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Tech-Redux: BH Ultralight

From issue 13

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The BH Ultralight is a Spanish bike, or more accurately a Basque bike. The headquarters of BH are in the capital of the Basque country and have been since 1909. The first bike to win the Vuelta, BH sponsors the Spanish national team and multiple professional Spanish road teams. So why, you may be asking, is the BH Ultralight in an issue dedicated to French cycling?

The new Ultralight, BH’s brass-ring racer, their power-to-weight ratio, cost-is-no-object top-tier machine, has a French mistress. While test jigs and German labs get a lot of play in advertising and cycling magazines, the folks at BH, while taking that side of the equation very seriously, will never allow lab results to trump real-world ride testing. They boast multiple Grand Tour veterans on their staff and rely heavily on their current crop of racers to refine their product. During development, as each iteration of the Ultralight emerged from the mold with slight adjustments in layup or carbon to refine ride quality, these Spanish riders headed for France.

Crossing a pass on the Spanish-French border called the Somport, their ride testing carried them into France. From there the test route ticks off the hors catégorie Col de Marie-Blanque and the first category Col d’Aubisque before rolling back into Spain at the summit of the hors catégorie Puerto de Portalet. We hate to be the bearers of bad news, but Spain, the BH Ultralight has been cheating on you with France. If it was us, we’d want to know.

A French Affair
So what did the thousands of meters of French climbing teach these Spanish bicycle manufacturers? As one would expect with a French affair, there were fireworks. The BH Ultralight is a revelation and far and away the best bike BH has ever made. If you ride a G5 you know this is high praise. For starters a 56-cm frame, painted and ready to build, tips the scales at 750 grams. BH is so confident the advertised weight is in line with actual production weights they unabashedly claim their bike is the lightest production bike in the world. Obviously, this conflicts with some other claims in the industry. If we rode a 56 cm we would put the competing frames on the scale and tell you what we find, unfortunately we ride bikes in the 60-62 cm range and no one makes weight claims based on those monsters. It was for this reason that our test bike impressed us so much on the scale. Our complete XL bike, with SRAM Red, Reynolds 32 Carbon clinchers, and FSA K-Force Cockpit was gloriously UCI illegal at 14.25 pounds. That weight includes Xpedo Thrust 8 pedals and two water bottle cages. No crazy light tubulars, no one-off carbon components, just a ready-to-ride, every day build. Who has the lightest production frame? Who cares? This bike, in this size, with this build, is so light as to make a few grams here or there meaningless.

Achieving this weight went hand in hand with achieving the exact ride quality BH was chasing. Light for light’s sake, or stiff for stiff’s sake, was not part of the design brief. To deliver on a light, stiff frame with all-day ride quality they didn’t go looking for a magic bullet. Instead, they paid obsessive attention to layup and carbon variety. In place of big sheets of high-mod carbon stacked on top of each other at 45-degree angles, each and every tube along its entire length was painstakingly examined. The shape, size and orientation of each and every ply was refined, refined, refined and then refined again to deliver the exact characteristics BH desired.

The heavy lifting is done during a process called “kitting.” Every part of the carbon frame has a specific “kit,” with all the pieces and varieties of carbon needed, in the exact shapes prescribed with detailed layup instructions for that part of the mold. Those “kits” are weighed every step of the way to make sure no extraneous layers or irregular shapes get in the mold. “Kitting” is not unique to BH, but the obsessive attention they pay to the process may be. BH likens it to building a high-end fork. Since the fork is under such demanding loads and any failure would be catastrophic, the resulting “kits” are incredibly detailed. Most frames, especially the monocoque variety, typically have much simpler “kits.” BH took fork level precision and applied it to every part of the Ultralight monocoque.

Once in the mold the tired and true plastic bladder couldn’t create the high, even pressure needed due to the limited material and detailed layup. Even the next level latex technology wasn’t going to achieve the results they wanted. BH developed another process, and like some other brands, it’s a process they claim is unique to them. That’s as much as they are prepared to tell us, but then every affair has its secrets.

Getting down to 750 grams meant banishing metal of any kind. The dropouts are carbon, the press fit BB has no alloy sleeves and even the fork crown does without an alloy race for the headset. Internal cable routing was forsaken as BH could route externally with less weight. Of course, they use molded carbon brackets, no riveted alloy here. A nice touch is the cable guide under the BB. It allows you to cross the derailleur cables for a more direct route from the bars to the head tube if you desire.

