK spec can be seen here.

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