Clutch mech adjustment

thistle_

I have an SLX 11 speed mech with a clutch in a 1x11 setup.
I noticed yesterday while riding that pedalling seemed hard at times but thought I was just unfit.
Today I was cleaning/fettling and noticed that it was tough turning the cranks by hand, however when I flipped the lever to turn the clutch off the cranks went light. Clutch back on and everything was fine until I shifted gear, clutch off made it ok.

Do I just need to take some tension off the clutch or is there something else wrong?

steve_sordy

The clutch should make no difference to your cranks at all. All the clutch does is to impose some rotational friction on the mech arm to stop the chain from flapping up and down. So if is doing something else, I'm not sure what. The worst it has done for me is to make shifting slightly harder because it requires slightly more pressure on the big lever.

The clutch release lever is there to make wheel removal easier. If it makes a difference to pedalling (and I can't see how) then leave it off for a while and see what happens. Something will develop.

thistle_

Well I slackened off the clutch slightly, and pedalling is a lot easier, although the chain dropped more frequently as you might expect.
I'm wondering whether the chain is too short (before adjusting the clutch) the chain was very tight after shifting). More fettling to add to the list.

steve_sordy

thistle (MBNW) wrote:

.............
I'm wondering whether the chain is too short (before adjusting the clutch) the chain was very tight after shifting). More fettling to add to the list.

Put your chain in the biggest front gear and the biggest rear gear. Have a look at where the mech arm is pointing. It should be no more than pointing forward at 45 deg to the horizontal. If you ride a full suss, then even that may be too far forward. If you have a single pivot or a faux bar then you'll be OK, anything else and you will need to compress the rear to be certain that the chain is not too short. To be sure, either let all the air out of the shock, or get a very heavy friend to fully compress the coil shock.

The Rookie

Sorry that’s simply not true, in the biggest gears on a hardtail or FS with no chain growth it should be all but horizontal, big big plus two links. Otherwise you risk not having enough capacity to keep it taught.

steve_sordy

The Rookie wrote:

Sorry that’s simply not true, in the biggest gears on a hardtail or FS with no chain growth it should be all but horizontal, big big plus two links. Otherwise you risk not having enough capacity to keep it taught.

I agree that my method is different to yours, but it does not make it "not true". See below for a wide variety of methods, all of which are different, but "true". Sram and Shimano know what they are talking about I reckon. However, bikes are so different as are the demands and expectations of the riders, such that experimentation takes place. Here is a summary of are a few methods of setting your chain length. It does not ignore those full sussers that do have chain growth.

Setting Chain Length – a variety of methods

In the various sources consulted, there is some ambiguity over what is meant by a link. Is it one link of ½” or two links, one inner and one outer (ie a complete link) of 1”? It has to be two half inch links, because otherwise the chain ends won’t connect.

Hardtail or Full Suss?
All the techniques below work for all bikes, but there is an extra step for full suss bikes: Ensure the shock is fully compressed when you do this (let the air out if you are on your own) to ensure the chain growth in the suspension system doesn't interfere with the drivetrain. Depending upon the suspension design, this step could prevent severe damage to your rear mech.

Shimano Method
Run the chain over the largest ring and over the smallest sprocket on the cassette and through the derailleur as normal. Adjust the chain length so that the derailleur hangs vertically.

SRAM Method
Run the chain over the largest ring and the largest sprocket, avoiding the derailleur. Add one link. This sounds very tight, but not tried it.

Add six links
Run the chain over the big to big, avoiding the derailleur and then add six chain links (3” in this case). I must say, that although I have used it, I never felt happy with it. Bike shops seem to use it because that is what I get when I checked a new bike. On my Kona Dawg, this gave a slack chain with lots of slap on the chainstay.

Big to Big
Leave the chain running through the derailleur, go big to big and shorten the chain until the derailleur is pointing forwards at 45 degrees.

Small to Small
Go small to small and set the chain length where it sits close to the chain coming around the top jockey wheel. Adjust so that the two chain paths just clear each other. It's generally 1 link shorter than the Shimano method, but it runs quietly and works for everything other than bikes with massive chain growth through the suspension.

Kevolution’s method (basically - small to small, with the FS check)
“I set my chain length by setting the gears in granny ring and smallest sprocket then removing links until the chain doesn't contact the upper jockey wheel of the rear mech. This is generally one link shorter than the Shimano preferred method, I find it allows for quieter running and better shifting.

If you use this method on a double & bash setup with a short cage mech, set the gear to middle ring and larger sprocket, deflate the shock and compress it fully to ensure the chain growth in the suspension system doesn't interfere with the drive train.”


PS: Kevolution was an ex DH team mechanic and now bike shop owner somewhere in S Wales. Not heard from him for years.

The Rookie

The variety of methods all end up at pretty much the same length, which is simplified to big big plus one pair.

If the mech isn’t pulled forward as per manufacturers instructions you lose capacity obviously.

steve_sordy

I suspect that all these rules are designed to simplify the life of the people assembling new bikes. Something that is safe, works every time and yet doesn't give any problems down the line. But bikes are different, riders have different experience and ride in different places. It is good to know what is trying to be achieved. And that is a chain that shifts well, and is as short as possible without risk of damaging the mech in a full compression.

I have seen riders with chains that are so slack that they must have bought a new chain and just fitted it without bothering to adjust the length. I helped a guy once with a snapped chain. I could see straight away that it was too long and I removed 4" of chain. I even connected his chain with a spare magic link. The reason I remember all this is that afterwards, he just rode off without even saying thanks. I was the stupid bugger left with oily hands and an astonished look on my face. Despite that, I still help other riders, but now I get them to do more of the work!