The diamond form of a bicycle body hasn’t modified a lot because it was first invented. Triangles are an enormously sturdy form and will also be simply modified to accommodate riders of various statures. Every rider’s wants could differ, however the essence of the design needn’t change drastically.
A well-built bicycle transfers energy effectively by means of the drivetrain, steers predictably and is snug to experience for lengthy intervals of time. Overemphasizing stiffness creates a motorbike that turns each variation within the street floor into numbing vibrations whereas focusing an excessive amount of on compliance makes a motorbike that handles unpredictably and loses power by means of undue body flex. It’s within the harmonious center floor between these two extremes that good bicycles exist.
Experience high quality as an idea is extremely subjective. Moreover, the sensations you are feeling whereas using a motorbike can’t be simply attributed to anybody part or half. In sum, one would possibly really feel some mixture of the next whereas using: tyre casing, air stress, spoke and rim interaction, body design, seatpost flex, saddle padding and situation of chamois (or lack thereof). And that’s simply the rear half of the bike.
There’s a purpose why many bike opinions give attention to goal traits, like weight, geometry and aerodynamic efficiency. Attempting to isolate the efficiency of the body from the whole system is considerably akin to attempting to discern a person thread in a sock with the underside of your foot. Nonetheless, we strive our greatest.
Some ideas on flex
Stress testing being accomplished on a body as Argonaut Cycles in Bend, Oregon.
(Picture credit score: Argonaut Cycles)
We spoke with body builder Corey Lowe of Eyewater Bicycles to study extra about body composition. Lowe began within the bike business with Parlee Cycles as an engineer and body builder, then moved to Cannondale and Specialised as a design engineer with the high-performance street workforce. He has additionally accomplished contract engineering work for locations like Allied and Cervelo and presently builds customized carbon bicycles underneath the Eyewater identify.
Lowe emphasised that the body “should at all times [be considered] as an entire. There are occasions when isolating a part helps get a transparent understanding of its influence, however the finish results of how a body rides could be very a lot a recreation of the entire bundle.” As he says, “It’s comparatively simple so as to add stiffness whereas including weight. The trick is so as to add stiffness with out including weight. The fabric properties of carbon will be adjusted with the layup schedule with out essentially including weight.”
We additionally requested him about balancing stiffness and compliance: “Frames will be designed for each targets, enhancing one or the opposite utilizing layup modifications. I attempt to design frames to satisfy the efficiency targets set out after which work to optimize experience high quality and compliance from that time. These two parameters usually are not at all times mutually unique, particularly with working with carbon layup schedules and spherical tubing.”
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Finally, Lowe says, “match and geometry are the most important elements in rider consolation.”
Which tubes must be versatile, and which must be stiff?
(Picture credit score: Andy Jones)
Structurally, the best focus of stress on the body happens on the joints, particularly the backside bracket, with the center of the tubes in between seeing the least quantity of stress. The fabric used, its form and its thickness all decide the way it will react to pressure and stresses.
If the aim of the design is to place the correct quantity of fabric in the correct locations, then this implies utilizing much less materials within the locations the place it should expertise the least quantity of stress.
With a standard body design, the downtube considerably impacts the general really feel of the bicycle. It’s the essential structural component tying the underside bracket to the pinnacle tube, so it’s chargeable for sustaining torsional stiffness and stopping an excessive amount of lateral flex. If it’s too stiff, it received’t monitor the bottom nicely, but when it’s too versatile, it should really feel imprecise (i.e. scary) at excessive speeds or underneath heavy cornering hundreds.
The tough factor to bear in mind is that the correct stiffness for a rider relies on their measurement and weight. Chainstays must be sturdy sufficient to carry the wheel in place whereas transferring the power going by means of the drivetrain. The highest half of the bicycle, notably the highest tube and seat stays, add to the energy of the entire by finishing the triangles, however much less inflexible materials right here might help with discovering the correct steadiness of vertical flex.
The stiffness of the fork additionally considerably impacts consolation. Apparently, the seat tube does little or no to offer consolation or construction. Its main goal, outdoors of finishing the triangles, is absolutely simply to put the saddle in the correct place for the rider.
Strategies
(Picture credit score: Future)
How does one change the stiffness of a tube? There are basically three rules in play: materials form, thickness and diameter. Shaping is used each for aerodynamics and to encourage motion in particular instructions and ranging the thickness of the fabric at totally different factors in every tube is used for weight financial savings and adjusting experience high quality and rigidity. All else being equal, bigger diameter tubes are stronger than smaller ones. By utilizing thinner materials with a bigger diameter producers could make bikes which might be each mild and robust.
There are additionally a number of different design parts to think about along with experience high quality: aerodynamics, influence resistance, and weight all play an element, and relying on the appliance a designer could skew extra towards the route of a number of of those with a purpose to meet particular goals.
Conclusion
(Picture credit score: Future)
Experience high quality is an fascinating subject of debate partially as a result of it’s so subjective. What works for one rider could not work for one more. Bicycles from giant business gamers are designed for many who match inside a sure vary of constraints. Riders on both finish of the peak and/or weight bell curves would require changes to discover a bike with their desired experience high quality, and may have to hunt alternate options to mass manufacturing choices.
Finally, the most important positive factors to be made in terms of rider consolation are within the seatpost and tires. A seatpost designed to flex will take away rather more street vibration than the body, and ditto for tires: increased quantity tires at decrease pressures are key. In the case of body design, match is the primary most important component. A nicely designed-frame strikes a wholesome steadiness between stiffness and compliance with a purpose to fulfill its true goal: making cyclists completely happy.
