HELP! Something is not right when putting load on the smaller cog!

[Sind]

Hi,

I’ve posted before, but I’m going to start a new thread. This issue is driving me nuts!

I’ve got a new Canyon Strive with 12sp XT drive train.

Under toque on the lowest gear (smallest cog) the chain skips or at least I think it’s the chain. I do feel it gets worse after each ride.

The gears shift fine with no issues or noise when on the workstand. I’ve checked all the adjustments and it’s setup correctly. The bike has been to Canyon twice and the rear cassette and chain has been replaced.

How do I diagnose the problem and what could it be?

I was meant to go for a ride tomorrow

 

[steve_sordy]

A worn cassette or worn chain on a new cassette would have been my first suggestion, but you report that they are both new. Next step would be the freewheel and then a worn ring. Freewheels do wear, they also can get water in there and the ratchet springs corrode. Unless it's something in the motor, I'm out of ideas. Worn rings can slip, it just doesn't happen as often as they have to be quite bad. This would do it! (New one in the background).

That ring worked fine with a new chain on the workstand and on the street, but as soon as I put any pressure on, the chain skipped alarmingly. I didn't discover that until I was out on the trail with four buddies! By the way, that is a ring off an mtb, not an emtb

 

[Sind]

A worn cassette or worn chain on a new cassette would have been my first suggestion, but you report that they are both new. Next step would be the freewheel and then a worn ring. Freewheels do wear, they also can get water in there and the ratchet springs corrode. Unless it's something in the motor, I'm out of ideas. Worn rings can slip, it just doesn't happen as often as they have to be quite bad. This would do it! (New one in the background).

View attachment 126257

That ring worked fine with a new chain on the workstand and on the street, but as soon as I put any pressure on, the chain skipped alarmingly. I didn't discover that until I was out on the trail with four buddies! By the way, that is a ring off an mtb, not an emtb

Thanks Steve. The chain ring is 6 rides old, so I’m thinking it’s the freehub. I have no experience fixing these so going to take it apart and see if there are any damage

 

[E Bob]

id re check the derailleur and shifter adjustments, Sounds like the stop on outside, so check its inline when in top gear

 

[steve_sordy]

Thanks Steve. The chain ring is 6 rides old, so I’m thinking it’s the freehub. I have no experience fixing these so going to take it apart and see if there are any damage

Look out for tiny leaf springs behind the pawls. They push the pawls onto the ratchet teeth and keep them there for instant engagement. If the spring corrodes and loses its power, then suddenly you have no drive. The effect depends upon how many points of engagement there are still working, the general amount of gunk in the area and gravity. If things conspire against you and there are great forces at play, then it can slip.

How do I know all this? Because I had an e13 hub on my Norco Sight and a desperately poor seal design meant that a brand-new hub (with a five-year warranty) lasted about 700 miles. I ended up with three of them all under warranty. Once I had the third one fitted, I sold the bike (the buyer knew the history). It lasted another 700 miles, so he rebuilt the wheel with a different hub and never had another problem.

 

[James_C]

I had that once too, freehub springs rusted and filled with muck. Lost all drive.

They need taking apart periodically and cleaning/regreasing.

 

[Mikerb]

It seems unlikely to be a freehub issue if the problem is only in the highest gear (nb. Smallest cog is the highest gear!).
It also seems unlikely a lbs would fit a new chain and cassette without checking the limit screws settings and b gap. So what does that leave?
What is left is incorrect chainline either because the chain ring is the wrong offset or incorrectly fitted.....or possibly a rear wheel hub (not freehub) misalignment.

 

[irie]

My guess is that the XT cassette lowest cog is incorrectly seated.

 

[Mikerb]

My guess is that the XT cassette lowest cog is incorrectly seated.

....maybe...but on both the old and new cassettes??? Other potential causes include b tension, derailleur clutch and chain length any of which if wrong would give a weak chain wrap on the smallest cog.

 

[maynard]

Cassette is toast . Changing gear under load much?

 

[irie]

My guess is that the cassette lowest cog is incorrectly seated

....maybe...but on both the old and new cassettes???

The OP said ...

The bike has been to Canyon twice and the rear cassette and chain has been replaced.

... so yes, possibly.

 

[Sind]

id re check the derailleur and shifter adjustments, Sounds like the stop on outside, so check its inline when in top gear

I ran through and checked these twice over the weekend. The one thing I've noticed is while they run smoothly, I'm at the limit...err...of the limit screws.

 

[Sind]

Cassette is toast . Changing gear under load much?

Decent load as if I start off in the smallest cog, but not unexpected on an eMTB. The cassette is new

 

[Sind]

The bike is booked in with Canyon for them to sort this out and no riding for a few weeks, which is a shame. Thanks for all the comments everyone. Hopefully, this gets figured out and I'll share what it was (if its fixed).

 

[Tribey]

Quick link the wrong way around?

 

[cozzy]

B tension incorrect giving not enough chain wrap on the smallest cog?
They are 10t (?) So if the b tension is too great, there may only be 4 teeth engaged with the chain.

 

[stratosa]

B tension incorrect giving not enough chain wrap on the smallest cog?
They are 10t (?) So if the b tension is too great, there may only be 4 teeth engaged with the chain.

You are absolutely right. I solve the same problem loosing the B screw all the way. Forget about the 51t mark.

 

[cozzy]

You are absolutely right. I solve the same problem loosing the B screw all the way. Forget about the 52t mark.

This was the only way I could get my recent linkglide to actually shift nicely was by ignoring the 48t mark on the derailleur which left a 19mm gap and winding it down to 10mm. Crisp shifting and bonus of more chain wrap.

 

[irie]

This was the only way I could get my recent linkglide to actually shift nicely was by ignoring the 48t mark on the derailleur which left a 19mm gap and winding it down to 10mm. Crisp shifting and bonus of more chain wrap.

That's interesting because recently I couldn't see the alignment mark on the (Deore 12sp/10-51) derailleur so in the end left about a 8-10mm gap which seemed to shift best with the chain just running freely.

 

[Stevewheels]

Maybe you missed a spacer when installing the cassette.
I had the same symptoms when after installing a whole new drivetrain on my bike. Just out of luck I looked at the box and noticed something rattling around in there. A spacer. Bingo.

Good luck.