Be careful! Children's feet might be caught in the wheel while double riding; Bicycle spoke injuries have frequently occurred

Purpose

It has been often reported that a person sitting on the rear of a bicycle with or without a child bike seat got his/her foot caught in the rear wheel and was injured while double riding, so called "a bicycle spoke injury". The Medical Facilities Network received 172 reports of such injuries in the past five years. In 91 cases of them, i.e. more than half, the injured needed to go to hospital. In 90 cases, i.e. more than half, the injured were children under the age of six who were carried on a bicycle. Children are prone to bicycle spoke injuries, and sometimes could be seriously injured.

As a result of questionnaire survey among 2,000 consumers aged 20-69 who had carried their child or acquaintance on a bicycle, it was found out that risk of a bicycle spoke injury becomes higher if a child bike seat is not used.

Therefore, the National Consumer Affairs Center of Japan conducted a series of tests concerning bicycle spoke injuries based on cases received by the Medical Facilities Network ¹ and the result of questionnaire survey, and decided to issue an alert to consumers and provide information concerned.

1. ¹ The Medical Facilities Network is a joint project by the Consumer Affairs Agency and the NCAC, which started operating from Dec. 2010. The network collects accident reports on people receiving treatment at medical facilities after suffering life-threatening or bodily injuries in their daily lives.

What is a bicycle spoke injury?

Spokes are thin bars or long straight pieces of metal that connect the center (hub) of a wheel to its outer edge (rim) on a bicycle (See Photo 1). A bicycle spoke injury is experienced when a leg is caught in spinning spokes. It occurs when a leg of a passenger on the bicycle rear (with or without a child bike seat) is trapped in the rear wheel.

Photo 1. Spokes of a wheel

Cases of bicycle spoke injuries reported to the Medical Facilities Network

More than half of the injured needed to go to hospital. Injuries of foot (the lowest part of the leg below the ankle) were most common.

The Medical Facilities Network received 172 reports ² of bicycle spoke injuries (while double riding, a leg of a passenger was trapped in bicycle spokes) in the past five years. Since FY2012, the number of such reports in a fiscal year has been around 30 (See Diagram 1). Bicycle spoke injuries mostly occurred when a leg was trapped in the rear wheel.

1. ² The data were registered from April 2011 through July 31, 2016. The number of cases was specially counted for this publication.

Diagram 1. Number of cases by fiscal year

The number of cases was: 49 in FY2011, 30 in FY2012, 26 in FY2013, 29 in FY2014, 29 in FY2015, and 9 in FY2016 (till July).

Diagram 2. Breakdown of cases by required level of treatment (n=172)

Hospital visit was required for 91 cases (52.9%). Hospital visit was not required for 60 cases (34.9%). Hospital stay was required for 1 case (0.6%). Unknown cases were 20 (11.6%).

Diagram 3. Breakdown of cases by age group (n=172)

Among the 172 injured persons, 90 persons (52.3%) were under 6 years old. 76 persons (44.2%) were 6-11 years old. 6 persons (3.5%) were 12 years old or more. Among the 90 cases where a child under 6 years old was injured, a child bike seat was not used in 35 cases (38.9%). A child bike seat was used in 12 cases (13.3%). Unknown cases were 43 (47.8%).

Diagram 4. Breakdown of cases by injured area (n=172)

Foot excluding toes got injured in 153 cases (89.0%). Thigh or lower thigh got injured in 11 cases (6.4%). Toes got injured in 2 cases (1.2%). Unknown cases were 6 (3.5%).

Cases where a child bike seat was not used

[Case1]

When a boy was sitting on a rear carrier of a bicycle owned and ridden by his relative, his left heel was trapped in spokes. The bicycle was a typical granny's bike and did not have a child seat or a dress guard to prevent entanglement.

(received in June 2011, four years old boy, moderate injury)

[Case2]

When a girl was sitting on a rear carrier of a bicycle ridden by her father, her left leg was trapped in spokes of the rear wheel. There was a laceration (4cm in diameter, 2cm in depth) on the rear surface of her left leg joint. She was treated in an emergency department. Her dermis and epidermis were sutured.

