I have a YT bike, Izzo CORE 3 Black Magic M, year 2022. Nice bike, rides well on tracks with stones on them.
I ride 1hr, 3x a week, for fun and fitness, part tarmac, part tracks. Nearly 70 so nothing too crazy Reasonably mechanically minded, have a workshop with a turret mill and a lathe. But not familiar with "modern" bikes and special tools required.

A year ago I changed the chain. Can't remember why. Same type AFAIK. Immediately found it was skipping on the smallest gear. Well, yeah, old chain has a longer pitch. I gave it to a local bike service guy; he said the rear casette needs replacing to match. Kind of made sense. Few hundred quid! I got all that done and it was fine.

Last few weeks, I am finding the chain is behaving funny. I discovered that it is not "peeling" properly off the bottom of the front gear (SRAM 32T EAGLE XSYNC 2). But I see no obvious wear on the gear. So I guessed the chain is worn, too long again which I can see would cause that, so I got a new one. SRAM XX1 EAGLE 12-speed, £81. Cut it to length to match old one (117) and put it on. Immediately found it skipping not just the bottom gear but also the next two.

In the belief the chain is too long, I removed 1 link from in and it made no difference. But also the gearchange was not working as before and needed adjustment (why??) but I could not get it right. So I thought; maybe I need a new casette again, but they are 200-300 quid and I've been using the gears much more evenly than previously.

Eventually I gave up and 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. I also bought that adapter with the 4 pins to remove the centre nut; found it pretty loose and about to fall out. But it does not hold anything; it is just a threaded ring.

The bike had a service a couple of months ago! It was obvious the shop refilled the tubeless fluid via the valves, not removing the tyres to get the old stuff out. He managed to mangle one of the valve inserts as well... and returned the bike with a load of mud in the gears.

Can anyone guess what is going on?

Maybe these "modern" bikes really get through the bits so fast? 3hrs a week is too much? Hardly. It would cost maybe £500 a year in parts.

Maybe I bought the wrong chain? https://www.amazon.co.uk/dp/B08B2QYB48
Maybe over-oiled? Maybe there are many subtly different parts?

I have a bench clamp for the bike so can work on it easily enough, but I probably don't have the special tools for removing the rear casette.

Could be that the parts are made to very close tolerances and need to be set up exactly right. But how? How the gearchange works is obvious and should be adjustable visually.

Previous bike was a Sunn Shaman, 26" wheels, had it 10 years, never replaced anything, ran perfectly. Half the price of this YT one.

Thank you for any ideas.

I'm not a SRAM user. But some of their 12 speed chains don't work on 11 speed rears. I didn't see that you said what rear that bike has on it.

All chains for bikes today and for most of the past, have a 1/2 inch pitch chain. On some SRAM and maybe even some other brands of 12 speed drivetrains, it was the roller size that changed. Not the pitch. And the external width has periodically changed also.

So when you say the pitch of your old chain was longer, I assume you mean it was worn and maybe a 1/6 inch longer at what should have been the pin or other measuring reference the origin of your scale was on when checking if it was longer than 12 inches.

Chains shouldn't wear out too fast. But I don't know what 3 hours a week equates to in mileage. I have a 11 speed chain with over 8000 miles that many here are in disbelief of .

2000 miles of chain life might be reasonable if you tend to pedal a slow cadence and muscle the bike up hill in a hard gear instead of shifting to a ridiculously easy gear and pedaling up that hill at 90 - 100 cadence rpm. IMO

You also might make certain that all your drivetrain is running compatible stuff. And since you are having issue, if no other member here gives you any solution, then go back to a chain and cassette from the maker of your chain ring. And make certain they are all shown as compatible. Not all are.

The rear is 12 speed.
The new chain was made to exactly same length as the old one.
By "longer" yes I meant just by the amount of wear, so perhaps a few mm over the whole length, when stretched.
I have been trying to buy SRAM EAGLE parts; are there incompatible variations within this?
The "chain suck" is something which started only recently, and is on the old chain. The new chain just slips on the lowest 3 gears, under high torque (standing on the pedals).

is the front ring a "Narrow-wide" design? do you understand how to clock the chain onto it?

https://mtbdatabase.com/bikes/2022/y...t-izzo-core-3/

and, for the record... you can't "remove one link from the chain" unless it's the quicklink, which will be needed to re-assemble the chain.....

i'm still trying to wrap my head around a 70 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...

No idea about "clocking". The new chain runs fine on the front gear. Googled it and found nothing.
These pics are with the old chain back on, which runs ok (apart from sticking a little on the bottom of the front gear; started only recently).
The new chain was the same number of links as the old one. Yes, it is obvious you cannot remove just one link; you can do only in twos. Is the chain I bought wrong? I posted a URL to it.

if the cassette is new, as in REALLY recently replaced, then you need to service the freehub ratchet.. it uses a special weight of grease, not just whatever axle grease you have...

and thank you for the added info..

