Sram Eagle GX chain and cassette issue?

[baydoh]

I just had my Trek Rail have it's 1st service after 700km. The shop called and said i should replace my chain as it probably wouldn't make the next service, i was happy to replace it. Chain above 0.5
Shop advised that a new chain doesn't mesh well with the original cassette ( slipping under load in a few gears ) they don't have a cassette in stock at the moment.
They put the original chain back on and have given me two options.

1 Ride the original chain / cassette into the ground and replace both.

2 When a new cassette comes in i could purchase that and a new chain.

I'm confused as to why a new chain doesn't "take" to my original cassette after 700 km is this normal? Or is the cassette faulty and this could be a warranty issue?
What's the point of buying a new cassette now as this appears to be fine.
I have cleaned and lubed this after every ride and regularly use a chain cleaner to attempt to extend the life out of the drivetrain. I'm happy to burn through a new chain every 1000km if this means i don't have to replace cassette etc. Cheers

 

[Paul Mac]

Unfortunately this is normal wear on an ebike.
I have the same bike as you and had exactly the same issues.
Just run the same chain until it starts not changing gear properly, You'll get another 1000 k out of it, then renew the whole lot.

 

[GMLS]

I think I've got exactly the same problem as you Changed by original SX chain on my Cube for a GX chain (cassette fine) and I'm having a hell of a problem stopping it slipping in the smaller gears I was told all SRAM parts compatible.

 

[steve_sordy]

The bike shop did well to test and advise you that the new chain will not run well under load with the good cassette. Normally the test is done on the bike stand alone, where it would run OK. Also, they haven't charged you for the new chain either.

The cassette has worn to the point where it will no longer run well with a new chain, but will still run with the old chain because they have worn into each other. Not a very technical description, but that is the effect of it.

What I have done in the past is to refit the old chain until I can get a new cassette delivered. Then fit the new chain and cassette. If you keep running the old chain, you will wear out the front ring too. Nothing transmits wear faster to gears than a worn chain. Or just run the whole lot until it will no longer function acceptably and then replace the lot.

 

[steve_sordy]

I think I've got exactly the same problem as you Changed by original SX chain on my Cube for a GX chain (cassette fine) and I'm having a hell of a problem stopping it slipping in the smaller gears I was told all SRAM parts compatible.

They are compatible. The problem is as the OP and respondents have outlined.

 

[Hob Nob]

Seems weird, the GX cassette is all steel, you have to be really going some to wear it out that quickly - have you been riding in wet sand for all it’s life?

I have an X01 cassette on mine which is essentially the same steel, just a lighter construction, that cassette had done over 7000km on a normal bike & would still take a new chain. It’s now been on my eeb since July & done about 2500km - just put a new chain on it & it shifts fine.

 

[GMLS]

Seems weird, the GX cassette is all steel, you have to be really going some to wear it out that quickly - have you been riding in wet sand for all it’s life?

I have an X01 cassette on mine which is essentially the same steel, just a lighter construction, that cassette had done over 7000km on a normal bike & would still take a new chain. It’s now been on my eeb since July & done about 2500km - just put a new chain on it & it shifts fine.

I've done 500 miles on it over the last 5 months and cleaned after every ride which is why I don't think the cassette is worn but as suggested above perhaps it is. i'm going to completely readjust the derailleur from scratch and go from there.

 

[Mikerb]

The smallest cogs have the least chain wrap and wear the quickest especially if those are the gears most used. I think changing a chain at 0.5 is not sensible on an ebike, especially if used in sandy/wet/muddy terrain. I found that chains quite quickly wear to 0.5 but continue to work fine and wear less quickly after that. A casssette is usually good for 2 chains worn up to .75. After that it is a new chain and cassette. On my Levo 2 chains/1 cassette lasted for 1200 miles and the second chain was still working well.........a 3rd chain on the original cassette would slip occasionally in the highest 3/4 gears so new cassette also then required.

