Critical Mass


Critical Mass Brno was re-founded in May 2017 and takes place every first Wednesday every month at 19.00. This event is organized by a citizens' initiative Brněnská Cykloguerilla (Bike Guerilla Brno).

Some people call Critical Mass in Brno "Zkouška sirén" (Siren test) after siren tests which are held in the Czech Republic every first Wednesday at noon.

Meeting point: Moravské náměstí / Moravian square, google maps



Facebook Group:

Facebook Page:

Bicycle rides are documented by local photographer Jakub Kris. Photos are available at his Flickr photostream -

Former bicycle rides[]

Other bicycle rides have been happening in Brno, however they are different than Critical Mass rides due to their official status.

Most notable were Nakoleon bicycle rides. First Nakoleon mass ride took place on 19th September 2013 and was attended by 1050 people. Second Nakoleona mass ride took place on 20th September 2014 and was attended by 1400 people. Another significant bicycle ride was Great Spring Bicycle Ride on 16th April 2015 attended by 1000+ riders. Those rides were official events organized by local cycling advocacy group Brno na kole (Brno by bicycle) in cooperation with police department and commercial partners.

2024 reflection and plenary[]

After seven years of monthly rides, the first organized group reflection and discussion about Critical Mass in Brno took place in the form of a plenary session on 19th June 2024. The following topics were addressed:

  • The goals of the bike ride, why we actually do it
  • Fixing the departure time, as there have been delays of up to an hour in recent years
  • Aggressiveness of participants and creating a safe space
  • Excessive alcohol consumption
  • How to create conditions for participants to get involved in preparation and organization
  • Corking and rules

The conclusion of the plenary session was that we want to improve the bike rides, fix issues, and make them a safe space again. To achieve this, we need more people; we know what else we want to do, but now we must engage more individuals to make some changes happen.

Following the plenary session, a directory was established at, where the minutes of the plenary session (in Czech) are also available.

Past CM rides[]

2017 October[]

Around 50 people gathered for CM on 4th October 2017. Critical Mass rode to a north of the city through Technical University student's campus. Route length was 17 km.

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2017 October

2017 November[]

There were app. 25 riders attending this month. The ride went north again around Lesna neighborhood, total distance of 15 km.

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2017 November

2017 December[]

December ride featured St. Nicholas theme reflecting Czech traditional custom - riders dressed as Angels, Devils and Nicholases. App. 40 people attended the ride 11 kilometers long.

CM 2017 12 06

2017 December

2018 January[]

Freezing weather have welcomed 45 riders. The meeting point was moved in front of Supreme Administrative Court at Moravian Square due to temporary ice-ring built in traditional meeting point. The route led riders through some icy road which caused several falls, however there were no injuries. At Nadrazni street a Regio Jet coach driver has driven against critical mass. The same reckless and dangerous driving took place couple of months before. Total length of ride was 13.4 kilometers.

CM 2018 01 03

2018 January

2018 February[]

Some 25 participants took ride in February. The length of a route was less then 9 kilometers. During the ride two stops were made during which information about upcoming street reconstruction (Plotni and Dornych streets) or infrastructure project (Hladikova underpass at Svitava river) were shared.

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2018 February

2018 March[]

Women's Strike Critical Mass, app. 30 people rode 7 km.

CM route 2018 03

2018 March

2018 April[]

20 people (?) attended, the route had app. 12 km.

CM route 2018 04

2018 April

2018 May - Birthday Critical Mass[]

Surprise, surprise! Almost 100 hundred people rode and celebrated 1st birthday of Critical Mass Brno! There were some birthday cupcakes for participants. A capitalism suffered a fatal blow when Critical Mass rode through a mall's garages. The length of the ride was app. 17 km.

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2018 May

2018 June[]

Some 70 people rode on 6th June 2018. Weather was warm and nice, people were having pleasant summertime. Ride stopped by Svratka river to have a quick swim and then to ride again. Two soundsystems were playing music, one from the behind and the other one in ride's front. The ride finished back at Moravian Square where several people stayed partying around soundsystem playing psytrance beats until it was past midnight and local police asked to turn the music off. Good ride, good life, good people. Ride was 18 km long.

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2018 June

2018 July[]

Nice ride, up to 100 people arrived, there was again swimming intermezzo, the ride ended after almost 20 km at Na draze Club.

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2018 July

2018 August[]

It was hot summer evening and it was decided before (in facebook group) to ride south and swim. 50 to 70 people joined the ride and rode south according to pre-agreed route. Finally we have explored south of Brno, including the roads which were unknown to many participants. The ride ended traditionally at Moravian square after 22 kilometers.

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2018 September[]

This ride was dedicated to Lukáš who was struck by drugged pizza delivery driver two weeks before. Lukáš suffered serious injuries and during the ride still remained in critical conditition fighting for his life. Almost two hundred people came and rode. For the first time, the police followed the ride, probably to secure that no blocking of motorized traffic is going to happen. The route distance was app. 14 km.

Cm 09

2018 September