Why would the freehub ratchet cause this, when it happens only when under power?

Thinking about it again, the rear casette was replaced about a year ago. They are very expensive! But I don't have a casette problem (once back on the old chain).

this is a recurring problem, spanning two bikes.... i'm out.
and, for the record... SRAM drivetrains are a problem waiting to cause questions.
i just went thru one such problem last month... repeated backpedal derails/jams on a 12sp. NX eagle.
the "New Flat Top Design!" chain SRAM said would solve the problem only partially helped.
good luck, peter.
PS, as a Co-Op shop owner, i shop for used parts frequently.. and a Way out-of proportion number of SRAM parts show up as "New take off" and "lightly used".... hint, hint.

https://www.pinkbike.com/forum/listc...hreadid=221000

Are you sure you don't need a "flattop" chain? SRAM XX SL Eagle T-Type Flattop Chain (Silver) (12 Speed) (126 Links) - Performance Bicycle

the chain on the bike now appears to be, possibly, installed upside down too... it might just be the amount of built up filth on the chain, though... at least pete's lubing his chain now!

cogs 8 to 12 appear to be hooked/worn, but that may be a SRAM design element...

Does your RD have a clutch, that possibly might have been moved to the disengage position?

To check your chain for wear, measure it with a tape measure, scale or what have you.
The longer the length you can measure, the better resolution.
I can only handle a 3' long piece without feeling I might compromise accuracy.
IF you have a helper, measure a 5' section.
Chain wear is measured in a %.

Per Sheldon RIP-
https://www.sheldonbrown.com/chain-wear.html

• If the link pin is less than 1/16" past the mark, all is well.
• If the link pin is 1/16" past the mark, you should replace the chain, but the sprockets are probably undamaged.
• If the link pin is 1/8" past the mark, you have left it too long, and the sprockets (at least the favorite ones) will be too badly worn. If you replace a chain at the 1/8" point, without replacing the sprockets, it may run OK and not skip, but the worn sprockets will cause the new chain to wear much faster than it should, until it catches up with the wear state of the sprockets.
• If the link pin is past the 1/8" mark, a new chain will almost certainly skip on the worn sprockets, especially the smaller ones.

Translate mark to 1 foot.

Sram SX and GX chains are made of cheese and wear extremely fast.

The X01 and XX1 seem to last forever.

I wore a GX cassette out in a season with the chain the bike came with
Replaced the cassette with the same exact one but switched to XX1 chains and over 2 or 3 seasons it's barely showing any wear.

It does not span two bikes; I don't understand.

Yes I saw those "worn teeth" but they seem to be just a design feature.

The old chain is not flat top. Nor is the new one. The new one says XX1 on the box.

Interesting guide re chain stretch. I have measured it. On 1ft, the old chain is exactly 1/16" elongated. This is measuring it under tension.

The mystery is why the new (XX1) chain simply does not work at all. Maybe XX1 is no good for this bike? That link (no pun intended) points to a $180 chain and that would be a great way to find out it is a wrong chain

This is the old chain. SRAM EAGLE 352 and it has worked perfectly for a year, until it started sticking to the front gear at its bottom.


I have always kept stuff well oiled. Some say too well because it attracts dirt. So I tend to wipe the outside of the chain after lubing. I use the expensive Miuc-off lube, mostly the wet version.

I did a google on the 352 and it says it is just an internal SRAM code and "If you are replacing your chain, any SRAM Eagle 12-speed chain (NX, GX, X01, XX1) will work with any 12-speed Eagle drivetrain." The 352 means nothing. So it says the XX1 chain should work but it totally does not.

But surely if the new XX1 chain needs a new rear cassette after 1 year, with the old chain worn to 1/16" elongation, that is ridiculous given how much they cost: £75 to £380 (for X01), and reviews suggest the cheaper end is trash. I checked for any correspondence and 1 year ago the front gear was £50 and the cassette was £170, which probably tells you what they are. Reviews of SRAM suggest the £170 parts are junk.

Just done a 1hr ride back on the old chain. It now skips on the smallest gear too! But I can adjust that out with the adjustment on the gear selector (on the handlebar). So I think this skipping must be somewhat related to the derailleur. I have a Q:
Obviously the upper derailleur wheel needs to be exactly aligned with the appropriate gear on the cartridge. But does the lower wheel have to also be aligned the same way? Mine is slightly off, as if the derailleur was slightly bent towards the wheel. But the bike has never had any impact. I would expect the lower derailleur wheel to be slightly "towards the middle of the cartridge" so the chain is somewhat guided to/from the front gear.