Posted at: Apr 12, 2023
Rearview radar for road bikes are important accessories that increase safety when cycling. The following is a summary of their advantages and disadvantages and a comparison of specifications of major products.
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A road bike rearview radar is a “proximity sensing sensor” that is mounted on the rear of the bicycle.
Its main role is to detect the approach of a vehicle passing from behind and notify the rider. This is expected to enhance safety when riding and contribute to the prevention of traffic accidents.
In automobiles, functions to recognize approaching vehicles, such as rear cameras and corner sensors, are increasingly being installed as standard equipment. In bicycles, however, this accessory is still not widely used, but it has gradually gained recognition in recent years.
The advantage of a rearview radar is that it can properly detect hazards.
Unlike cars and motorcycles, road bikes are not often fitted with side mirrors, and rearward checking is done by looking backward. This in turn tends to make people inattentive to the road ahead, so it is normal for road bikers to check behind when changing lanes or turning.
This leaves them vulnerable to vehicles approaching when they are not looking backward, but by installing a rearview radar. Rear view radar allows them to constantly check their rearward position and the rider can see approaching vehicles on the cycle computer.
Rearview radar also work effectively at night and in bad weather, so they have the added benefit of enabling safe rearward checking even in poor visibility conditions.
Although rearview radar make road bike riding safer, the biggest disadvantage is that they are not completely reliable.
If a vehicle approaching from behind is fast or if there are many vehicles around, there may be a delay in the sensor’s response. Therefore, the use of rear sensors does not eliminate the need to check the rear of the vehicle, but only to provide support.
In addition, a rearview radar is meaningless on its own and must be used in combination with a cycle computer or smartphone. The rearview radar alone costs more than $100, and if you also need a compatible cycle computer, you will be investing several hundreds dollers.
It is up to the individual to decide if he or she should invest in an “expensive bicycle accessory that does not work perfectly.
The performance of a rearview radar is determined by its “detection range” and “detection accuracy.
Naturally, the wider the detection range and the higher the accuracy, the higher the performance of the rearview radar.
On the other hand, if the detection range is narrow or the accuracy is low, “the car was already approaching when the sensor detected it”, and accidents and dangerous situations cannot be avoided. This makes it meaningless to install rear sensors.
The detection range of rear radar is determined by the “sensing distance” and the “radar’s vertical and horizontal range angles. The longer the sensing distance, the better, and the wider the range angle, the better the accuracy of detection on curves and other non-straight lines.
Since the rearview radar is basically attached to the seat post, it does not warn on its own, but rather on a display linked to a cycle computer or other device. Depending on the linked device, there are different warning methods, such as vibration, flashing lights, and audio alerts, but they are meaningless if the warning is not understood.
Cycle computers may display the detection signal on the vertical side of the screen, or a cycle computer with LEDs may use LEDs to notify you, but you should decide which is easier for you to see according to your style.
Also, make sure that your cycle computer or smartphone can be paired with a rearview radar. Basically, you will connect with either ANT+ or Bluttooth, but some products can only be connected with either, or the cycle computer may not support rearview radar.
Since rear sensors are battery-operated, “how long they last” is also very important. Especially on long rides, it will be stressful if the battery runs out in the middle of the ride, so choose a model with as long a battery life as possible.
If you are going to use it for long rides, you should choose a rear sensor that can be used for more than 10 hours.
| Product | Sensing Distance | Range Angle | Battery Time |
|---|---|---|---|
| Garmin Varia Rear View Radar RTL510 | 140m | Non-public | up to 15 hours |
| Bryton GARDIA R300L | 190m | Non-public | up to 17 hours |
| Magene Radar Rear Light L508 | 140m | up to 40° | up to 16 hours |
Garmin’s Varia is the standard for rearview radar for road bikes, currently available its 3rd generation RTL515 and the lower-priced RVR315. The second generation RTL510 has been discontinued by the manufacturer and is only available from market stock.
The main appeal of Garmin Varia is the high accuracy and peace of mind that comes from Garmin, a long-time manufacturer of sensors for commercial and private use, and its compatibility with cycle computers.
The Edge series of Garmin cycle computers as well as most cycle computers that support backward sensors are compatible with Garmin Varia, so there is the advantage of not having to choose a cycle computers.
The difference between RTL515 and RVR315 is the presence or absence of a tail light and the operating time. This difference is probably reflected in the price.
However, as for operating hours, RVR315 has only 7 hours of operation, so for long rides that run all day, RTL515 is the best choice.
The GARDIA R300L is a rearview radar released in 2023 by Bryton, which also competes cosmetically with the king of cycle computers, Garmin.
The biggest advantage of this product is that it is $80 cheaper than its rival, Garmin’s Varia RTL510, and can be purchased for less than $200. It is also higher than Garmin’s Varia RTL510 in terms of performance, with a maximum sensing distance of 190 meters and a battery life of up to 17 hours.
Although this is a new product to the market, it is a rearview radar from Bryton, which has a certain reputation for cycle computers, so there is a sense of security.
This rearview radar is from Magene, a Chinese manufacturer of inexpensive power meters, cycle computers, and smart trainers.
The affordable price is typical of Chinese manufacturers, and a high-performance rearview radar can be obtained for less than $200. Some products are sold for as low as $140 at overseas retailers, making them a good first choice if you are looking for a low-priced product anyway.
This rearward radar is produced by IGPSPORT, a Chinese manufacturer that is also a popular manufacturer of cycle computers.
The advantage of SRTL SR30 is that it has almost the same specifications as competing manufacturers and is priced in the $100s.
It is compatible with iGPSPORT’s iGS630 and BSC300 cycle computers.
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