Classification of bikes (3)

Introduction

Why the sudden interest in the classification of bikes?

bikes-sch-30 for blog

The AASHTO Green Book (ref. 831) says that:

Key controls in geometric highway design are the physical characteristics and the proportions of vehicles of various sizes using the highway.

And that

“the bicycle should also be considered as a design vehicle where bicycle use is allowed on a highway”

The Los Angeles bicycle plan, technical design handbook (ref. 917) has this to say on the subject:

Similar to motor vehicles, bicyclists and their bicycles come in a variety of sizes and configurations. This variation can take the form of a conventional bicycle, a recumbent bicycle, a tricycle, or the behavioral characteristics and comfort level of the bicyclist  riding the device. Any bikeway undergoing design should consider the various types of bicycles that may be expected on the facility and design with that set of critical dimensions in mind.

Whilst a UK document on cycle infrastructure design (ref. 745) says:

… there is a great variety of types (of bicycle) in use. Designers should anticipate the use of non­standard cycles, particularly in areas with high levels of utility cycling, on recreation routes and on routes serving schools and nurseries. Designing to accommodate tandems, tricycles and trailers opens up cycle routes to families with children and users of hand­cranked cycles.

The argument is then that, to design roads for bikes an engineer needs to know the size of bikes, and that the size of bikes varies with the type (or class). For example, a standard bicycle may be 1.78m long, but a bicycle with child trailer can be 3.05m long (see table 1).

bikes 3a

Can bikes be larger than cars?

It can be a mistake to think that bikes are smaller than cars. For example, the length of a bicycle with child trailer may be 3.05m, but the length of Toyota’s iQ is only 2.985m. Table 2 compares the dimensions of a VW Golf car with different types of bike. It shows that bikes can be longer and higher than cars.

bikes 3b

Driver eye height

Sight distance is one of the important parameters used in highway design. It is dependent (amongst other things) on the height of the driver’s eye above the road surface.  The higher the driver eye height is, the better is his sight distance. Table 3 shows that whilst the eye height of a bicyclist on a standard bike is higher than the recommended figure for a car driver, the eye height of a recumbent bicyclist is lower – and for the rider of a velomobile, it can be quite a bit lower (a velomobile is the bike world equivalent of a sports car).

bikes 3c

Another way to classify bikes – by function

The AASHTO reference establishes “four general classes of design vehicles”:  (1)  passenger  cars,  (2)  buses, (3) trucks, and (4) recreational vehicles. It then gives dimensions for 20 design vehicles within these general classes. One German reference(ref. 622) gives dimensions for 4 classes of vehicle (private cars, lorries, buses and refuse vehicles) with a total of 13 design vehicles for these classes. These two references classify motor vehicles by function (buses, goods vehicles etc). Perhaps bikes can also be classified by function.

bikes 3d

References

622  – Germany, Bemessungsfahrzeuge und Schleppkurven zur Überprüfung der Befahrbarkeit von Verkehrsflächen; fgsv (2001)

745  – UK, Local transport note 2/08 “Cycle infrastructure design”, DTp (2008)

831  –  USA, AASHTO, A policy on the geometric design of highways and streets (2011)

917  – USA, Los Angeles 2010 Bicycle Plan, technical design handbook, USA (2011)

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About roadnotes

Robert Bartlett is an international consultant with over 30 years of professional experience as a highway and traffic engineer with leading companies and organisations in several countries, including Germany, China (Hong Kong), Qatar and the UK. Specialised in urban studies, transport and the use of GIS, research has included new ideas on subjects such as the study of social justice using GIS, the dimensions of vehicles, and comparative geometrics (highways and transport).
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2 Responses to Classification of bikes (3)

  1. Bill Chance says:

    What’s really important is the skill and confidence of the rider – the speed and ability to handle an interface with traffic. Bikes can vary from pedestrian-like to almost as fast as a car (in an urban setting) and everything in between.

    Interesting ideas, thanks for sharing.

  2. I like the valuable info you provide in your articles.
    I’ll bookmark your blog and check again here regularly. I’m quite certain I will learn many new stuff right here!
    Best of luck for the next!

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