Indicators on bicycles have been a hot topic of debate for a long time. For two years now, they have not only been legally permitted in Germany, but also available to purchase in bicycle shops. Busch + Müller, for example, was quick to offer a solution that could be fitted to ebikes with its Turntec T4 system. Now, with Turntec T2, the manufacturer is launching its next indicator set onto the market. This raises the question of which one comes out on top in a direct comparison.
1. Basic information about indicators on ebikes
2. Compatibility: Busch & Müller Turntec T2 the set for everyone
3. Usability: Busch & Müller Turntec T4 scores with control unit
4. Visibility: Four indicators are better than two
5. Light duration: When the motor is running, the Busch & Müller Turntec T4 flashes
6. Workmanship: Different requirements = different materials
7. Mounting: Busch & Müller Turntec T2 quick to install
8. Price: No system a real bargain
9. Conclusion: Busch & Müller Turntec T2 and Busch & Müller Turntec T2 closely matched in comparison
1. Basic information about indicators on ebikes
The 19th of June 2024 marks a turning point in Germany. That sounds dramatic. But a little drama seems appropriate here. After all, protagonists of pedal-powered mobility have tirelessly championed the advantages of indicators on bicycles for many years – and have repeatedly come up against a brick wall with their arguments. On that summer day, however, the 56th Ordinance Amending Road Traffic Regulations for the Road Traffic Licensing Regulations (StVZO) listed directional indicators as permitted for all types of bicycles for the first time. The exact regulations can be found in § 67 ‘Lighting equipment on bicycles’ of the StVZO.
Sadly, it was ultimately the rising number of accidents involving ebike riders that prompted the federal government at the time to reconsider its position. It too apparently understood that people ride bicycles more safely when they can keep both hands on the handlebars to signal when turning. This can significantly increase the feeling of safety on an ebike or bicycle, especially on slippery, wet or very bumpy roads. Especially in the dark, at dusk or in poor visibility conditions, all other road users also benefit from the highly visible flashing signal.
The legal basis for the Busch & Müller Turntec T2 and the Busch & Müller Turntec T4 is therefore identical. However, the rest of this article will highlight the major differences between the two systems.
2. Compatibility: Busch & Müller Turntec T2 the set for everyone
The Busch + Müller Turntec T2 is a indicator that you can use on both ebikes and bicycles without electric motor assistance. It is powered by its own battery, which fits into the handlebar tube. The two indicators that come with the system are mounted on the left and right of the handlebars. This theoretically even paves the way for switching from use on a conventional bicycle to an ebike and back again – for example, for those who like to ride one vehicle for part of the year and then switch to the other vehicle for the rest of the year.
The Busch + Müller Turntec T4 does not offer the same option. Designed exclusively for ebikes, the set is intended for permanent use in conjunction with an ebike motor. Ebike systems with an operating voltage between 10 volts and 48 volts are suitable. At peak times, the indicators require two watts of power from the ebike system. Busch + Müller offers variants specially designed for installation on the Bosch Smart System. For other e-drives, the connection can be made via the lighting system using Y-Scotchlok connectors.
3. Usability: Busch & Müller Turntec T4 scores with control unit
Busch + Müller obviously wanted to reduce the Turntec T2 to the essentials. That’s why the manufacturer has equipped the indicators with a ring-shaped button. This allows you to take your palm off the handlebar grip while riding and briefly press the ring button with your palm. Pressing the button triggers the indicator signal.
In contrast, the Busch + Müller Turntec T4 includes a separate control unit with two arrow keys. It can be placed on the handlebar next to the left handlebar grip. When you press one of the buttons, the arrow on the respective button flashes and confirms the flashing process. If you press the left button, the left front and rear indicators light up; if you press the right button, both indicators on the right side of the ebike light up.
Configurable flashing modes
T2 and T4 support two main flashing modes. In standard mode, the indicator flashes 15 times when you press it once. This is the default setting. You can also change the number of flashes afterwards, from a minimum of five to a maximum of 30. Pressing and holding the ring button on the T2 or one of the arrow buttons on the T4 triggers the four-minute comfort flashing mode. Pressing the button again ends this mode early to save power. Comfort flashing is useful if, for example, you are waiting at a traffic light intersection in a turning lane and want to indicate your intention to turn during a longer traffic light phase.
For emergencies, the Busch + Müller Turntec T2 and Busch + Müller Turntec T4 also feature a hazard warning mode. This is activated by pressing both ring buttons simultaneously for three seconds or both arrow keys for 1.5 seconds. Each subsequent press of the button ends the warning mode.
4. Visibility: Four indicators are better than two
Thanks to their position at the ends of the handlebars, the Turntec T2 indicators are clearly visible. Often, these two points define the width of an ebike or bicycle – at least when we are talking about flat handlebars, riser handlebars, moustache handlebars or butterfly handlebars. You usually hold the handlebars by the handlebar grips. This means that the indicators are not covered by your hands or other components.