(received in September 2015, five years old girl, moderate injury)

[Case3]

A boy was straddling a rear carrier of a bicycle ridden by his father. Since it was a short distance, he did not use a child bike seat. The boy got injured when his left leg was trapped in sporks. He was wearing Japanese sandals on bare feet. There was a fan-shaped laceration spread from the root of Achilles tendon, which was so deep that a tendon can be seen. He had twelve stitches.

(received in October 2015, five years old boy, mild injury)

Cases of problematic use of a child bike seat

[Case4]

A boy was sitting on the rear of a bicycle ridden by his mother. On the way to go shopping, his left leg was trapped in the rear wheel. A child bike seat was installed on the rear of the bicycle, but the boy did not place his feet on the footrest properly. He got scratches at left ankle joint.

(received in March 2011, four years old boy, mild injury)

[Case5]

A seven years old girl was sitting on a child bike seat on the rear of a bicycle ridden by her mother. The girl got injured when her right leg was trapped in the rear wheel.

(received in May 2011, 7 years old girl, mild injury)

[Case6]

I went to a kindergarten to fetch my son by bicycle. I made him sit on a child bike seat on the rear of a bicycle without helmet and belt. The footrest of the child bike seat was lost, but I thought it was OK because my son grew up to some extent. While riding, however, his left heel was trapped in the rear wheel.

(received in November 2011, six years old boy, mild injury)

[Case7]

I made my daughter sit on a child bike seat, the footrest of which was broken. Her left foot was placed on a metallic frame of the bicycle while riding, but the foot slipped off and was trapped in the rear wheel. She got a laceration at the left heel, a sprain of the left ankle, and subcutaneous hematoma.

(received in February 2013, seven years old girl, mild injury)

Questionnaire survey

A questionnaire survey was conducted among 2,000 consumers aged 20-69 who had given a child or acquaintance a ride on a bicycle.

Of these consumers, 252 persons experienced that their passengers had been trapped in spokes. More than half of the passengers were six years old or more.

Diagram 5. Breakdown of entangled passengers by age group (n=252)

103 persons (40.9%) were under 6 years old. 91 persons (36.1%) were 6-11 years old. 58 persons (23.0%) were 12 years old or more.

The lowest part of the leg below the ankle, particularly left side, was most prone to be trapped.

Diagram 6. Breakdown of entangled passengers by trapped area (n=252)

Left ankle and below was trapped in 133 cases (52.8%). Right ankle and below was trapped in 56 cases (22.2%). Left kneecap and below was trapped in 29 cases (11.5%). Right kneecap and below was trapped in 33 cases (13.1%). Other area was trapped in 1 case (0.4%).

Nearly 60% of the injured required one week or more to make a full recovery. More than one year was reguired for 13 persons.

Diagram 7. Breakdown of the injured by full recovery period (n=214)

Among the 214 injured persons, 87 persons (40.7%) required less than a week. 69 persons (32.2%) required from 1 to 2 weeks. 37 persons (17.3%) required from 3 weeks to 1 month. 8 persons (3.7%) required from 1 month to 1 year. 13 persons (6.1%) required 1 year or more.

Use rate of child seats on the rear among entangled passengers was smaller than that among those not entangled.

Diagram 8. With or without a child bike seat on the rear

Among 948 passengers under the age of six, 103 passengers were entangled. Among the 103 passengers, 58 (56.3%) passengers were seated on a child bike seat, while 45 passengers (43.7%) were directly seated on the carrier without a child bike seat. Among 845 passengers who were not entangled, 662 passengers (78.3%) were seated on a child bike seat, while 141 passengers (16.7%) were directly seated on the carrier without a child bike seat. Other cases were 42 (5.0%).

Among those who experienced that their passengers had been trapped in spokes, the ratio of bicycles without dress guard was larger than that among those who did not experience it.

Photo 2. Example of a dress guard

Diagram 9. With or without a dress guard

Among 103 persons who experienced entanglement, 28 persons (27.2%) used a dress guard, while 61 persons (59.2%) did not use a dress guard. Unknown cases were 14 (13.6%). Among 845 persons who did not experience entanglement, 486 persons used a dress guard (57.5%), while 217 persons (25.7%) did not use a dress guard. Unknown cases were 142 (16.8%).

