TOUR’s tests utilize assessments and grades that are based on standardized and reproducible test methods developed in collaboration with external experts. For more than twenty years, we’ve consistently sought to improve our methodology. Today, the method we employ sets the standard; there’s no better way to objectively benchmark framesets and road bikes components. The following is an overview of our methods and test systems. The grade system is: 1 = Very Good, 2 = Good, 3 = Satisfactory, 4 = Sufficient, 5 = Failing.
Determining frame geometry
TOUR’s geometry test rig determines all relevant frame dimensions according to a uniform method of measurement. It is independent of any data supplied by the manufacturer. Different frames and geometries can thus be compared on a standardized basis. In order to do this, the frameset is mounted to a jig. Then a laser pointer is directed at a predefined series of measurement points on the frame and the fork. TOUR uses the the resulting horizontal and vertical coordinates to calculate all dimensions and angles necessary for geometry representation. This forms the basis for calculating stack to reach (STR) and is used to compute corrected weights.
The consensus among racing cyclists is that the bike should be light. But since there isn’t any agreed upon, uniform sizing system for road bike frames, a direct weight comparison between two frames is difficult. Therefore, TOUR works with weight-adjusted data to allow for the exact comparison of different frames and forks, regardless of their size. To do this, all test bikes are completely disassembled. The individual weights of the frames, forks and headsets are recorded. Each frame is weighed with the front derailleur socket, the seatpost clamp and the cable guide under the bottom bracket. If no front front derailleur socket is riveted or welded to the frame, a front derailleur clamp is included instead and added to the weight total. Frames that either deviate from the standard test size of 57 cm (22.4″) or from the classic diamond shape then have their weight computationally adjusted to fit the standard. For example, the theoretically lower frame weight of a sloping frame is offset by adding the weight difference a longer seatpost entails. Forks are weighed together with the headset cones, the stem cap and cap screw and are then mathematically corrected to a standard shaft length of 225 mm (8.86″). Frameset weight is thus composed of the adjusted weights for the frame in size 57 and the fork with a 225 millimeter shaft including the headset. Frameset weight makes up 25 percent of the final grade.
As a rule, modern road frame have a very stable ride. Twenty years ago, however, when TOUR first started such tests, we had to deal with the fact that road bike frames could suddenly develop judder (vibrations) at medium to high speeds that was difficult or impossible for the rider to subdue. Sometimes either a gust of wind or a slight imbalance in one of the the wheels was enough to cause the bike to vibrate. The best remedy was (and is) a frame with a high amount of rigidity at the steering column. The stiffer it is, the better ride stability and steering precision becomes. In order to determine the exact amount of steering column stiffness, the frame is rotated by 90 degrees and clamped into a test rig on its side. Clamping is done in a manner to realistically simulate normal riding stresses. Instead of the fork, a fork dummy is installed. A defined amount of torsional force is applied, with a dial gauge indicating deflection. TOUR then takes initiated force and torsional deflection to calculate steering column rigidity in newton meters per degree (Nm/degree). Ride stability makes up 15 percent of the final grade.
Lateral stiffness and comfort of the fork
Riding safety, steering precision and the road bike’s comfort depend not only on the frame, but are also largely influenced by the fork’s characteristics. The less the fork is deformed by lateral forces, the easier it is to steer the bike through corners. The more the fork absorbs road buzz in the direction of travel, the less the hands are strained. The fork testing rig allows us to measure the fork’s deflection in two load directions. The fork is clamped into the test rig as it would be mounted on a frame. We initially measure flex in the riding direction (comfort), then the fork’s lateral stiffness. The quotient of test load and deflection results in fork rigidity measured in newtons per millimeter (N/mm). The lateral stiffness, which is safety relevant, makes up 15 percent of the final grade. Springiness and the fork’s flex (i.e. its comfort) make up 10 percent of the final grade.
Nothing bothers racing cyclists more than if some of their pedaling power ends up deforming the frame rather than speeding them along. Therefore, a very high level of bottom bracket stiffness is the optimum. A test system was developed that simulates a rider sprinting and really putting power into the cranks. The frameset is fixed onto the jig with the quick releases in a realistic manner and then equipped with a crank dummy. Thanks to a realistic rear wheel contact point equipped with a typical degree of free movement, frame load and deflection movement during the test are approximately equal to those on the street. The rear wheel can rotate out of the track under the chain’s pull, and the frame’s vertical inclination (caused by sprinting) imposes large amounts of lateral force on the frame. Under this test load, we measure how far a pedal is diverted perpendicularly and transversely to the riding direction. The test load and the deflection it results in are used to calculate bottom bracket stiffness in Newtons per millimeter (N/mm). Stiffness makes up 10 percent of the final grade.
