It’s safe on all surfaces, and it’s even disc brake rotor and pad friendly.
Says Mr Muc Off
Muc off is fine, yeah.
The stuff it dislodges from other bits on your bike might not be fine. Maybe that's what happened to Turkish.
Never had a problem with this myself but the bike shop I used to work in were adamant that muc-off was kept away from disk rotors/pads and rims with rim brakes. They might have just been overly cautious, as I think they only used isopropyl for discs
@Howard started
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Says Mr Muc Off