But, as BH themselves claim, numbers can only get you so far. They relied on road testing to verify the light weight, which didn’t come at the expense of ride quality. To help deliver stiffness BH worked with FSA and Wilier to create the BB386EVO standard. Debuting on the Ultralight, the new standard has less to do with stiff cranks than stiff frames. The 86-mm bottom bracket shell the standard requires gave BH a huge amount of real estate upon which to mold the other tubes. The result is and incredibly robust bottom half. From the tapered steer tube to the rear drop out, the power center of the bike is enormous. The chain stays specifically are extremely tall and very wideset. Which creates not only stiffness but a perfect platform for today’s wide body rims.

Of course the dark side of power transfer is an unforgiving ride, and as you can imagine that was something BH wanted to avoid during their 200 km jaunts in the Pyrenees. They looked to the tried-and-true method of investing a stiff platform with compliance, allowing the seat cluster to flex. This is one of the main reasons the integrated seat mast is a dinosaur; a carbon 27.2 seat post, such as the Ultralight uses, simply and effectively invests the bike with some compliance. BH also molds arrow-shaft-thin seat stays, to leave the seat post free to do its job.

In frame design, the adage is usually form follows function, but at some distance. This does not appear to be the case with the Ultralight. Each and every tube is a simple affair, no kinks, or curves, no strange bows or ridges. Interestingly, the bike seems to echo the squoval shapes and thin seat stays of Cervelo, a brand renowned for bikes based on engineering not aesthetics, bikes which are all the more beautiful because of it.

To ride the Ultralight is to experience power transfer matched by fewer bikes than we can count on one hand. But thanks to the incredible low weight, that power transfer is felt not just at big efforts but from the first pedal stroke. It is lively and crisp the moment you turn from your driveway or clip-in from a stop sign. Under big power it is just as scintillating. Jump away from the group and you will create a bigger gap in fewer pedal strokes than almost any other bike in the peloton. Take that power transfer climbing, throw in the light weight, and you will get an inkling of how the climbing specialists of the world do what they do. The Ultralight changes tempo in a heartbeat. For the non-climbing specialists, the feeling will be startling. You will be able to make the kinds of accelerations that shred the group, then settle into a tempo a gear higher than you normally ride. On a long climb this will translate into shaving minutes off your PR.

One of the biggest benefits of the extremely light platform BH provides is the ability to reach its low weight targets without relying on super light tubulars. Wheels in the 1,000-gram range accelerate like crazy and look great on the scale, but they invest the bike with a twitchiness we find hard to forgive when descending. The 1,320-gram Reynolds 32s have plenty to offer while climbing, yet don’t hamper your stability while descending.

BH, with their long road race pedigree, knows a thing or two about geometry and the Ultralight, like the G5 before it, benefits from this. Their recipe is a steep head tube, with a slightly more relaxed seat tube. This gives the Ultralight rider the ability carve tight, nimble lines and slash through tiny gaps in a mad dash for the line by simply sliding forward on the seat. Slide back and the relaxed seat tube creates a neutral position, banishing any twitchy feeling in favor of an intuitive ride and confident feel. While climbing in the saddle, the seat angle combines with 405-mm chain stays to tuck the rear wheel right under your power center. This combination also helps the full gas, explosive out-of-the-saddle jumps feel composed, planted and exceptionally fast.

The Ultralight’s triple focus on weight, stiffness and ride quality is incredibly successful, but that ride quality is race-focused. The compliance is not designed to be comfortable, it is designed to get you to the end of a long day ready to sprint. The bike is stiff, especially through the front end. The one and one-half-inch lower bearing takes big impacts right up the steer tube and into your arms. The rear is better at managing rough road, especially if you run quite a bit of seat post, but don’t expect a magic carpet ride.

The Rider
You like the idea of having the lightest bike money can buy, without relying on gimmicky carbon. You understand that, while the price is steep, riding a bike as lively and confident as the Ultralight is simply more fun.

The Bottom Line
Price: $8,900
Size tested: XL
Weight: 14.25 lbs (with pedals and bottle cages)
Detasails: SRAM RED, FSA K-Force cockpit, Reynolds 32 carbon clinchers, San Marco ASP Lite saddle

From issue 13. Buy it here.