Is it possible that the lumen is not stated correctly (in your case 50lm)? Please compare it with the BBB website and correct it if necessary:
https://bbbcycling.com/ch_de/bls-137-signal

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Answer

Correctly indicated. 50 lm in Day Flash mode

Answer

We were happy to check this and the page you linked also states a max. lumen of 50 lm. However, this is only in flash mode. In continuous mode, it would only be max. 20 lm.

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Question about BBB Signal

Is it possible that the lumen is not stated correctly (in your case 50lm)? Please compare it with the BBB website and correct it if necessary: https://bbbcycling.com/ch_de/bls-137-signal