What is a suicide hub?

[eorta7]

Overheard a guy at the lbs say he was using a suicide hub on his bike?

[nameused]

They were used on old road bikes. Pretty much all the threads on the drive train are the same way. So when you backpedal, it starts to unscrew everything

[DaveM]

It's when you put a track cog onto a hub made for a freewheel. Since there is no lockring, if you back pedal, the cog could unscrew which would mean zero braking power.

There are ways to jerry rig a lockring on a hub like this that are not too bad. But I wouldn't recommend riding a bike set up like this without at least one handbrake regardless. Other than the backpedalling issue, there's nothing inherently dangerous about it.