I was given the opportunity to ask some questions to a TT frame designer. So I put the call out for your questions and passed them on. Juergen Falke is the Director of Products at the Merida R and D centre in Germany and he graciously took time out between the Giro and Le Tour to answer our questions.
How much of the design process is driven by:
-Intellectual property challenges (ie patents owned by other bike companies)
-Marketing (adding features not because they improve quality, but because they make the bike look unique)
Intellectual property is not a big deal for road and tri-bikes frames. This is really a subject at full-suspension mountain-bike and bike components, but not that much at road frames.
Marketing like mentioned from your side is evident, because “sex sells”. And most consumers and athletes have the behaviour of believing nice sounding fairy tales – the real truth is not easy to find and sometimes not what people love to hear. Therefore visible features which can be promoted are evident for the success of a bike.
How much of a compromise is there between aero design and handling?
Not much. The compromises in between aerodynamics and other characteristics that are hard to realize side by side are:
• keeping stiffness for precise handling,
• adding some comfort while knowing aerodynamic design creates harsher frames,
• forks and seat-posts,
• and bringing weight down despite the larger cross-sections and higher section profiles at tubes, rims…
This is the advantage of the new REACTO: It feels like a well performing regular road-bike in terms of frames stiffness at the head-tube (steering control) and bottom-bracket (power-transfer),it offers fork and saddle-comfort like a regular frame with a flexible 27,2 carbon seat-post (while most competitor’s aero frames, such as Specialized Venge or Cervelo S5 are extremely harsh/rigid) and has no big weight penalty: The weight compared with the MERIDA Scultura frame-set, when all relevant parts are included is less than 200 grams.
Is there an industry standard margin of safety, especially for composites?
No, and this not needed. There are international safety standards for the different bike categories that are quite serious (EN at Europe, JIS at Japan, BS at UK) and these standards define the needed performance and fatigue strength without caring for the used material. A 750 grams carbon road-frame need to pass the same safety standard than a 1.,6 kilogram aluminium or a 2.,2kilo steel-frame.
This is the point. And this has to tested and certified, for every new product.
Besides, leading bike-magazines are doing their own lab-testing and offer a neutral database of frame performances.
A superlight carbon composite frames which offers sufficient stiffness figures and passes the legal standards is simply safe.
What FEA / CAD / CFD packages do they use?
FE analysis of a carbon frames doesn’t make sense, because composite duroplastics are not homogenous materials. Such an analysis shows stress points, but how to manage them can be just figured out by intense lab-testing and improving by experience and “trial and error”.
3D CAD: We are working with Pro-E and Auotdesk ALIAS, completely different software packages for different applications.
CFD: At the bicycle field, this is a marketing tool and nothing more. A bike including rider is 10 times more delicate than a formula 1 car.
Wheels are spinning, cranks rotating, legs moving up and down. CFD might help to compare the aerodynamic quality of different tube or rim-shapes in an isolated view, but never the whole system. You can compare different down-tube profiles isolated with CFD, or a separate handlebar – never the full package with trustable results.
But it is possible to show nice and colourful pics about air-streams with CFD, good for marketing ;-)
Real aerodynamic results can be just figured out at the wind-tunnel, and the tunnel just shows where you are, but doesn’t explain why. Good aero-performance is experience, testing, testing and some good sense (and some good luck).
Why aren't we looking at a plethora of 6.8kg bikes, when they are just about standard on a road bike? I know it's not as important, but does aerodynamics cost that much weight?
Yes aerodynamics costs weight. To arrive at 6.,8 kilograms ready to race (such as the UCI is checking pro-riders bikes at world-tour races: With 2 bottle-cages, pedals, computer-mount, bike-computer, power-measurement), a weight of 6,8kg is really hard to achieve with the use of sponsor-conform parts and aero-frame plus aero-wheels.
Even Chris Frome's special tuned, brand-new Pinarello for the TdF ends finally at 6.85kg's.
Integrated rear brakes and internal cabling are problematic for home and bike shop mechanics, are the advantages worth the problems or is it something that consumer’s demand and are bikes now taking internal cable routing less seriously with the advent of electronic shifting?
This is why we are using Shimano direct-mount brakes, being in terms of aerodynamics already far better than standard brakes and having not all the penalties in daily life of full integrated brakes. Cables and wires running through the frames are a standard today for quality road bikes (even for quality MTBs), when the specific solutions are thought out well, the additional work during assembling is reasonable.
How much faster is a TT bike really?
What makes a TT bike faster than a good aerodynamic road-bike is not that much about the bike: It is the result of a more extreme body position which a TT-bike allows his rider to use, due to a far lower front and deeper position of the aero-bar.
The line between aero road and tt bike is getting finer, and lots of people don’t fit well on dedicated TT bikes, will geometry and fit start to be accommodated in an aero road bike to make it more user friendly as a TT bike.
Correct, dedicated TT-bikes are special tools designed for pro riders and specialists at a very special discipline, a real tiny target audience. Non professional athletes, including all age-group triathletes or hobby road racers have more fun (and are faster) at a triathlon derivate of a TT-bike or an aerodynamic road-bike.
This why we offerb3 different Level of aero-frames:
- The WARP TT as dedicated TT-bike for professional use, and being the tool for our World-Tour team LAMPRE-MERIDA
- Launched 2 months from now, the new WARP TRI - a specific triathlon-bike with lots of similarities with the WARP TT, but a more relaxed aero-position featuring a longer head-tube and steeper seat-tube angle, being NON UCI legal.
- The REACTO as an aerodynamic road-bike offering superb aero performance. The Reacto was tested by German “TOUR” magazine along with 12 aero road bikes at a big test in the wind-tunnel with a dummy on board. The Reacto was a close 2nd to Cervelo S5, in front of Giant Propel, Specialized Venge, BMC Timemachine and co. It is a great bike for Olympic triathlon races, but as well with flipped seat-post and aero-bar a good and universal tri-bike.
How much restraint in design is there based on UCI regulations, and would you prefer the designs to be relaxed and if so which specific parameter is the most restrictive?
Most restrictive parameter is the requested diamond shape of the frame with a closed front and rear-triangle. Just remember the “Lotus” frame of Chris Boardman or the Softride V-frames used in the 90s, before the UCI killed such kinds of developments.
What is the next evolution of TT bikes??
At the moment and without change of the UCI regulation, I see no short term evolution at the TT-bikes.
Keeping under consideration the level of TT-bikes is extremely high – just take a look to all the machines used in the world-tour, being developed in the wind-tunnel, with integrated stems/bars, brakes…
The biggest factor to be improved is the rider and his position. This is the area to spend time.