I'm not entirely sure about the relevant legislation. However, as the question contains "deutch" I'll give the situation for Germany plus an update about Switzerland. I'd expect a) the situation to be sufficiently similar across other European legislations for practical every-day use.
Summary: IMHO everyone misbehaved: Car driver, OP, and in Germany also the convoy would have misbehaved. According to Swiss traffic law, there was no convoy. As OP mentions this was a ride to a protest, one may also consider that the organizers of that protest made a mistake: it would have been better to obtain convoy driving permit for a feeder ride or to include the feeder rides into the protest route and get the road temporarily closed for other traffic by the police (while I don't know for sure whether this is possible in Switzerland, I would be much surprised if it weren't). It may still be that the organizers were just underestimating the number of participants coming that route.
The convoy behaving themselves would have made it easier for the car driver to behave themselves (I leave this in here even if there are no civil convoys in Switzerland: the recommendation for [motor] bike group rides in the police letter below boils down to doing pretty much the same that German traffic law requires for convoys).
The car driver behaving would have made it easier for OP to behave themselves. OP behaving themselves would have made it easier to avoid further escalation.
Of course the polite, de-escalating and sensible thing to do would have been to provide a safe way for other traffic to pass unless this bulk of bikers was on that road for only a short distance. And to clearly communicate to the car drivers behind that a huge group of bikes is ahead and that measures have been taken to get everyone along in a speedy and safe fashion.
The more so, as according to the comments, this was indeed not an accidental happening of 300 bikes going in the same direction at the same time on the same narrow road, but people joining a larger protest/demonstration: this is a matter of (lack of) organization.
First of all, all road users have to behave themselves so that they don't endager anyone - this I expect to be case in all legislations. (In Germany, road users must not even hinder or iconvenience/burden anyone else more than neccessary. Also in Switzerland no hindering of others)
- The car driver must not start a dangerous passsing maneuvre, and
- similarly, the bike drivers have to refrain from performing dangerous maneuvres to force the car driver to stop or force them to stay behind.
Note that endangering yourself is not exempt (and one may argue that considering rescue work being a rather dangerous occupation you cannot endanger only yourself in road traffic).
What should have happened (Germany)
Now, a group of > 15 bikes in Germany (
> 10 bikes in Switzerland see below) bikes can form a convoy (§ 27 StVO).
The bike convoy in question would be 150 - 300 bikes long. We're thus talking here of a convoy length in the order of magnitude of 500 m without gaps, maybe twice as long with gaps.
- Thus, the convoy should have gone in suitable subgroups (Abteilungen) leaving gaps for cars to pass safely.
- Nevertheless, the car was not allowed to attempt breaking the closed convoy.
And of course, passing is allowed only if safe, regardless of whether there should have been better conditions for the car.
- The leader of the convoy is responsible for the convoy to follow rules. They should have made sure all convoy participants know the respective rules.
A second rule to consider here is § 29 StVO "Übermäßige Straßenbenutzung" (excessive road use).
(2) Veranstaltungen, für die Straßen mehr als verkehrsüblich in Anspruch genommen werden, [...] , bedürfen der Erlaubnis. Das ist der Fall, wenn die Benutzung der Straße für den Verkehr wegen der Zahl oder des Verhaltens der Teilnehmenden oder der Fahrweise der beteiligten Fahrzeuge eingeschränkt wird; [...] Veranstaltende haben dafür zu sorgen, dass die Verkehrsvorschriften sowie etwaige Bedingungen und Auflagen befolgt werden.
Events that use roads more than usual [..,] need a permit. This is the case if number or behaviour of participants or driving style restrict [normal public] road use. [...] Organisers have to ensure that traffic rules and possible requirements and orders [?] are obeyed.
Some bike-friendly web sites argue that bike convoys are not excessive road use, but the legal text doesn't give any exemption for them. My (IANAL) legal understanding is that smallish bike convoys (say, a few subgroups of 2 x 5 or 2 x 8 bikes each) are not excessive, but I'd not be surprised if a convoy of 300 bikes would be considered to require such a permit because of the sheer number. Particularly considering that Swiss (and German) culture tends to put a lot of emphasis on organizing/planning everything: a convoy of 300 bikes is not something that I'd expect to happen here accidentally.
Update about Switzerland:
- @bookmanB. pointed me to art. 43 Swiss Verkehrsregelnverordnung (traffic rules regulation).
This article does allow > 10 bikes that are driving in "geschlossenem Verband" (convoi, but see below) to ride in two besides each other instead of single file if this doesn't hinder other traffic. It does not give any other rules for convoi riding, though.
In contrast to the German StVO, I could not find any rules nor privileges for convoys (geschlossene Verbände) in general.
I did find an answer letter by the police to a motor biker asking about convoy driving (Konvoifahrt):
[...] Das Fahren im Konvoi ist in der Schweiz nicht erlaubt. Es gelten die allgemeinen Verkehrsregeln (Rotlicht, Stopp etc.). Es gibt keine Rechtsgrundlage, dass die Verkehrsregeln für Konvois nicht gelten würden. Ausnahmsweise wird für Konvois eine Bewilligung erteilt, sofern ein erhöhtes öffentliches Intresse daran besteht (vgl. Harley Ausfahrt für Krebskranke in Dübendorf). [...]
Es ist auch schon vorgekommen, dass die Kantonspolizei, Organisatoren von Motorradausfahrten beraten hat, wie rechtskonform gefahren werden kann. Dabei empfiehlt die Kantonspolizei Zürich in Gruppen mit weniger als 20 Teilnehmenden zu fahren. [...]
Convoy driving is not allowed in Switzerland. The normal traffic rules apply (red traffic light, stopping, etc.) There is no legal basis on which the usual rules would not apply to convois. In exceptional cases of higher public interest, special permits for convoi driving are granted (e.g. Harley tour for cancer patients in Dübendorf). [...]
The cantonal police has given advise to organizers of motor bike tours on how to drive conforming to the law. In this case, the cantonal police of Zürich recommends going in groups of less than 20 participants. [...]
Thus, no convoy priviledges without special permit (for civil individual traffic, military and civil aid can have special rules).
Passing: Art. 35 SVG (road traffic law)
Im Kolonnenverkehr darf nur überholen, wer die Gewissheit hat, rechtzeitig und ohne Behinderung anderer Fahrzeuge wieder einbiegen zu können.
Wer überholt, muss auf die übrigen Strassenbenützer, namentlich auf jene, die er überholen will, besonders Rücksicht nehmen.
In Kolonnenverkehr [don't know the English expression, it's when the traffic goes in a file, but doesn't belong together as in a convoy], one can only pass if one is sure to be able to get back into the lane in a timely manner and without hindering other vehicles.
Who passes, has to particularly consider other road users - especially those whom they are passing.
Which was violated by the car driver. And of course, passing is only allowed if the necessary space is unambiguously clear.
Dem sich ankündigenden, schneller fahrenden Fahrzeug ist die Strasse zum Überholen freizugeben. Wer überholt wird, darf die Geschwindigkeit nicht erhöhen.
The road is to be cleared for passing for the faster and signaling vehicle. The one who is passed, must not increase their speed.
So maybe honking (in a non-aggressive [!]) manner is just signaling that they want to pass according to art. 35 SVG.
Also, slow motorized traffic is required to leave space in front and even to pull out in order to allow faster traffic to pass (Art 10 VRV), but bikes are not mentioned in this respect. They'd still need to not hinder other road users any more than necessary, though.