Shimano M7100 chain rust - Thron2 6.9

[russellb]

I got a shock on my new Thron2 6.9 specs say comes with a Shimano CN-M7100 chain.
I clean and lube the chain. Came back after 10 days of being away, did 3-4 short one hour rides on the bike in first 5-6 days then no riding. Bike is 100% always covered when outdoors on a trip or on back of van. Given I did not clean the bike while away, but did so little riding and in good dry weather.
The chain looked like the pic attached Bike is brand new, few months old. I have never seen a chain do this.
gave it a good clean, still has a very slight dark tint on the chain.

 

[Bndit]

Since the bike is new, contact shop. I have never seen anything like that. Must be some error on coating if it`s only those outer plates…if you are using normal bike cleaning chemicals. I use same chains.

 

[russellb]

Since the bike is new, contact shop. I have never seen anything like that. Must be some error on coating if it`s only those outer plates…if you are using normal bike cleaning chemicals. I use same chains.

Makes me think with all the bike supply chain issues, if there is some sort of part substitution and or inferior materials being used.

 

[Bndit]

What do you use for cleaning the chain and lubing it?

 

[russellb]

What do you use for cleaning the chain and lubing it?

Just a Muc-off wash/cleaner to de grease, wash off and a Muc-off wet lube and then wipe down the chain of excess lube.

 

[steve_sordy]

I am unfamiliar with the Shimano CN-M7100 chain. I know that chains at the budget end of the spectrum will rust if left after a damp ride or after washing without drying. The higher spec chains can be put away wet and still be OK.

 

[PennywiseTheDancingClown]

I am unfamiliar with the Shimano CN-M7100 chain. I know that chains at the budget end of the spectrum will rust if left after a damp ride or after washing without drying. The higher spec chains can be put away wet and still be OK.

Pretty sure the 7100 is an XT level chain, so definitely shouldn't be doing this.

 

[russellb]

Pretty sure the 7100 is an XT level chain, so definitely shouldn't be doing this.

yup its an XT chain and to do that after a few days is crazy. Def something going on

 

[Bndit]

It's SLX....

 

[irie]

It's SLX....

Even so, it still should not be doing that. Something nasty at work there...

 

[SteveTTT]

Pretty sure it’s a QC issue. I had this with my 2022 Trek Powerfly 7 (purchased October 2021). Same M7100 chain and it went from shiny to rusty almost overnight, despite what I thought was an adequate maintenance regime reflecting typically wet and muddy UK winter riding conditions. Like yours it seemed mainly on the outer plates.

I removed the chain and scrubbed it with WD40 using a brass wire brush. I got the rust off but there was lots of scarring left. It also wore to 0.75% within 600 miles and cost me a new cassette too.

I sold the Trek this April to upgrade to a full suspension emtb. I’m using the same maintenance regime on my Giant Trance Advanced E+ 2 with no rust issues. I think that has a KMC chain and now approaching 0.5% at close to 1000 miles.

 

[Wak]

Wherever you rode last time they had salted the road as there is spots of salt and corrosion on the chain wheel ect you needed to wash ot off and lube the chain properly I boil mine in chain wax no problems and last twice as long

 

[russellb]

Wherever you rode last time they had salted the road as there is spots of salt and corrosion on the chain wheel ect you needed to wash ot off and lube the chain properly I boil mine in chain wax no problems and last twice as long

No that's not it, I'm on the east coast of AU no road salting.

I did ride the bike past a few sand dunes by the beach, no riding in the sand as such, and no water or getting bike wet by sea water etc. I wheeled the bike down a few beach entry paths (sand) to get a few photos.
I did the exact same trip with another bike, same riding, same sealed bike paths, by and on a bit of sand by beach as you go past beach entry paths etc, with no washing bike until I got home, same chain on the other bike, and zero problems and certainly no corrosion.

Keep in mind I cleaned and lubed the bike at start of the 10 day trip which was not a riding trip but took the bike for a few light rides. first 2-3 days was just driving no riding. 3 days riding literally 1 hour each morning along bike sealed paths with a few beach entry paths so you take bike over a bit of sand, dry no water.

2-3 days return to get home with no riding and chain looked like the pic, massive rust build up.
If I had a cheap chain with no corrosion surface treatment etc maybe ? but a high spec chain with corrosion protection, to look like that after 10 days with only a total of 3-4 hours riding while I was away which was mostly sealed bike paths. No wet riding at all.

Maybe thats how high spec chains behave ? I'm not an experienced rider. But I have never seen a chain go like that within a few days.