The "TruBlue Speed" auto belay device fixed at the top of an indoor climbing route

An auto belay (or autobelay) is a mechanical device used for belaying in indoor climbing walls, in both training and competition climbing formats. The device enables a climber to ascend indoor routes on a top rope but without the need for a human belaying partner. The device, which is permanently mounted in a fixed position at the top of the route, winds up a tape or steel wire to which the ascending climber is attached. When the ascending climber sits back, or falls, the auto belay automatically brakes and smoothly lowers the climber to the ground.[1][2]



Eddy current brake

Breaking methods are electromagnetic, hydraulic, and based on centrifugal force.[3] The electro-magnetic method uses the Eddy current brake principle. It requires a conductive disk that rotates through the magnetic field of a strong permanent magnet. When the disk moves, the magnet exerts a drag force on the metal which opposes its motion, due to circular electric currents called eddy currents induced in the metal by the magnetic field. The breaking force is proportional to the weight of the climber. As the magnet and disk are not in mechanical contact, this system does not wear off from breaking.[1][4]

The hydraulic method employs a closed system filled with oil and pressurized air. The braking effect is created by a valve, limiting the oil flow. The system does not adjust to the weight of the climber and is difficult to maintain[1][4]

The method employing the centrifugal force moves breaking pads against a drum when the system rotates during descent. The tear-and-wear is the highest for this method.[1]


While traditional auto belays use a top roping format with the device hanging from the top of the route, in 2021, a new type of auto belay–the lead auto belay–was developed that used a lead climbing format (i.e. the climber clipped into the quickdraws like a normal lead climb on a sport climbing route), where the device was fixed to the bottom of the route.[5][6]


Climber on a competition speed climbing route with autobelay

The main purpose of auto belay devices is the immediate capture of a falling climber, and the controlled descent of the climber once the route is finished (or after the climber has fallen).[1] While a human belay partner is able to tighten the rope on the climber's demand to allow the climber to take a rest on the route before re-trying a sequence (i.e. hangdogging), the auto belay will not "hold" the climber and will instead begin to lower the climber smoothly as soon as they lose contact with the wall.[1]

In recent years, more advanced devices, such as the Trublue iQ+ Auto Belay, contain a secondary braking system and electronic communication, allowing climbers to remain on the wall after a fall, without immediately lowering ("catch-and-hold" mode). This rest period allows climbers to "project" more difficult routes in a style that is more similar to top roping with a human belay partner.[7]

The climber's rate of ascent must not exceed the speed at which the device takes in the wire or tape, to avoid creating slack. Devices specifically for competition speed climbing[2] are therefore constructed with a very quick take-in time, i.e. 15 m in 3.2–3.5 s, which is faster than the world record.[8][9]


There have been a number of serious, and some fatal, accidents regarding the use of auto belay devices in indoor climbing walls.[10][11][12] Reasons include:


See also


  1. ^ a b c d e f Fitch, Nate; Funderburke, Ron (December 2017). Climbing: From First-Timer to Gym Climber. Falcon Guides. pp. 20–26. ISBN 978-1493027644.
  2. ^ a b DAV Sicherheitsforschung (2022-11-29). "Klettern mit Selbstsicherungsautomaten" (in German). Retrieved 2023-09-13.
  3. ^ Head Rush Technologies. "How Do Auto Belays Work: What's Going on in There?". Retrieved 2023-09-13.
  4. ^ a b Achs, Jordan (2 July 2016). "No Belayer Necessary: Understanding Autobelays". Climbing. Retrieved 2 October 2023.
  5. ^ Miller, Delaney (30 November 2021). "Caught by the Machine: Lead Autobelays to Hit the Market". Climbing. Retrieved 1 October 2023.
  6. ^ Anderson, Sam (2 December 2021). "Arrested by Machines: Europe's Lead Climbing Auto-Belay Targets US Gyms". GearJunkie. Retrieved 1 October 2023.
  7. ^ Head Rush Technologies (2023-01-01). "Trublue iQ+ LT/Trublue iQ+ XL Auto Belay" (PDF). Retrieved 2023-09-14.
  8. ^ Head Rush Technologies. "Trublue Speed Auto Belay". Retrieved 2023-09-14.
  9. ^ Perfect Descent. "Speed Drive Auto Belay". Retrieved 2023-09-14.
  10. ^ Anderson, Sam (22 October 2021). "Fatal Auto-Belay Failure Forces Change at Australian Climbing Gym". GearJunkie. Retrieved 1 October 2023.
  11. ^ Beck-Doss, Austin (17 June 2021). "Climbing Gym Fatality: Fort Collins Woman Dies in 40-Foot Fall". GearJunkie. Retrieved 1 October 2023.
  12. ^ White, Daniella (21 October 2021). "Sydney rock climbing gym says autobelay failure caused death". Sydney Morning Herald. Retrieved 1 October 2023.
  13. ^ Miller, Delaney (21 September 2023). "Gym and Auto Belay Manufacturer to Pay $6M in Settlement for Auto Belay Accident". Climbing. Retrieved 1 October 2023.
  14. ^ "Climber Forgets to Clip In, Breaks Leg in Gym". Gripped Magazine. 19 September 2023. Retrieved 1 October 2023.
  15. ^ Berry, Nathalie (29 November 2019). "When You Forget to Attach to the Autobelay". UKClimbing. Retrieved 1 October 2023.
  16. ^ Perfect Descent, ed. (21 October 2019). "Retraction Notice. Urgent Safety Recall Notice" (PDF). C3 Manufacturing. Retrieved 2 October 2023.
  17. ^ Verband der Kletteranlagenbetreiber Österreichs, ed. (28 April 2023). "Achtung! Sicherheitshinweis Autobelay Perfect Descent nach Herstellerwartung" (in German). Retrieved 2 October 2023.