Bicycles today are fitted with highly effective braking systems. Regardless of their design, they deliver their best performance on dry roads. On wet roads, however, pedelecs with integrated ABS offer significantly improved braking performance. This was the finding of a series of comparative tests conducted by DEKRA Accident Research for the DEKRA Road Safety Report 2020.
- Comparison of different bicycle braking systems
- Braking performance on dry roads fulfills requirements for motor vehicles
- Conventional scooter offers virtually zero braking effect on wet roads
According to the legal requirements in Germany, for example, a bicycle must be fitted with two brakes operating independently of each other. While the regulation does not specify the design or any other characteristics, it states that the brakes must be permanently attached and capable of reducing speed to an adequate extent and securing the bicycle at a standstill. Similar requirements apply to e-scooters.
On the premises of the DEKRA Technology Center at the Lausitzring race track, DEKRA Accident Research tested the braking performance of modern bicycles, pedelecs and S-Pedelecs. The six test vehicles had earlier been used in everyday life. Before the test, their tire pressures were checked and the condition of their brakes was assessed. The following braking systems were fitted to the wheels:
- City bike: caliper brake at the front, backpedaling brake at the back
- Trekking bike: caliper brakes at the front and back
- Mountain bike 1: caliper brakes at the front and back
- Mountain bike 2: disk brakes at the front and back
- S-Pedelec: disk brakes at the front and back
- Pedelec: disk brake with ABS at the front, disk brake at the back
“The braking systems can be compared only when the tire-to-road contact surface is also similar, which is why racing bikes and ‘fat bikes’ were not included in the comparative test,” says DEKRA accident researcher Luigi Ancona.
The test scenario encompassed multiple braking procedures with each test bicycle on both dry and wet surfaces. At a speed of 25 km/h, an experienced test rider applied the brakes at full force down to a standstill. For the wet-road braking tests, the entire run-up and riding area as well as the braking area, the wheels and the braking systems themselves were thoroughly soaked with water to simulate the effect of rain as realistically as possible.
Differences more striking in wet-road performance
When it came to dry-road braking performance, all the test bicycles performed more or less equally well, with none of the different systems proving to be especially ineffective. But some still performed better than others. The bicycle fitted with the caliper and backpedaling brake combination required the longest braking distance (4.55 meters on average). The shortest braking distance – 3.66 meters – was achieved by the S Pedelec. This means that the difference between the best and worst performers was 89 centimeters.
On the wet road, however, the differences were much more striking. Here, too, the bicycle fitted with the caliper and backpedaling brake combination performed the worst, requiring a braking distance of 5.53 meters. The top performer was the ABS pedelec, which required a braking distance of 4.15 meters. So the difference between the best and worst performers in “rainy” conditions was 1.38 meters.
“In wet-road conditions, the braking distance required by all the test bicycles increased by around 20 percent – with the exception of the pedelec fitted with ABS,” says Luigi Ancona. “So on wet roads in particular, this system offers clear benefits.” In 2019, the Bosch eBike ABS received the DEKRA Award in the “Safety on the Road” category.
Deceleration rates of between 5.3 and 6.6 m/s² were recorded during the dry-road braking tests, which means that all the bicycles achieved the minimum deceleration rate of 5.5 m/s² required of motor vehicles. During the wet-road braking tests, the deceleration rates were between 4.4 and 5.8 m/s², so the ABS pedelec achieved the performance required of motor vehicles even in rainy conditions.
Brake tests also performed for e-scooters and conventional scooters
Using the same test setup, the DEKRA experts also performed brake tests with an e-scooter and a conventional scooter. The e-scooter was a model used by rental companies and fitted with two drum brakes; the conventional scooter was fitted with only one foot brake on the rear wheel, whereby a brake plate presses against the hard rubber tire. Both scooters were tested in wet and dry conditions and braked from a speed of 20 km/h.
On the dry road surface, the e-scooter required an average braking distance of 3.37 meters, equating to a deceleration rate of 4.6 m/s². With an average braking distance of 9.70 meters and a deceleration rate of 1.6 m/s², however, the conventional scooter performed abysmally. Even more shocking was the difference in wet-road performance. While the e-scooter performed almost identically, the foot brake on the conventional scooter delivered virtually zero braking effect, with the average braking distance doubling to 19.25 meters and a deceleration rate of just 0.8 m/s². According to Ancona, “It was actually much more effective in this case to slow down by dragging your foot along the asphalt.” “Conventional scooters, which are considered toys rather than vehicles, come with highly variable braking systems. This is something that everyone should definitely bear in mind when purchasing a scooter.”
On a positive note, the e-scooter provided excellent braking performance. “Both brake levers could be safely applied with maximum force. The braking procedures were highly stable and gave the rider peace of mind,” says the DEKRA expert, summing up the test.
The DEKRA Road Safety Report
The annual DEKRA Road Safety Report, which first appeared in 2008, focuses on a different topic every year. The 2020 report covers two-wheeled modes of transportation, with DEKRA experts examining road safety in relation to bicycles, pedelecs, e-scooters and motorcycles from a variety of perspectives. The report concludes with specific demands and recommendations regarding technology, infrastructure and the human factor.
The online portal at www.dekra-roadsafety.com contains not only the latest report but also more detailed information, including video of the brake tests. You can also download all the DEKRA Road Safety Reports as PDF files.
