Injuries associated with failure or malfunction of bicycle parts

Disclaimer:

This report was written in response to a specific inquiry from one of NISU's clients. It makes use of available data and should not be viewed as a detailed piece of research. NISU releases this information in the interest of ensuring that work done for one client can inform others. The report must not be quoted or cited without the written permission of NISU.

Introduction

The information contained in this report has been derived from the Injury Surveillance Information System (ISIS). ISIS is an injury database maintained by the National Injury Surveillance Unit. It contains records of emergency department attendances drawn from a sample of approximately 50 Australian hospitals since 1986. The ISIS system is well suited for characterising the circumstances of individual and similar groups of cases. It is not, however, amenable to accurately describing the incidence of particular types of injury in the population due to biases arising from the mix of participating hospitals.

There was a total of 1,083 cases of injury in the database in which a bicycle part was reported to have failed or malfunctioned. In order to determine which parts were problematic, it was necessary to scutinise the individual case descriptions - a random sample of 229 cases (22 per cent) was selected for this purpose, being a sufficient number to allow description of the major problems. The following account is based on the sample of 229 cases.

It should be borne in mind that information is reported by the injured person or their reprentative at the time of attendance in the emergency department. Thus, reports of failure or malfunction have not been objectively validated. Nonetheless, the information obtained is useful in that it reveals the types of problems and difficulties that can arise. Some of these may indeed be examples of genuine product failure, while others may indicate opportunities to improve product designs.

Age and sex of injured persons

As might be expected, children are at greatest risk of being injured. The most common age-group reporting injury in this sample of cases was the 10-14 years group (Table 1). This age-group is known to be the highest risk group for bicycle related injury. The excess risk probably attributed to an increase in exposure to bicycling at this age, in combination with a relative inexperience of handling unfamiliar situations. This latter factor may be particularly important for some of the problems that will be described below. For example, coping with a chain coming off a bike may be beyond the capabilities of an inexperienced rider whereas it poses little difficulty for a more experienced rider.

CHILD CASES (0 TO 14 YEARS)

Age group	Number	Per cent
0-4	4	2.3
5-9	37	21.4
10-14	132	76.3
Total	173	100.0

ADULT CASES (15 OR MORE YEARS)

Age group	Number	Per cent
15-29	49	87.5
30-44	4	7.1
45-59	2	3.6
60-74	1	1.8
Total	56	100.0

For both child (0 to 14 years) and adult (15 or more years) cases, the sex distributions were identical: eighty-two per cent male, 18 per cent female.

Location of injury

Most of the injuries took place on public roads (72 per cent), where there is great potential for conflict with motor vehicles and other road users. Around five per cent of cases occurred on footpaths and a further five per cent in a private yard or garden.

Severity and type of injury

An indication of the severity of these injuries is given by the level of treatment that was obtained at hospital. The disposal patterns for child and adult cases were fairly similar, although there was an indication that child cases more frequently required significant treatments and admission.

Cuts and lacerations were the most commonly reported injury (22 per cent of cases), followed by fractures (21 per cent), bruising (17 per cent), abrasions (17 per cent), dislocations (7 per cent) and concussion (7 per cent). The upper extremities were the most frequently injured body part (58 per cent of cases), then came the head (33 per cent), lower extremities (32 per cent) and trunk (8 per cent).

Part associated with failure

The descriptions of the events leading to the injury were scanned and classified according to the part of the bike that was reported to have malfunctioned or failed. The distribution of these parts is presented below:

Part of bicycle	N	Per cent
Chains / gears	78	34.1
Brakes	72	31.4
Wheels	41	17.9
Handlebars	14	6.1
Pedals / cranks	7	3.1
Saddle	1	0.4
Other	16	7.0
Total	229	100.0

Chains

The most common mishap involving chains was them coming off while the bicycle was in use. Chain breakage was also reported. These events often led to a loss of control of the bicycle with subsequent collisions with other objects. The frequency of this mishap suggests that attention to the design of chains and gear mechanisms to lessen the occurrence of slippage is warranted. It may be that children's bicycles need more scrutiny in this regard than adult bicycles.

Brakes

While many of the cases that reported brake failure seemed to involve events such as brakes locking up and drastic application of front brakes causing the rider to fall forwards and off the bike, and therefore are not strictly cases of failure, there is an obvious concern that children are having difficulty in correctly operating the brake mechanisms fitted to their bikes. Further research is necessary to establish the most appropriate braking mechanisms for children's bicycles - this may for example involve only fitting rear wheel brakes. More attention is needed in properly educating young cyclists on the correct application of brakes, as is attention to proper maintenance of brake pads and cables. Brake cables were reported to get snagged in the front wheel and this situation may be able to be rectified by improved product design.

Wheels

Wheels often fell off bicycles, most frequently the front wheel. This problem may require careful investigation of the assembly of bicycles, particularly the structural integrity of frame joints and bearings. The fitting of after-market parts such as forks, headstems, and handle-bars may affect the safety of bicycles, and the safety of these products should also be considered.

Handlebars

The problems here were several: breakage of handlebars; loosening of handlebar assemblies; and handle grips falling off. As with all the other parts considered above, failure can have very severe consequences due to loss of control of the bicycle in traffic streams. Consideration of safety standards for each of these situations may be required.

Pedals and cranks

There were a number of instances of structural failure of these parts, suggesting that attention be given to the material strength of these parts.

Summary

The various problems identified in this report with chain assemblies, brakes, wheels, handlebars and grips, and pedals all pose significant safety hazards to young bicycle riders. The severity of the threat is important because loss of control of the bicycle can lead to collisions with other motor vehicles, as well as high speed collisions with the ground and other objects. Further research is needed to investigate the mechanisms underlying these apparent product failures and malfunctions. For example, the extent to which these problems apply to new bicycles as opposed to older bicycles, and the relative contribution of inadequate maintenance cannot be determined unless in-depth investigations are undertaken.

Summary descriptions of the events leading to injury are available here. These are grouped according to the part which reportedly malfunctioned or failed:

• BRAKES
• WHEELS
• CHAINS OR GEARS
• PEDALS
• HANDLEBARS
• SADDLE
• OTHER