Derailleur issue

[Flowrider]

Just curious, on my two bikes' derailleurs, both have a "button/knob/lever" that when you push in on one bike or lever it down on the derailleur on the other bike, it stays up or down as you wish.

Does anyone know the purpose of this?

[Painkiller]

(07-29-2025, 11:08 PM)Flowrider Wrote:  Just curious, on my two bikes' derailleurs, both have a "button/knob/lever" that when you push in on one bike or lever it down on the derailleur on the other bike, it stays up or down as you wish.

Does anyone know the purpose of this?

this question may need to be re worded, I am having trouble with what it is you are asking

[Flowrider]

(08-04-2025, 11:20 AM)Painkiller Wrote:  

(07-29-2025, 11:08 PM)Flowrider Wrote:  Just curious, on my two bikes' derailleurs, both have a "button/knob/lever" that when you push in on one bike or lever it down on the derailleur on the other bike, it stays up or down as you wish.

Does anyone know the purpose of this?

this question may need to be re worded, I am having trouble with what it is you are asking

Sorry about the confusion. I wasn't sure until I spoke to a fellow rider. He called it a clutch. Said it had a few uses. When you release it, it's easier to take your wheel off and have it on or off depending on the type of terrain you're riding on.

Thanks for taking the time to reply and yeah...not the easiest thing for me to describe.

[meamoantonio]

its a clutch for Shimano MTB groupsets. You're supposed to turn it on as it keeps the tension on your chain so the chain won't slap too much on the chain stay of your frame during gnarly portions of the trail, honestly I just keep it on all the time for my mountain bike since ill be definitely hitting some trails anyway, but on the off chance that you do want to go ride pavement, cement or asphalt, turning it off makes the shifting a little bit more buttery smooth

[ReapThaWhirlwind]

The purpose of the clutch is to prevent the pulley from being pulled forward. It locks the pulley in place which prevents slack being created in the chain such as when the pulley arm is pulled forwards. This can also help to prevent chain drops and not just chain slaps.