Help Wanted : Chain Length e160 900e

[brw0513]

Hi all.

I purchased this bike a few months ago and I'm really enjoying it. Mostly just commuting to work to get to know it before heading to my local-ish trails.

Originally, there was some chain noise in the tallest gear, but it is now happening in 10th and even 9th gear. The rear derailleur adjustment settings (to set the overall angle and the high and low travel limiters) seemed a little strange since they appeared to be toward the very end of their available range.

So I started reading Shimano's documentation that is easy enough to find online. I suspect my chain is too long and, in the higher gears, is making contact with itself at times when traveling through the derailleur. It's not the original KMC chain, but a Shimano branded chain.

I think the Fox Float X2 has 50mm of travel based on where the "dust ring" has settled.

As shown in the photos below:

* the shock has been disconnected and the rear axle raised to give 50mm between shock mounting eye and the eye of the suspension linkage.
* the chain is on the largest gear on the cassette.
* the bent wire is fitted in the bore of the link pins to give the shortest possible chain length for this arrangement.

Please confirm the chain is too long and should be cut where shown by the "red line" indication and that this cut link then replaced with the quick disconnect link.

Thanks.

 

[Brent8275]

If you cut your chain where you're suggesting, it will be too short. You need to allow enough to run through the derailleur.

In the photos I've attached, you'll see mine from both largest and smallest cogs.

Also my XT derailleur has a rubber bumper to stop noise (circled in red). Has yours got this?

Maybe check your front chain guide as this may be what is causing the noise? Also ensure your clutch is on. Has the derailleur come loose from the hanger? Or maybe its bent?

 

[steve_sordy]

When you have finally determined what you believe is the correct length for your chain, there is one final check before riding. It is essential to avoid potential serious damage to your bike.

Let enough air out of your shock so that you can fully compress it. If you can do that without the chain going bar taut, then when you do a full compression when out on a ride, you will not be in danger of ripping off the mech.

 

[brw0513]

Thanks gentlemen for the replies. Much appreciated.

I ended up using 116 links (i.e. 115 plus the quick break link) on the new chain. This was the chain length fitted to the bike when I purchased it, as shown in my pics. And it seems to be the length of the original OEM chain. I think the chain could be shorter but there is no real need and, as Steve suggested, that could result in some extreme damage.

When measured with a wear tool, the current chain went beyond the 0.75 indication - so well and truly worn. The outer chain plates were digging into the base of the 11t sprocket and that was likely the source of the noise. Shifting was poor into the top three sprockets.

I will keep a much better eye on things now I've replaced the front chain ring, chain and cassette. Not a cheap exercise.

I'm also going to return the top assist speed back from 30km/h to 25km/h. Commuting at the higher speed is nice but it is very taxing on the battery and probably the driveline as well.

I'm not 100% happy with the Di2 XT Deore shifting performance and suspect my derailleur cage is bent. I might take the bike to a shop for verification.