Cycling Ergonomics
Below we get into the specifics of cycling ergonomics, but first it is important to be clear that some perspective is important. The acute injuries which can result from years of cycling on traditional diamond-frame (or DF) bicycles afflict a tiny minority of highly dedicated cyclists who have been willing to suffer through years of discomfort. The majority of people who have dealt with the same poor bicycle ergonomics have simply stopped riding because it was uncomfortable. However, the disorders associated with sedentary lifestyles pose far greater health risks than those that can be associated with cycling, even on the least ergonomic of cycles. Whatever you ride, it is better to cycle than to be sedentary. There are two main variants on the riding position of DF (diamond-frame)- the bent over position of road bikes, and the more upright position associated with mountain bikes and cruisers. To assist in navigation of our review of cycling ergonomics, the content is organized by the following menu:
Road Bike Position – leaning forward - Numbness in hands, aggravation of repetitive strain injuries such as carpal tunnel Mountain Bike/ Cruiser Position- Upright
Road Bike Position- Leaning Forward In the riding position which the traditional road bike, and most hybrid and touring bikes, place the rider, the back is flexed for prolonged periods of time, and the neck is extended to see ahead (see link). Riding in drop handlebars for long periods deepens the flexion of the back, increases the load on the arms, and forces hyperextension of the neck.
Because of the way the back is bent, it should not be surprising that so many cyclists are afflicted by back pain. Indeed, Andy Pruitt, Ed. D., director of the Boulder Center of Sports Medicine is quoted in Bicycling magazine as suggesting that the classic road bike position can help to create "a perfect storm of muscular and structural imbalances centered directly on your spine" (link). As Elliott Krakow explains in his article in the journal Dynamic Chiropractic, "The farther forward the rider leans while in the seated position, the higher the intradiscal pressure climbs in the lumbar spine" (link). Over time this pressure can contribute to herniation in the lower back.
In the road bike position the cyclist’s body weight is divided between the saddle, the pedals, and the handlebars, meaning that the arms and hands bear a great deal of the weight of the upper body. This can cause numbness in the fingers and hands, and contribute to, or aggravate, repetitive strain injuries such as carpal tunnel syndrome (see link).
Finally, the other major ergonomic issue with road bikes is their saddles. However, I will discuss bicycle saddles below, as this is a more serious issue for the more upright riding position of mountain bikes and cruisers.
Mountain Bike/ Cruiser Position- Upright
Considering the neck, back, and arm ailments that are associated with the road bike position, the more upright riding position of mountain bikes and cruisers seems like a big improvement. By being more upright the spine is not flexed as far forward, and the hands and arms do not bear weight in the same way. However, it is worth noting that this upright position can exact a toll on the lumbar discs as well, due to the fact that there is no support for the lumbar spine, and because the spine has to absorb road shocks (see link).
However, the key ergonomic problem with the upright cycling position is that, unlike the road bike position, where weight is divided between the arms, saddle, and pedals, the cyclist’s weight is moved straight back to the saddle. While the road bike position allows the rider to support more of their weight on their pedals by keeping their legs active, the more relaxed position associated with cruiser bikes in particular means this is not possible.
The bicycle saddles of diamond frame bicycles concentrate the cyclist’s weight on the delicate perineal region, causing all sorts of problems, including decreased genital blood supply, discomfort, pain, numbness, a tingling sensation, decreased sensitivity, erectile dysfunction and infertility in men, and bladder infections in women (see for example link, link, link, link, link). Saddle designs exist to deal with these problems, and there is data that suggests that some of these designs have had modest success.
However, these designs work by taking away some of the seat, such as noseless seats, and seats with cut-out sections in the middle, designed to avoid placing pressure on the perenium. From our point of view, re-designers of bicycle saddles are left trying to square a circle— the saddle needs to be small enough to get out of the way of the legs’ cycling movement, but big enough to offer an adequate resting surface. Particularly for rides of any significant duration, if a substantial portion of the body’s weight is concentrated on a small area, discomfort will result.
At Ergo Cycle our goal is to get people cycling, the more the better, so we want a cycle to be a place where people can spend a lot of time and be comfortable. With recumbent cycles one does not sit on a saddle, but rather on a seat, which distributes one’s weight not just across part of one’s bottom, but rather across the buttocks, back, and shoulders, much like a reclining chair, so that no single area of the body has to support the pressure of the body’s weight.
Imagine if you were to set up an an office or a living room that you were going to spend a lot of time in. What kind of chair would you want? A chair with back support that you could lean back on, or 1/4 to 3/4 of a barstool to perch on top of?
In the event of a rapid deceleration (i.e. a crash), cyclists on traditional DF bikes rapidly find out how vulnerable a riding position it can be. In all configurations of DF bikes, the cyclist’s center of gravity is extremely high, and it takes very little for a rider to flip headfirst over the handlebars at low speeds, or at higher speeds, to become a head-first missile. Indeed, there is even a specific term for flipping over the handlebars, an "endo" (i.e. end over end).
Recumbent cycles, on the other hand, protect the head, since the recumbent position places the cyclist in a laid back, reclining position, where they ride feet-first. In the event of a crash, the cyclist can much more easily absorb at least part of the impact by bending their legs. Additionally, the recumbent position distributes the weight of the cyclist differently, meaning an "endo" is virtually impossible, allowing much more aggressive braking on the front wheel.
While there are a diversity of recumbent designs, in general recumbent cycles do position the cyclist with a lower profile than diamond frame bikes. This can raise concerns about visibility in traffic, particularly for those who ride recumbent trikes, whose center of gravity is low out of necessity.
Many recumbent cyclists emphasize their ability to make eye contact with drivers on the road as important to staying visible and being part of traffic, which is facilitated by the "heads-up" recumbent position. Even recumbent trike riders sit at a height that is similar to sports car drivers and most drivers of economy sedans, which are the majority of cars on the road.
More important is the fact that recumbent cyclists consistently report that they are given far more room on the road than they are when they ride diamond frame bikes. The fact is that drivers notice recumbents in a big way, and generally give them a wide berth.
However, there are some situations, such as in parking lots, when a low profile can be problematic. To make themselves more visible, recumbent cyclists often use visibility aids such as flags mounted on poles. For all of our recumbents with a low profile, Ergo Cycle provides a flag and flagpole. Another major benefit of recumbent cycles concerns aerodynamics. Because the traditional diamond-frame bike places the cyclist in an upright position, much of the cyclist’s body acts as a parachute. On the other hand, the recumbent position reclines the cyclist behind their feet, meaning they can more efficiently “slide” through the air without generating as much wind resistance. This is the reason that all current human-powered vehicle records have been set on fully-faired recumbent bicycles- because this is the most aerodynamic set-up.
However, even for cyclists who are not interested in speed, a few rides on a windy day might convince one of the value of good aerodynamics.
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