To prevent the indicators from being damaged when the bicycle is parked, the manufacturer has protected them with a housing. Its large openings ensure that plenty of light can still be emitted to the front and rear.
The number of indicators alone illustrates where the Turntec T4 is superior to the Turntec T2. Four indicators are twice as many as two, quite simply. Visibility is therefore the major advantage of this system, which is explicitly designed for ebikes. The two front indicators are mounted on the handlebars approximately at the same height as the brake levers. The rear pair usually uses a bracket on the rear rack. They can either protrude from the side next to the tail light or extend to the left and right of the rear rack. With their 180-degree opening in the appropriate direction, the Turntec T4 indicators are highly visible, regardless of whether another vehicle or a pedestrian is approaching from the front or rear.
5. Light duration: When the motor is running, the Busch & Müller Turntec T4 flashes
To serve as a solution for ebikes and bicycles without electric drive, the Busch + Müller Turntec T2 comes with its own battery. The product data sheet does not indicate how long this allows for flashing. Upon request, the manufacturer promises ‘about two months with good use’. Unfortunately, there is no way to see how much capacity is currently left in the system. However, the system is supposed to flash faster as soon as the remaining capacity is less than ten percent.
You can charge the battery in the handlebar tube using a USB-C socket on the left indicator. You can use any existing charger for this. Its performance ultimately determines the actual charging time. A red LED light illuminates on the indicator during charging. When this light goes out, the battery is fully charged.
Charging is only necessary with the Busch + Müller Turntec T4 when the ebike’s battery needs power. Until then, it supplies the indicator system with energy. In theory, you can therefore use it indefinitely. Thanks to the connection to the light port, the indicators still work even when the battery is so depleted that it uses its emergency reserve and switches off functions such as motor assistance and electronic gear shifting in order to save the remaining power and ensure your safety on the ebike.
6. Workmanship: Different requirements = different materials
As is usual with Busch + Müller, both indicator systems appear to be of high quality. The Busch + Müller Turntec T2 is enclosed in a robust aluminium housing. This material, which is often used in lightweight construction, ensures a low total weight of 165 grams.
The manufacturer uses plastic much more frequently in the Busch + Müller Turntec T4. This is required by certain functions and properties of the system. For example, the two rear indicators are attached to flexible mounts. These give way even with slight resistance. So if you get caught somewhere with the indicator or bump into something, it won’t break off immediately. Plastic is a good material for meeting this requirement. Weighing 275 grams, the solution with four indicators is quite light as well.
7. Mounting: Busch & Müller Turntec T2 quick to install
The universal indicators are very easy to install without any special tools. The only important thing is that the outer diameter of the handlebars measures between 17.5 millimetres and 19.5 millimetres. This is how much space you need to be able to insert the indicators into the handlebar tube. Finally, tighten a knurled nut by hand – and you’re ready to use the Busch + Müller Turntec T2.
Front indicator with mounting arm and clamp. Rear indicator with adapter for tail light mounting. Control unit. Two-piece wiring harness. Cable ties. A quick glance at the contents of the package is enough to see that installing the Busch + Müller Turntec T4 is much more complex. Understandably, the manufacturer recommends installation by a specialist workshop.
For example, the minimum distance between both front indicators and the headlight is specified. The same applies to the distance between the rear indicators. You can combine the set with a tail light, but you don’t have to. In addition, there is the two-piece wiring harness. According to the manufacturer, it is so large that its distribution points have to be mounted externally on most ebikes. Specialist knowledge is helpful here. In any case, it takes more time to install the Turntec T2.
8. Price: No system a real bargain
At 124.90 euros, the Busch + Müller Turntec T2 costs as much as a high-quality battery-powered front light. Some of you might have hoped for a lower price. For the moment, though, it’s still well over 100 euros. From our point of view, this means it doesn’t count for one of those products that you happen to discover in a bike shop and buy on impulse. For others, however, the additional safety it offers may quickly justify the price. The first units are expected to go on sale in April 2026.
For an additional £75, you can get the specific flashing set for ebikes. It has been on the market for around two years at a price of £199.90. During this period, Busch + Müller has probably gathered enough information to estimate how much money prospective buyers would be willing to spend on a simpler version. Let’s see whether the two solutions inspire or undermine each other.
9. Conclusion: Busch & Müller Turntec T2 and Busch & Müller Turntec T2 closely matched in comparison
The Busch & Müller Turntec T2 is the better indicator for an ebike compared to the Busch & Müller Turntec T4 – if easy installation is important to you and you want the lowest possible price. It also blends in more discreetly with the ebike. In our opinion, it is a good solution for those who only want to use indicators occasionally.
For those who consider the system an indispensable feature of an ebike because they are looking for maximum visibility that is present as long as the ebike battery is supplying power, the Busch & Müller Turntec T4 seems to be the best choice. It is as fully-featured as an indicator on an ebike can currently be. On the other hand, the set costs more and requires considerably more expertise to install. You may have to leave the latter to a workshop and budget for additional costs.
Pictures: Busch + Müller KG