By Tom Demerly for TriSports.com
Spain’s BH Bicycles joins the lead pack in the race to the bottom of the scale with the BH Ultralight, a lightweight carbon fiber frameset built with stiffness enhancing features such as a proprietary bottom bracket and special carbon lay-up. Claimed weight: 1.65 pounds for the frame. We decided to put a 254 pound rider on it for two months to see what would happen.
Consumers love “golden BB” metrics, the single number they can compare to measure “best-ness”. Some consider bike weight that metric, others argue wind tunnel results. Internet forums are built around building lighter bikes. Set against that background the BH Ultralight is a contender.
How light is the BH Ultralight? BH Bicycles claims “Less than 750 grams in a 56 cm frame size”, or 1.65 pounds. Impressive. But is it functional in the real world? We decided to find out by putting a 254 pound rider on a 1.65 pound frame. To frame this, our test rider weighs 156.3 times more than the bike frame he is on. While our test rider weighs over a tenth of a ton, his bike frame weighed about the same as a dense loaf of bread. BH Bicycles also covers the bike with a Limited Warranty: “BH frames sold in the USA and Canada are covered against defects in workmanship and materials for as long as the frame is owned by the original owner.” Although the warranty does not cover normal wear and tear according to BH Bicycles, that is an impressive endrosement.
Mike Gibbs of TriSports.com built up a size Extra Large (56cm seat tube measured center to top, the same as a Cervelo R3 in 61cm size name) BH Ultralight using SRAM Red components, Mavic Ksyrium clincher wheels, a Selle Italia Flite saddle and PRO Stealth Evo cockpit with two X-Lab Gorilla carbon cages and a Garmin Edge GPS unit. Total weight: 15.3 pounds measured. This isn’t a lightweight build, and a lightweight enthusiast could shave pounds off this. It is a “real world” build that is intended to be ridden every day on all roads by a heavy rider.
There are two features that contribute to the BH Ultralight’s weight and ride quality. The first is the BB386EVO bottom bracket. This new bottom bracket configuration was designed largely by component manufacturer Full Speed Ahead (FSA). The system is based on the common BB30 configuration but beefed up substantially for greater stiffness in the bottom bracket and the frame/bottom bracket interface. BB386EVO also allows larger chainstays and influences crank design. In many ways, the light weight and frame feel of the BH Ultralight emanates from the BB386EVO design. If resistance to lateral deflection under pedal load and lighter weight is the high bar for a bottom bracket BB386EVO appears to clear it.
I spoke with Tim Jackson, Marketing Manager for BH Bicycles in the U.S. about BB386EVO compatibility with other cranks such as SRAM and Shimano. “The only limitation is BB30” said Jackson, “BB30 bottom brackets won’t work”. He mentioned a press fit bearing adapter developed by BH specifically for the BB386EVO configuration. This adapter enables the use of “…any standard 24 mm bottom bracket compatible crank” according to Jackson. There are limitations on crank-based power measurement though, with current SRM and Quark units not fitting. Additionally, FSA will introduce a BB386EVO specific version of the popular FSA SLK crank later this year. That brings direct compatibility with BB386EVO up to two cranks and adapter-served compatibility for many others currently available. I’ll suggest this degree of flexibility effectively takes compatibility concerns off the table.
Are the benefits of BB386EVO worth using an adapter on some cranks or limiting your crank selection to those directly compatible? I’ll say “yes”. Changing a crank or adding a power meter can only exert so much change on the performance of a bike. BB386EVO likely provides a per-pedal-stroke greater benefit than switching cranks or adding crank-based power measurement. Additionally, pedal and wheel based power meters still work fine, and the FSA BB386EVO crank is a beautifully finished well made crank that is compatible with SRAM, Shimano and Campagnolo 10 speed drivetrains. The idea of more closely integrating crank, bottom bracket and frame to reduce weight and improve performance isn’t a new one, and it is a proven one. Cannondale did it along with a handful of other builders. The concept is proven. The execution on the BH Ultralight is very good.
