Just picked up the boys new bike, I thought “What’s that ?” It looks like a bed-spring going from the back of the rear mech, along the length of the arm and hooked into the end of the arm by the bottom.

It’s a 9 speed Deore that’s fitted to a Giant/Liv 2017 model… I can’t see it on any of the pics on various websites so i assume it’s a ‘home made’ tensioner system like a clutch mech sort of thing ? LOL

I remember something similar from about 20 years ago when I used to read MBUK regularly. A bit like a DCD it was the in thing to be seen with for a while.

Quick bit of Googling and I’ve even found the name and one for sale in the classifieds…

Probably a Bullet Bros Chain Tensioner. I had one in the day:

Yup, I had one too. I never understood what the little notch in the top was for…

Same logic but wasn’t attached to an arm like that, was just attached to the top of the mech near the QR.

It’s removed now, but it was certainly a thing i found interesting. Especially as it made shifting really hard !

Was it just used for keeping the derailleur safe when in transit much like bolts on a washing machine?

I had a bullet bros tensioner on my recumbent. Brilliant for helping keep that long heavy chain in check.