 

[baydoh]

It seems very costly just to run a chain until its unusable then purchase a new cassette, chain and chain ring everytime.
I will run this set-up then purchase the lott.
Should i replace a chain every 500km to avoid this happening again. E-bikes seem to be like owning a boat hahah

 

[Rahr85]

My gx Eagle xg-1275 has done 1361km and is on its second chain. Its now too worn to get away with another but its not skipping gears yet.

I'm going to downgrade to a shimano freehub and eventually go 1x10 deore as I can forsee myself doing a lot of miles and don't really need the full range that this offers.

 

[Paul Mac]

It seems very costly just to run a chain until its unusable then purchase a new cassette, chain and chain ring everytime.
I will run this set-up then purchase the lott.
Should i replace a chain every 500km to avoid this happening again. E-bikes seem to be like owning a boat hahah

You have to run ebike transmissions differently to regular bikes.
If you tried to change your chain every time it gets to 0.5 wear, you will be changing your chain about every 4 rides, plus it will still slip when you get to your 3rd chain.
At present I'm trying a two chain approach, I'm rotating them every 200 miles.
Got 1000 miles so far and both chains are now just over 0.5 wear.

 

[Mikerb]

Here's a thought.....and it is just a thought! I wonder if a cassette would last a little longer without chain slip if the chain was always oriented with the cogs on the same part of the chain...ie either the wide chain link or the narrow chain link? Given that cassettes are not narrow/wide, the cogs on which the narrow links run must wear more than those running in the wide chain links? So assuming a chain has been running on the cassette for an extended period of time without the rear wheel being removed the parts running in the narrow chain links would wear more?

 

[Rosemount]

Here's a thought.....and it is just a thought! I wonder if a cassette would last a little longer without chain slip if the chain was always oriented with the cogs on the same part of the chain...ie either the wide chain link or the narrow chain link? Given that cassettes are not narrow/wide, the cogs on which the narrow links run must wear more than those running in the wide chain links? So assuming a chain has been running on the cassette for an extended period of time without the rear wheel being removed the parts running in the narrow chain links would wear more?

I think there is enough randomness in the chain / derailleur / cassette .
The chain won`t derail and climb in the exact same spot every time . There is a human factor as well .

 

[Mikerb]

I think there is enough randomness in the chain / derailleur / cassette .
The chain won`t derail and climb in the exact same spot every time . There is a human factor as well .

...but because the chain ring is narrow wide, the chain stays in the same place in relation to the cassette until/unless you remove the rear wheel or chain?

 

[Rosemount]

Dang Mike all this thinkin is starting to hurt ! lol .

The chain ring yes .
The rear end can have many combinations I think .
eg when my chain needs lube it can take more rotation of the cranks before the gear will change .Does it still change in the same spot but one rotation on ? Don`t actually know .

 

[Gary]

 

[Rosemount]

Hey Gary !
Up before the sun , and trolling already . I admire your dedication .
4:00 AM
Monday
February 1, 2021

 

[steve_sordy]

...but because the chain ring is narrow wide, the chain stays in the same place in relation to the cassette until/unless you remove the rear wheel or chain?

It will stay in the same place on the ring and the jockey wheels, but not the cassette. You initiate shifts at random intervals from one gear to another, sometimes more than one at a time where the shifting permits. The numbers of teeth on each gear are irregular as well, only 4 out of 11 are even numbered, the other 7 don't even divide evenly by two. Some are even prime numbers (5 on my 11-speed), so I'm as sure as I can be that any particular tooth on a cassette gets an even wear from the narrow part of the chain as the wide part. If it was predictable, the cassette gears would all be narrow/wide. The above is why they are not.