Simulation experiment

(1) Cases without a child bike seat and a dress guard

When neither a child bike seat nor dress guard was installed, some of the passengers got their feet (between heel and Achilles tendon) strongly trapped in the rear wheel.

According to the cases received by the Medical Facilities Network and the questionnaire survey result, it appears that risk of bicycle spoke entanglement becomes higher when a child is seated on the carrier of a bicycle without a child bike seat and a dress guard. When a child was seated on the carrier during the simulation experiment, the feet sometimes moved closer to the wheel (See Photo 3).

During the simulation experiment of bicycle spoke entanglement for which a 5-6 years old child dummy was seated on the carrier (See Photo 4), the area between the heel and Achilles tendon was sometimes strongly trapped in spokes of the rear wheel as soon as the leg of the dummy touched the wheel (See Photo 5).

Photo 4. Foot getting trapped in the wheel

Photo 5. Area between heel and Achilles tendon trapped in the wheel

(2) When a child aged six or more was seated on a child bike seat

Even with a child bike seat, children aged six or more are at high risk of being trapped in the wheel.

Child bike seats are intended to be used by children under the age of six. If a child aged six or more sits on a child bike seat, movement of legs cannot be properly restrained due to size mismatch, as a result of which legs are prone to be trapped in spokes. When legs of a child aged six or more were removed from the footrest and dangled, legs sometimes moved closer to the wheel (See Photo 6).

Standard for child bike seats; whether or not it is allowed to carry two children on a bicycle under the traffic rules

The SG standard specifies that child bike seats shall be designed to keep some distance between legs and the wheel to prevent legs from being trapped. Under the traffic rules, a child under the age of six may only be seated on a child bike seat.

The SG standard ³ specifies that child bike seats shall be designed to keep some distance between legs and the wheel by restraining inward, backward and forward movement of legs on the footrest so that legs will not be trapped in the wheel (See Photo 7). If a footrest is damaged or deformed, the product cannot protect a child properly.

Under Japan's traffic rules, only one child under the age of six may be seated on a bicycle with a child bike seat ridden by a person aged 16 years or more. In case of a bicycle for carrying two children, two children under the age of six may be seated on two child bike seats, one for each.

1. ³ SG standard for Child Carriers for Bicycles (CPSA0070) set by the Consumer Product Safety Association

Photo 7. Footrest

Advice for consumers

(1) Always use a child bike seat when a child under the age of six is carried on a bicycle.

The SG standard specifies that child bike seats shall be designed to keep some distance between legs and the wheel so that children's legs will not be trapped in spokes of the wheel. Always use a child bike seat when you carry a child under the age of six on a bicycle to prevent his/her legs from being caught in the wheel.

A dress guard is also effective for preventing bicycle spoke entanglement. It should be used together with a child bike seat. Remember to make a child wear a seat belt and a helmet. Before installing a child bike seat on the carrier, be sure to check an instruction manual, whether or not it is possible to install it on your bicycle, classification according to weight, and whether or not it is a double side stand.

It would not be possible for a damaged or deformed child bike seat to fully prevent bicycle spoke entanglement. Never use a child bike seat which appears to be damaged or deformed. It is against the traffic rules to carry a child under the age of six on a bicycle without using a child bike seat.

(2) Children aged six or older are more prone to bicycle spoke entanglement; they should not be carried on a bicycle.

It has been reported many times that a child aged six or more was seated on a bicycle and his/her leg was trapped in spokes of the wheel. The SG standard specifies that child bike seats shall be used by children under the age of six. If a child aged six or more is seated on a child bike seat, his/her legs will not be fully prevented from being trapped in spokes due to size mismatch. Never misuse a child bike seat. Improper use may cause damage or deform of a child bike seat.

Incidentally, it is against the traffic rules to carry a child aged six or more on the rear of a bicycle, regardless of use of a child bike seat.

Request to businesses concerned

NCAC requests businesses concerned to further raise awareness of consumers to ensure use of a child bike seat when a child is carried on a bicycle.

It has been reported many times that a child was seated on a bicycle carrier and his/her leg was trapped in spokes of the wheel. NCAC requests businesses concerned to further raise awareness of consumers to ensure use of a child bike seat as well as a dress guard when a child is carried on a bicycle.