New chain skips under torque

[chriswoody]

All I know is this
https://mtbdatabase.com/bikes/2022/yt/izzo/2022-yt-izzo-core-3/
but I can get pics of the bike. Mostly GX EAGLE.

The limit screws are no problem. Never moved. Just checked them this evening. In the bench clamp, it runs perfectly.

The main mystery right now is why the new XX1 chain is skipping so badly, on the bottom 3 gears at least. But with the bike in the clamp it all runs fine. I've put the old chain back.

So like my bike your bike is running a GX Eagle Cassette, derailleur and chain.

As you say, your symptoms mimic the those experienced in this thread and suggest that the cassette and chain are both worn and need replacing. If that's the case, as I mentioned, I have had nothing but positive experiences with SRAM's bottom of the range 12 speed GX Eagle Cassette. In the UK as far as I can tell, this cassette would cost about 150 pounds and a NX Eagle chain would cost about 15 pounds. Not cheap, but then much better than 500 pounds.

Have you got a good chain checker tool? keep an eye on the chain, replace it early and you can should get through at least 3 of them before you need a new cassette. NX Eagle chains are perfectly fine for this drivetrain and relatively cheap. Also keep the drivetrain clean, it doesn't need to be excessive, like I said I just keep the outside of the chain clean by wiping it with an oily rag.

 

[peter-h]

Thank you - I will do that as the next move.

Can the XX1 chain (£80) be used? I already have it. After all, SRAM say all 12-speed stuff is mutually compatible

I don't have a chain checker but I can hold an accurate steel rule next to it. The current one is exactly 1/16" extra, across 12". Somehow, the casette got severely worn. It was a £150 one, 1 year ago.

 

[mickle]

Thank you - I will do that as the next move.

Can the XX1 chain (£80) be used? I already have it. After all, SRAM say all 12-speed stuff is mutually compatible

I don't have a chain checker but I can hold an accurate steel rule next to it. The current one is exactly 1/16" extra, across 12". Somehow, the casette got severely worn. It was a £150 one, 1 year ago.

Thank you for reminding me why i stuck with nine speed. A top qual plated 9 spd chain can be found for less than a tenner.

 

[silva]

A sprocket worn by the increasing pitch of the wearing chain, faces a number of simultaneous engaging rollers, thereby that number of teeth "helping" eachother = dividing the load, and, they wear towards that simultaneous engaging, because if less engage, those that engage will wear, and those that don't, not, bringing the wear states towards the same.

In contrast, a new chain on a worn sprocket, just one roller will engage a tooth, the other teeth don't contact due to material worn off, thereby the load being on just that single tooth, and it will only arrive at aboves situation when the new chain arrived at the pitch of the old one.

So, a load, that didn't cause skipping with old chain, does cause skipping with new chain.

 

[peter-h]

That's a great explanation.

But surely there must be another factor, because this issue was unknown for all the 200 years (?) that bikes have been around There is something about these products which relies on a super tight tolerance. Possibly even just 10-12 speed systems?

Look at the weird tooth shapes we now get. Every x teeth is a funny shape one, and all the teeth are a different (sort of tapered, when viewed in the plane of the gear) shape to what they always were. Supposedly to deliver easy shifting under increasing torque (when initially going up a hill).

 

[chriswoody]

Can the XX1 chain (£80) be used? I already have it. After all, SRAM say all 12-speed stuff is mutually compatible

Should be absolutely fine.

Just one thing that has occured to me, check the quick link on your new chain. They have a small direction arrow on them and if you fit them the wrong way round it will cause issues.

 

[peter-h]

I also wonder whether I should change to a 10 speed. I use only 8 of the gears. The last two are so slow they are, I find, not usable, because you are pedalling like crazy, perhaps up some 45 degree slope, and I cannot keep my balance
But that means also changing the selector and the derailleur, no? Certainly the selector because that is where the pitch is determined.

 

[Ajax Bay]

Pasting the post (edited) in the other forum as there's detail there.
"I have a YT bike, Izzo CORE 3 Black Magic M, year 2022.
https://mtbdatabase.com/bikes/2022/y...t-izzo-core-3/
"[Ride 3 hours a week] Nearly 70 so nothing too crazy

"A year ago I changed the chain. Immediately . . it was skipping on the smallest gear. [Comment: think smallest sprocket.] rear casette replaced ££. [Rode] fine.
"[Now] chain [suck]. (SRAM 32T EAGLE XSYNC 2). I guessed the chain is worn, so I got a new SRAM XX1 EAGLE 12-speed chain, £81. Immediately found it skipping not just the bottom gear [Comment: Likely means 'top'] but also the next two.
"Gearchange was not working as before and needed adjustment (why??) but I could not get it right. Put the old chain back. I ordered a new front gear; they are cheap £15 (are these counterfeit??). SRAM X-Sync 2 Steel Direct Mount Boost Chainring 32T. SKU: SRMCW8041004."

Adding here the comment on the other forum's thread, in the spirit of @mickle :
"i'm still trying to wrap my head around a 69 yr. old buying a wild eyed $4500 CF MTB with mondo travel and big brakes.... for leisurely exercise rides...

but hey... if you're happy... "

From all this I'm deducing that @peter-h with a 1x 32t chainring spends most of his time on the 10t and 11t sprockets (when not climbing "45o hills") and that's why those sprockets are skipping with a new chain on. Also 3 hours' riding a week for a year is (say) 1500 miles - quite likely the chain has elongated, wearing the cassette, hence the skipping.
On 'should I go for 10sp'? The rear hub is DT Swiss M1900 Spline wheelset, 148x12mm Boost rear with XD driver
I suspect you cannot get a 10sp cassette which fits that, and yes, that'd mean changing the front brake/shifter for a 10sp one (NB hydraulic).
My recommended way ahead: N-1 for the most you can get and then N+1 for a nice 11sp 1x gravel bike weighing 4kg less *without front or rear sus obv for "~3hrs of tarmac+track each week". You're welcome.