Remember that wild Hope HBT track bike British Cycling used at the Tokyo Olympics? Well Hope, Lotus, and British Cycling have updated that bike ahead of the Paris Olympics and are seemingly once again out to break the internet. The HBT famously featured wide and wild fork legs and seat stays. The new bike retains those wide features and now adds a Formula 1 rollover bar airbox-esque split seat post.
The new Hope HBT Paris is an evolution of the Toyko bike and the result of the continued collaboration between British Cycling, Lotus Engineering, Renishaw, and Hope Technology. Lotus are responsible for the forks and handlebars, Hope produce the frame, while additive manufacturing experts Renishaw assist in the production of “crucial components,” wind tunnel models, and additional design support, according to a British Cycling press release.
While British Cycling has announced the new bike today and provided these pictures, it has also remained intentionally tight-lipped on any actual performance details around the new bike. There are no drag reduction numbers, or watts-saved comparisons, and there are certainly no explanations into the new seat post design.
That said, with most of the new bike a carry-over from the existing HBT frame and fork used in Tokyo, we already know a lot about its design aspects. Hope, for example, already explained ahead of the previous Games that while the wider fork stance does help with airflow between the wheel and fork, the main benefit is in directing airflow around the rider’s legs, a little like an upstream fairing or splitter reducing drag. Hope designed the seat stays, sitting behind the rider’s legs as they do, to perform in a similar fashion downstream and help smooth out the airflow coming off the legs and thus reduce drag.
Manufacturers could easily design seat stay-less bikes, but UCI regulations mandate their inclusion. As such, many brands make the stays as small, thin, and low as possible on aero bikes. Hope effectively did the opposite in making the stays as tall, thin, and high as possible, again to act as a aerodynamic splitter behind the rider. Both design philosophies rely on huge chain stays (as evident on the Hope HBT and HBT Paris) and bottom bracket areas to retain that all-important frame stiffness on the track.
So that’s what we know. What about the updates Hope and BC won’t tell us about? Well, let’s start with that seat post. It looks a lot like the air intake above the driver’s head on an F1 car, and a bit like someone fell asleep face-down on the “enlarge” function on the design files for the new Trek Madone. That Isoflow hole on the Trek Madone seat tube is intended to accelerate airflow through the hole into the low-pressure zone behind the rider. In other words, Trek claims the magic happens inside and through the hole. With the deep, rearward-swooping walls on the Hope seat post, it could be the gains could come from these walls controlling the flow off the rider’s legs. In other words, it’s the outside surfaces at work here.
There is also a major update on the rear-facing side of the forks. The forks feature a serrated or sawtooth pattern that is new to the Hope HBT-Paris. Again, neither BC nor Lotus has provided any details on the reason or theory behind the serrated edge in the press release, but we can speculate to our heart’s content. Sawtooth trailing-edge serrations, also known as trailing-edge notches, are commonly used on aircraft wings, propellor blades, jet engine covers, and wind turbine blades. The sawtooth profile is located on the trailing edge of the object and helps improve airflow, reducing turbulence and drag. The design is used in these fields partly to reduce audible aerodynamic noise.
The sawtooth serrations work by reducing the vortices generated as a result of the pressure difference between the upper and lower surfaces of the wing. The sawtooth serrations break up the vortices into smaller eddies, a technique known as “vortex shedding control.” This vortex shedding control from the serrations can have secondary effects in reducing aerodynamic drag. Even at sprint speeds, noise control is unlikely top of British Cycling’s objectives for a track bike, but if Lotus have found a way to harness the drag-reducing properties of the sawtooth serrations on a bicycle fork … expect to see it on a road bike near you in the future.
All bikes, equipment, and clothing that nations wish to use at next year’s Olympic Games in Paris must be used in competition this year as part of the UCI’s new Track Equipment Registration Process. With the Glasgow World Championships the final opportunity to homologate new equipment, national governing bodies and manufacturers alike have been scrambling to get all their new developments completed, registered, and finally used in competition. While we can expect to see the new HBT Paris in Glasgow (that’s not confusing) next week, don’t expect every British rider to race the new frame in every race. Chances are many nations and manufacturers will be on a “used in competition” box-ticking exercise, with most new equipment intended for the Olympics given just a few laps of racing action before getting whisked away from the competition’s pesky eyes.
The new Hope HBT-Paris is now the first of that equipment we have seen images of. As we reported yesterday, there are close to 400 other new items on the way to Glasgow for the final step in their UCI/Olympic homologation process. We will bring you news and images of more of these as we get them.
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