New chain, skipping under load, MTB

[NHAero]

I ride a Pivot MACH429C equipped with SRAM XX1 drivetrain. I check the chain wear weekly. Last week the 0.5mm slipped in for the first time, so I put a new chain on. Yesterday, in the big cog (42T) up a steep hill, it was skipping. No skipping in other cogs but the load isn't usually as high. Did i wait too long to change chains, and if so, what criterion is the right one?

[EricEstlund]

Check the wear on the rear cassette and front ring. If it went from fine to slip, and the only thing changed was a new properly sized chain, you generally will be showing wear elsewhere in the system.

General rule of thumb is regular chain replacements, every couple of chains change the cassette, every couple of cassette change the front ring. Conditions, how you ride, the combos you ride in, etc will all impact that.

[p nut]

Is the rear D adjusted correctly?

[Mikej]

If it’s only the one cog check lint screw and cable tension. If it were several of the mid range cogs skipping, it would be the cassette. Unless you are constantly in the big cog. Maybe try to re- torque cassette ring.

[fignon's barber]

If it’s only the one cog check lint screw and cable tension. If it were several of the mid range cogs skipping, it would be the cassette. Unless you are constantly in the big cog. Maybe try to re- torque cassette ring.


....also lubricate your cables.

[Red Tornado]

On my bikes, when I wear out a chain I always replace the cassette along with it. They wear together. Maybe a little overkill, but a good insurance policy against skipping. Fine tuning the rear derailleur might buy you a little time but IMHO that mismatch in wear will come back around on you eventually.
FWIW I replace front chainring (I ride a 1x) every other chain, because I can flip the narrow/wide chainring. If a 2x or 3x you can definitely get away with every other chain.

[HenryA]

Check the derailleur hanger alignment while you’re at it.

[NHAero]

Thanks for all the input. I brought it to a friend who is a mechanic, and it really helps to have one person ride while the other looks! It turns out the chain is riding up on the top of the teeth of the big cog then dropping back down. We eased up on the stop screw to let the derailleur move in a smidgen more, and tightened the cable a tad. No luck, still doing the same thing. Was going to check alignment of the derailleur but the bolt didn't want to come out easy, so I ordered a new hanger. I got the bike used and never have pulled the derailleur in 2-1/2 years of ownership. I have the bike laying on its side with some Kroil soaking in, maybe that will solve the bolt issue.
Still a bit baffled...

[John H.]

Was the new chain cut to same length as old one?

[NHAero]

Yes
Was the new chain cut to same length as old one?

[KVN]

How often do you replace chains?

On my bikes, when I wear out a chain I always replace the cassette along with it. They wear together. Maybe a little overkill, but a good insurance policy against skipping. Fine tuning the rear derailleur might buy you a little time but IMHO that mismatch in wear will come back around on you eventually.
FWIW I replace front chainring (I ride a 1x) every other chain, because I can flip the narrow/wide chainring. If a 2x or 3x you can definitely get away with every other chain.

[Red Tornado]

How often do you replace chains?
It's a moving target. Depends on mileage & conditions. I try to check the chain every time I clean my bike & swap the chain/cassette as soon as the wear has "crossed the line". I might be a little over zealous compared to others but given the chains role within the drivetrain, I prefer to err on the safe side.
Plus, since I run a single chainring, it also helps minimize wear on that a little bit.

[foo_fighter]

Have you lubed the chain? I've had something similar where a dose of NFS helped.

[NHAero]

I haven't added lube to the new chain, but will give that a try. Since we determined that the chain isn't skipping, but rather riding up on the big cog's teeth then dropping back down, I've adjusted the limit screw to allow the rd to move inwards a slight bit more, and adjusted the cable tension accordingly. When it stops pouring I'll test ride it. On the morning MTB ride today, the next cog (or any other) never skipped under load, so I'm now convinced this is not a cassette wear issue, especially since I'm not in the 42T very often.

Have you lubed the chain? I've had something similar where a dose of NFS helped.

[NHAero]

So far, no solution. I ordered an 11 speed KMC chain, because I'll use it regardless, so will see if the issue occurs with another chain.

[Dirtdiggler]

This happened to me last weekend.. Trek Top Fuel with XT. Second and third largest cog the chain would climb.. After cleaning the chain and rear derailleur and adding new stainless steel shift cable and housing it still resulted in the chain climbing. I also checked my rear derailleur hanger with the Park tool alignment guide.. What I did and you should try is to adjust the B screw inward. That worked for me.

[gdw]

Have you checked the cable for damage, a bend or kink?