The other weight saving, stiffness enhancing feature on the BH Ultralight is the carbon fiber lay-up. Consumers have a tough time visualizing the effect of different carbon fiber lay-ups on performance until they ride, or pay for, a bike. Different carbon lay-ups account for much of the difference between a $1500 complete carbon fiber bike and a $15,000 carbon fiber bike. They also account for a massive range of qualities that manifest themselves in everything from crash survivability to road feel and weight. The lay-up on the BH Ultralight, in concert with BB386EVO, does produce a ride tangibly unlike any bike I’ve ridden. It isn’t subtle. Test rider Mike Gibbs said, “I can’t explain the physics” he was so baffled by the incongruent relationship between weight, stiffness and even ride comfort. Perhaps more so than the weight of the bike, the attention-getting stiffness of the bottom bracket sets this frame apart from others.
Starting at the front of the bike BH Bicycles uses an all carbon fiber headtube without any metal headset races. Everything is carbon fiber on the head tube and fork, including the surfaces the bearings rest on. The fork is a proprietary BH Bicycles design with a massive crown and 1.5″ diameter bottom race that aids response and lateral stiffness. While the straight blades suggest a jackhammer ride, the result (even on a smaller frame in my size) was utterly civilized. On out of the saddle efforts it only got better.
The use of the large 1.5″ diameter bottom headset race enables the down tube to be larger also, increasing frame stiffness and shock absorption since there is more surface area for vibration to be disbursed over. The transition from one frame section to another within the molded frame is clean with no seam lines. At the seattube a skeletonized alloy clamp fixes the seatpost with a single bolt. The seatpost clamp is modular and replaceable.
The seatpost is made for BH Bicycles by FSA and uses two adjustment bolts for saddle angle . It has 2 cm of setback from the center of the post. Both bolts are accessible from the bottom for ease of angular saddle adjustment, a thoughtful feature. The bolts are long enough to accommodate most carbon rail saddles, good thinking for BH since many Orbea models require additional, longer seat clamp hardware for taller carbon fiber rail saddles. The entire design is sturdy and simple. Well done.
The frame uses molded-on cable stops with slots for easy cable replacement. BH was thoughtful enough to ship the bike with two polymer anti-scuff decals at the head tube so your drivetrain cable housings don’t abrade the head tube of the frame. The drivetrain cables route under the square-ish down tube. BH put the cable guides in the right place since shifting and braking are crisp. The cable stops seem bomber since they are part of the frame, another boon to shift performance.
The rear end of the BH Ultralight borrows a number of proven themes originally developed on the Cervelo R3 including a tapered seat tube and gossamer seat stays. BH does take full advantage of the BB386EVO bottom bracket by mounting a pair of massive chain stays with a Serotta-esque “S” curve to them. This combination of vertically thick chainstay and adding curvature to improve ride quality is a unique morphing of design themes that accounts for a lot of the uncommon ride quality.
Our Clydesdale test rider, Mike Gibbs of TriSports.com, finished his bike off with a PRO Stealth integrated cockpit that uses a one piece molded carbon fiber stem and drop handlebar. Other trim items on the bike were the proven X-Lab Gorilla bottle cages. Mike kept the integrity of the component kit by using the excellent SRAM Red brake calipers for this build. The end result is his dependable, stiff 15.3 pound complete bike including his Garmin GPS.
Mike spent two months and about 500 miles on the bike. Zero problems. This includes long rides on rough roads. Mike also pointed out that, while the stiffness of the bottom bracket exceeded anything he’s ridden, the ride quality was better than many stiffness-oriented carbon fiber frames such as the Scott Addict R1.
Having a 250-pound plus rider on a 15- pound bike is about the same passenger to vehicle weight ratio as having three full grown African bull elephants ride in a Ford Mustang. That makes the engineering of a 15-pound vehicle supporting a 250-pound rider all the more impressive. In addition the the vehicle to load ratio, the ride quality and component performance on the BH Ultralight is well above some other high road frames and a contender for industry best along with other well made, high end carbon fiber road frames.
The BH Ultralight frameset is $4299 and is sold in five sizes with T-Shirt size names; XS,S,M,L and Mike’s XL. Mike’s Size XL runs similar in geometry to Cervelo’s 61cm R3. Both the 61cm Cervelo R3 and the Size XL BH Ultralight have a 57cm seat tube measured from center to top. It’s easy to build a sub-$10,000 ultra-light super bike using this frame. Considering the great ride quality and the strength of the frame based on our tests with Mike the BH Ultralight may be easy on the scales but it’s a heavy hitter for the light weight frame shopper.