 

[GMLS]

Having done more research, it sounds like the GX is very sensitive to the position of the B gap
so I'm going to focus on getting this right as everything else seems fine. I don't have the red gap tool he has to assist though

 

[Kernow]

He’s right that b gap is very sensitive on sram , and to set to set it while sat on the bike .
There’s no way there should be much wear on the cassette after the first chain is worn to 0.5 .unless something has been way out , but then you would have noticed bad shifting already
Be sure you’ve got the right 12 speed chain not an 11 speed .
The jockey wheel screws and mounting bolts can tend to come loos on those mechs so check that .
As in that vid the mech if the mech has had a knock , it doesn’t take much to put the hanger out of line , and I find lots need re setting from new
Any problems getting shifting right and this is often the problem , an alignment tool is a useful thing to have and cheap enough . In fact there’s a vid on how to make one below this . It’s the starting point , along with that b gap

 

[steve_sordy]

My gx Eagle xg-1275 has done 1361km and is on its second chain. Its now too worn to get away with another but its not skipping gears yet.

I'm going to downgrade to a shimano freehub and eventually go 1x10 deore as I can forsee myself doing a lot of miles and don't really need the full range that this offers.

View attachment 51733

That cassette does not look badly worn to me. I have seen much worse that still operate. Yes it is scuffed and the finish is worn, but the tooth shape looks OK. The smaller gears look the worst.

 

[Rosemount]

Having done more research, it sounds like the GX is very sensitive to the position of the B gap
so I'm going to focus on getting this right as everything else seems fine. I don't have the red gap tool he has to assist though

That guy in your vid has excellent content .
I watch his channel regularly . Mix and match series even mix SRAM and Shimano !

 

[Kernow]

That guy in your vid has excellent content .
I watch his channel regularly . Mix and match series even mix SRAM and Shimano !

I notice he’s also running an oval front ring , that’s going to mess with his b gap setting I guess I love ovals but not tried them with sram , they certainly don’t cause any problem with shimano . Irrelavent to ebike anyway

 

[Rosemount]

I notice he’s also running an oval front ring , that’s going to mess with his b gap setting I guess I love ovals but not tried them with sram , they certainly don’t cause any problem with shimano . Irrelavent to ebike anyway

He added a detail from SRAM re oval chain rings .
Crank at 1 o clock normally .For oval crank at 4 o clock That guy knows drive trains . I have watched at least a dozen of his vids comparing brands and series .

LOVE MTB channel

 

[Konanige]

I notice he’s also running an oval front ring , that’s going to mess with his b gap setting I guess I love ovals but not tried them with sram , they certainly don’t cause any problem with shimano . Irrelavent to ebike anyway

Have run oval rings on clockwork bikes for last 6 years due to dodgy knees, they are great and have absolutely no effect on your B screw setting.

 

[Konanige]

Here's a thought.....and it is just a thought! I wonder if a cassette would last a little longer without chain slip if the chain was always oriented with the cogs on the same part of the chain...ie either the wide chain link or the narrow chain link? Given that cassettes are not narrow/wide, the cogs on which the narrow links run must wear more than those running in the wide chain links? So assuming a chain has been running on the cassette for an extended period of time without the rear wheel being removed the parts running in the narrow chain links would wear more?

The chain wear occurs on the rollers of the chain and not the outer plates so whether its running on a narrow section or wide section makes no difference, and there are too many combinations to do it even if you wanted to.

 

[Shjay]

Having the red sram tool for setting up 12speed Eagle is a far more important tool than a mech hanger alignment tool, without it you will struggle for a long time to set up gears!!

 

[Gary]

No it's not.
Infact the plastic guide tools aren't even needed if you know what you're doing.
wheras with an out of alignment mech hanger you're never going to get 12 speed Eagle to shift well acrossthe whole cassette.

 

[Shjay]

Well I use both as I do it for a living & have no issues with either thanks Gary but am sure your a mechanic by trade too!

 

[Gary]

Then you should also know that chain length and chain growth both affect where the top jockey wheel sits in each gear.
and using those plastic guides to determine B-tension adjustment does NOT actually give the top jockey optimum position throughout the full range of gears on all bikes. not to mention the fact that there's no standard placement for a rear mech hanger throughout the industry so not all mechs sit in the same position relative to the rear axle.
They're good enough as a guide for a beginner or home mechanic though

I'm really surprised you dismissed the importance of gear hanger alignment on a 12 speed system. Have you been a shop mechanic by trade long?