At first glance, one wonders how exactly a diamond frame is supposed to have a lot of movement in a vertical direction. But, thanks to design concepts such as sloping frames with long seatpost, modern materials like carbon fiber, and new seatposts designed as suspension springs, there are now significant differences in comfort between various bicycle frames. The comfort test can measure frame comfort and grade it. The frameset is clamped in an upright manner at the dropouts . Frame and fork can perform realistic deflections and flexing movements. Suspension travel is measured with the manufacturer-supplied seatpost or, if none was supplied, with a standard Ritchey WCS aluminum seatpost. The seatpost is set to the standard height of 750 mm on a standard frame height of 57 cm (22.4″) between the bottom bracket and center of the saddles rails. Behind the intersection of the seat tube and frame, a test load at the seatpost hangs down and results in a certain amount of deflection, illustrating the frame’s elasticity. Dividing the test load through the resultant amount of travel gives the spring stiffness of the frame. This makes up 10 percent of the final grade.
What good is the best paint job if it isn’t durable? The TOUR paint test simulates chipping through rocks and provides an indication of the durability of the protective overcoat. The paint’s mechanical resistance is tested at several different areas. This takes into account that various parts of the frame can be painted differently and that several different materials can be used in one frame. The paint test utilizes a chisel to simulates rock chipping or the chain hitting the stays. Starting at a height of 10 cm (3.9″), height is increased by ten centimeters until the the paint yields or the maximum height of 50 cm (19.7″) is reached. The paint test makes up 5 percent of the final grade.
To grade a bike’s finish, we assess the qualitative appearance of its surfaces, build quality of the frame, whether small details were solved in a competent manner and how components were matched to each other optically. Finish makes up 5 percent of the final grade.
By law, an instruction manual (IM) must be included for the bicycle to constitute a complete product. IMs with racing bike specific details, illustrations and safety instructions are graded as very good = 1.0. A generic IM gets a grade of 3.0, whereas a missing IM is graded as failing = 5.0. The grade for the instruction manual makes up 2.5 percent of the final grade.
Garantee and crash replacement
Besides the pure quality of the product, the manufacturer’s guarantee and crash replacement plan are important items that add value to the product . A guarantee is voluntarily provided by the manufacturer and is usually only valid for the frame. The statutory liability for defects, formerly called the warranty, is valid for a period of two years after the purchase. During that time period, the retailer is liable, i.e. responsible for the whole product being free of defects at the time of delivery to the customer. As a crash replacement plan, some manufacturers offer to replace purchased framesets that are damaged within a certain period of time due to an accident for a special price. Therefore, only guarantees that run longer than two years improve this grade. A frame and fork guarantee of more than five years merits a good = 2.0. A three to five year guarantee = 3.0, less than three years is a 4.0. If the guarantee excludes the fork or racing use, the grade drops by one level. If the guarantee offers a crash replacement, the grade improves by one level. The garantee makes up 2.5 percent of the frameset’s final grade.
To measure the stiffness of a wheel, it’s firmly clamped at the hub and lateral pressure is applied at the rim. The rim’s deflection is measured exactly. High lateral stiffness makes the wheel stable, allows for precise steering and puts less stress on the spokes. Overloading the wheel with high amounts of force shows how the wheel behaves and whether spokes or nipples then can still set. After overloading, the wheel’s trueness is measured. Wheels which weren’t initially stress-relieved now show larger tolerances and are less true.
NEW: Stiffness test system for complete bikes
Time trial bikes are at the forefront of road racing development. Compared to a classic road bike, radical seat positioning and integrated handlebar, stem, and fork systems change virtually everything. To meet the special requirements of this breed of bicycle, the new pneumatic testing system can measure stiffness of the system consisting of frame and fork. To do so, it’s only necessary to replace the wheels with realistic wheel axle dummies which are connected to the pneumatic test system. The bicycle is then mounted in a normal, vertical manner and defined forces are applied to the bottom bracket area. This test system, completely newly developed, uses the measured amount of lateral deflection and frameset stiffness to calculate ride stability.
Planning and execution of test rigs and laboratory equipment has been done almost exclusively in close cooperation with the Zedler Institute for Bicycle Technology and Security GmbH. CEO Dirk Zedler is a graduate engineer of vehicle engineering and publicly appointed and sworn expert for bicycles. The active road cyclist and five time Transalp finisher started working for TOUR at the beginning of 1994. Besides the “Workshop” section of TOUR, he has authored many important articles about road bike technology and safety. More info can be found at www.zedler.de
In the last twenty years, TOUR’s modern bicycle testing has been recognized for setting new standards and changing road bikes in a positive manner. Through TOUR’s efforts, concepts such as the stiffness to weight factor, STW for short, have become a common language throughout the bicycle industry. Manufacturers who want to optimize their frames and components before launching them can have them tested in the Zedler Institute’s laboratory. If a larger volume of testing is called for, testing equipment can also be purchased and utilized in the company’s own lab.
Text by the editorial staff of TOUR, translated by Kai Hilbertz