[Closed] Clutched rear mechs. Do you......?

I leave mine switched on all the time..

Only switch mine off when removing the wheel

It's a band clutch so not likely to relax

They are adjustable though

You only release it to remove the rear wheel.

Yeah leave on all the time..... Its not really a spring.... Its just a cam that tensions a bit of bent metal around a central pin which the swing arm of cage is fixed to.... The cam acts on the bent bit of metal to tighten.... Like a strap.

Here is a pic of mine.... I found that the tension was a little weak on mine out the box so I needed to tighten the preload screw.

[IMG] [/IMG]

I thought the SRAM ones unlocked themselves after a bit if you ride off with them locked?

How do you tighten a sram one then?

The SRAM clutch mechs dont work the same. The lock on a SRAM much is just a pin that holds the cage forward, so you can remove the wheel. If you left it locked you wouldn't be able to pedal, as the chain would be too slack.

The clutch is always engaged, its just a roller bearing, which out of the box is dry. So of you have a suspension bike that relies on chain growth, you need to pull it apart and add pivot grease or the much will constantly clunk when you pedal.

You tighten the SRAM by increasing the preload on the roller bearing, its under a little cap, and is a t50 torx bolt, you just tighten it and this pushes a tapered bearing further against the roller bearings, increasing contact and torque, which in turn increasing friction and stiffens it up.

I don't think you do (though I'm willing to be corrected) - unlike Shimano ones, where the clutch is active to keep the cage to the rear, IIRC SRAM use a much simpler clutch to hold the cage forward when locked, and a beefy spring to increase chain tension when unlocked.

Cheers rick, been suffering with quite a bit of chain droppage recently so that may help reduce

If you do take it apart, be bloody careful. Look in my history for a post I wrote about how to take it apart, as you could end up with a broken mech.

If you're just tightening it, the small button is all you need to remove, just the inside bit, use a Stanley knife to pry is off. That'll reveal the t50.

What is it the clutch does, and if it's so good, why have the option to turn it off?

[quote=aphex_2k ]What is it the clutch does, and if it's so good, why have the option to turn it off?

It stop the mech flapping round, so reduces chain slap. In effect it makes the mech much harder to move. The off switch is so that you can loosen off the tension to get the wheel in and out. The SRAM version just has a push in pin to lock the mech out of the way.

Does work pretty well.... Not as good as dedicated chain tensioner but for light xc/trail use, it does stop most chain drops and reduces slapping. I run two of these, one on each bike.... One was nice and stiff out of the box the other was weak so needed adjusting.

They do make shifts much stiffer though! That's the only downside I would say. You need to make sure you have nice clean free running cables!

Tried it for the first time today and I'm very impressed. Thanks for the pics of the inside workings. Now I understand how it works.