This story originally appeared on WIRED UK.Design innovation and material science in bike design is on a par with sports such as F1, and Grand Tour bikes are built with pure performance in mind. But a bike that excels at "climbing" on steep mountain stages will lose valuable time in a time-trial where aerodynamics are everything and even bike handling is compromised for pure speed. Take that same time-trial bike on a mountain or a flat stage with a big group of riders jostling for position and its twitchy handling would make it at best unwieldy, and at worst dangerous.Of course, riders could ride one "do-it-all" bike, the "Aero" and "Climbing" bikes are versatile rides available to and ridden by cycling enthusiasts the world over. However, time-trial bikes are specialist beasts, the right tool for the job in heads-down timed efforts only.Here’s our guide to the three main types of bikes raced by the pro peloton in this year’s Tour de France.
The Aero Bike
Early aero bike development (in the mid 1980s) was born out of experiments in changing the profile of a bike’s frame tubing for aerodynamic benefit—just like racing cars. The better the bike slips through the air, the more significant the savings in energy used to propel it (and time saved in a race).By the time Greg Lemond won the 1989 Tour de France by just 58 seconds, in a now legendary final stage solo time-trial (wearing an aero helmet and with aerodynamic—or tri—bars), riders could see the immediate advantage. "Aero" as a design objective was here to stay.
Thirty years later and aero is still the buzzword in bike design. Whether you’re a pro-tour rider or weekend warrior, the last five years have seen an acceleration in both the technological development and the sheer variety of aero bikes now available to the public.
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Modern aero bikes still feature those tell-tale "sculpted in a wind tunnel " carbon-fiber profiles, adding tighter tolerances between frames and wheels and often sport one-piece handlebar and stem combinations (where a clean front-end of the bike cuts through the air more efficiently).They also integrate cable routing hidden inside the frame for gears and brakes (more clean lines and less drag) or have done away with cabled gearing completely, switching to systems such as Shimano’s Di2 electronic shifting (featuring a thin wire sending signals from the shifter to the rear mech) or SRAM’s eTap wireless shifting (via their proprietary wireless protocol Airea).
These rides may also "drop" the front end of the bike slightly to put a rider in a more aerodynamic position (bearing in mind the rider will cause "drag" as well and the bike). There’s been a dramatic rise in the popularity of skin-tight aero clothing, too.
Aero bikes often feature a "deep section" wheelset where the rim can run between 40–90 mm in depth—the larger, smoother profile aiding smooth air travel over its surface.
The tradeoff for this "aero" build? Aero bikes often weigh more than their featherweight climbing equivalents—and are often less comfortable than regular/all-day/endurance road bikes, as the frames are designed with profile and stiffness for power transfer as a priority.Pro riders will use the aero bike in races such as the Tour de France for longer, flatter stages as results show that an aero bike can be up to four minutes faster over a flat 40-km course (if riding conditions are favorable) as well as in sprint stages where the aerodynamic shape and uncompromising stiffness is an asset in getting you over the line in first place.
The Climbing BikeWhat do pro riders want when they’re climbing impossibly steep mountains, often for hours at a time? Something light. Easy. Well, it's almost that easy. Grand Tour Climbing bikes are light, but they must be no lighter than the UCI’s (cycling’s governing body) 6.8-kg minimum weight rule, and they have to handle well—riding in and out of the saddle.
The tube profiles on a climbing bike frame won’t typically be as extreme as aero bikes—adding the extra carbon fibre for those oversized deep-profile tubes takes extra material and adds weight. The wheels won’t be as deep section as an aero bike or time-trial bike, either, the minimal weight disadvantage isn’t worth it. In a world where gramme-shaving could be the difference of first and second place on a mountain stage, riders will nine times out of 10 pick the lightest bike possible (bear in mind it’s also a psychological advantage).When does a rider chose a climbing bike over an aero bike, though? This is one of the hottest topics in competitive riding right now—both in the pro tour and at the café-stop-on-a-weekend club run. Yes, there is advantage to a more aerodynamic bike, but only typically on grades of up to six per cent. On grades over six per cent – the iconic Tour de France climb of Alpe d’Huez averages eight to 11 percent and Mont Ventoux also averages 8 percent—a climbing bike is still the weapon of choice. The weight always beats aerodynamic advantage at those speeds and gradients.
The Time-Trial Bike
In a time-trial race, a rider (or team of riders) are pitted against the clock to be the fastest around a set course. It’s one of the purest kinds of racing, and one where the strongest rider, in the most aerodynamic position, should win the day.
Yes, there’s a certain amount of expert bike handling involved (and at speed), but the discipline is very different from jostling for position in a busy peloton on a flat or sprint stage, or the cat-and-mouse competition of a long climbing stage.
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The holy grail of pro-tour design is obviously to engineer a bike as light, stiff, aerodynamic and as comfortable as possible. Unfortunately, some of these objectives end up competing with each other: aero bike design adds weight, Climbing bikes compromise on aerodynamics. What about time-trial (TT) bikes? They are light, stiff and aero, but comfort (and maneuverability) take a hit.
TT bikes are a specialist aerodynamic tool, and for good reason. As soon as a rider breaks 15 kph the biggest force to contend with is drag, and the faster you go, the greater the drag (not ideal if you’re a pro rider traveling at 60 kph). These bikes are designed for predominantly flat racing where the difference between the top ten places could be just seconds.Looking at TT bikes, the most distinctive element is the stretched out position they put the rider in: low, aerodynamic and aggressive—perfect for flat-out racing. The bike achieves this with a more extreme geometry, (the frame angles which dictate rider position and riding characteristics), most notably the steep angle of the seat-tube, pushing the rider forward and on to aero-bars (made popular again by Lemond’s famous ‘Tour win) protruding from the front.The body is also moved from the traditional position, with the rider sitting on the saddle just behind the bottom bracket (where the front chainrings are mounted) to over or in front of the bottom bracket, thus engaging different muscle groups for an increased power output. Look out for TT bikes on stages two (on Sunday, July 7) and 13 (on Friday, July 19) of the 2019 Tour de France.
This story originally appeared on WIRED UK.
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