[NHAero]

When you say adjust the B screw inward, do you mean to get the pulley closer, or farther, from the cogs? I did adjust it to bring the pulley closer, but maybe that's the wrong direction.
It's interesting to me that this is happening only under high load. At moderate load, the chains tracks fine and doesn't do the climbing thing.
Thanks

This happened to me last weekend.. Trek Top Fuel with XT. Second and third largest cog the chain would climb.. After cleaning the chain and rear derailleur and adding new stainless steel shift cable and housing it still resulted in the chain climbing. I also checked my rear derailleur hanger with the Park tool alignment guide.. What I did and you should try is to adjust the B screw inward. That worked for me.

[NHAero]

I haven't. This issue occurred with a chain change-out, so I wasn't thinking that would be an issue, and it shifts fine through all the cogs. After I try the new KMC chain, if that doesn't solve the issue, perhaps I'll change the cable, certainly a low cost experiment! Thanks

Have you checked the cable for damage, a bend or kink?

[NHAero]

Well...brand new KMC 11 speed chain, same issue, chain climbs up on top of the teeth of the largest cog and drops back down. Have move the RD in as far as I dare and taken up the cable slack but no luck. Similar with messing with the B screw. No obvious cog wear and no skipping under load in any other cog. Shifts fine. Suggestions?

[Ken Robb]

How many rings on your crank? Is this a recent problem on an older bike or is it a new build you just haven't been able to get right? Are the chain stays really short?

[gdw]

We had a rider experience the same problem with her bike on a recent backcountry trip. The bike had been transported on a rack that held the bike with an arm that clamped to the top tube. The arm attached to the frame right behind a cable stop and put a bend, kink, in the exposed rear derailleur cable. When the rider shifted to larger rear cogs the kink moved further into the housing and eventually caused enough friction to prevent the derailleur completely moving inward and seating the chain on the largest cog. We discovered the kink when lubing the cable, replaced it with a new one, and shifting returned to normal.

[EricEstlund]

After messing with it for a week you might want to just pop into your local repair shop and see if they can help you out. Local eyes trump internet guessing.

[NHAero]

My wrench friend and I have fooled with this - b screw, limits screw, cable tension, two different new chains - without success. Bike shifts perfectly until under high load on the big cog. Put the old chain back on, problem disappears.

So now I think, given that the chain just hit 0.5mm wear point, and the cassette may need to be changed with a new chain to stop the skipping, why not just run both as is until the shifting degrades in some way? The only other wear item is the chainring, which is the lowest cost part of the system.

[BikeNY]

The big cog on those SRAM cassettes are known to wear pretty fast.

[Tony]

The big cog on those SRAM cassettes are known to wear pretty fast.

This. Your big cog which is aluminum is worn.

[Dirtdiggler]

NH - possible when re-installing the older chain you might have installed the outside face in ? causing the unwear face of the chain/rivets to not climb the cogs ?

[HenryA]

Unless its just not affordable, fix it right. Replace the old parts with new, ride trouble free. Bikes are supposed to be fun.

[NHAero]

AFAIK, there is no directionality to SRAM chains.

NH - possible when re-installing the older chain you might have installed the outside face in ? causing the unwear face of the chain/rivets to not climb the cogs ?

[NHAero]

The only part that isn't fun is riding along worrying about ruining components. If the cassette is already "ruined" but shifts perfectly, and I just accept that when the bike no longer shifts perfectly that I'll need to swap out the entire drive train, then the worry goes away and it's 100% fun again! Plus, I already bought two new chains :-)

Unless its just not affordable, fix it right. Replace the old parts with new, ride trouble free. Bikes are supposed to be fun.

[CiclistiCliff]

Replace your cassette. You probably live in the 42.

[NHAero]

Multiple companies make replacement big cogs for the XX1 cassette, because the big cog is aluminum and wears out faster. So I ordered a 44T at 1/4 the cost of a new cassette.

https://www.wolftoothcomponents.com/collections/cassette-cogs/products/gcx-44t-cog-for-sram-xx1-x01-cassette

https://www.oneupcomponents.com/products/x-cog-44t-sprocket

[NHAero]

I installed the aftermarket Oneup cog. It took about 15 minutes, flat bladed screwdriver, and channellocks with the jaws wrapped in duct tape so as not to gouge the aluminum. I opted for the 44T instead of the stock 42T and it doesn't shift quite as awesomely with the larger jump - not sure I would have noticed if I'd started with the 44T oringinally. I can't make the chain repeat the climb-and-skip problem, so it looks like a worn big cog was the issue.