lyle.coop

I have a new Canyon Spectral and it's shifting just fine. Every now and then (2x a ride) the chain derails off the upper jockey wheel. I have to flip the bike over and get it back on the jockey wheel.

B-tension looks fine, limits are set, and cable tension seems fine as its shifting well.

Anyone have a similar issue? Solutions?

Thanks in advance.

FBinNY 

I assume (to void having to consider it) that this isn't happening when back pedaling. So, we need to look at how the chain moves and consider how it would be derailed where it's feeding from the idler pulley.

Most likely suspect is a bent or twisted cage where the pulleys aren't correctly in line. Also, just in case it applies, Chains sometimes derail from the bottom pulley when the RH hanger is bent, so the pulley is far off line from the chainrings.

The key to either situation is to accept that the bias is to staying on, same as with a sprocket, so always start by looking for a chain feeding on from a side angle.

maddog34

lube your chain... and quit upshifting so fast.

also.. those long teeth on the jockey wheels struggle to mesh with the chain.

and that chain has beveled edges that allow the jockey wheel to also derail, just like the cogs on the cassette do..... except the jockey wheels DON'T have the directional bias that the small cassette cogs have in their design... oopsy, huh?
possible cure: shorten the jockey teeth 1 or 2mm, and lightly radius their front and rear tips at the same time.
look at ALMOST ALL OTHER JOCKEY WHEELS as a guide... big tall squared off teeth are not a very common design feature for really small sprockets in general, eh?

easy shifting chain = easy derailing jockey.
and do try to let Shimano know about this issue.. i've heard of it from someone else too. Note what situation causes the derails, what gear you were shifting from, or if it "just happened" out of the blue, or while BACK-PEDALING...... they'll want to know any details you can provide them with.

mpetry912 

check that the derailleur hanger is in plane - straight - not out of alignment.

you can eyeball it.

After that, chain tension

/markp

Polaris OBark

Canyon's derailleur hangers can sometimes become loose. Check it.

lyle.coop

1. It might happen when I'm back pedaling. I'm not sure. I'll try to be conscious of what I was just doing before it derails.
2. @maddog34 does the chain look too dry? I'll lube it. How do you know I'm shifting too fast? Can you see wear pattern on my cassette rings?
3. It seems to derail somewhere in the middle of the gear range. Definitely not in the very high or very low end of gearing.
4. The hanger should be straight. It's a brand new bike, no crashes. I'll check though.
5. I'll check the derailleur hanger bolt. I checked it the first time it derailed. Haven't checked since. I did notice the rear wheel was loose after my last ride. But the wheel was tight when the chain derailed.

Hondo6

This may or may not be related to your RD pulley issue. But finding a loose wheel that was previously tight seems like a significant red flag to me.

Not familiar with that model bike. QR or thru-axle? (I'd guess the latter but don't know if that's the case.)

Either way, I don't think you should be finding wheels loose post-ride.

Iride01 

Is that last picture your actual bike and DR? Looks like the jockey wheel might be too far from the cog. Can you adjust it closer with the b-screw?

curbtender

https://1drv.ms/v/s!Au6fgvSbB56Ui1qqYdh0eWs9rNHj
Is the clutch on? If not, it would bounce around a lot on the smaller cogs.

maddog34

#2... "too fast" as in too many gears at once... I've had a shifter in the shop that was going from bigger to smallest every time the release trigger got clicked.. it would derail and lock up the chain when it did so across 3 gears or more.... a pawl spring had failed in the shifter... Not saying that's the exact case with your problem.but dropping too many gears at once can and does cause derails...
Regarding #3.. i've seen a sticky cage pivot cause a momentary slack chain...could there be a ding on that pivot? "new" or not, check EVERYTHING, is my diagnosis procedure... check that lower knuckle and the cage's operation for any resistance other than the spring....

i'm quite serious about those unusually long teeth on those jockey wheels... that stands out as a possible source of trouble.

Check the B-screw adjustment... if it's not correct, the jockey wheel might be out of position relative to the cassette cogs, allowing that annoying derail to happen... i like to align the paralellogram to the incline of the cassette for best operation of the der.... the middle parts of the der. should align front-to-back, or "flat, not leaning" as one buddy says... there are actual B-screw adjustment specs for jockey wheel distance from the cogs...

and lube that chain.. not stiff, heavy wax... use light, oily lube.. I just cleaned a chain last week that was lubed with heavy, sticky wax... it was extremely reluctant to shift until cleaned... it acted like it had a dozen tight links too.. it works fine now....

(To the chain waxer crowd.. we're trying to help the OP stop the derails, not endlessly harp about how long you think your chain has lasted.... There''s an active Waxer thread you can post in... this ain't that thread.. Thanks.)

maddog34

i've seen too many times where folks think that B-screw is a way to take up excess slack from a too-long chain.... sigh...
much like they think the limit screws will remedy a poorly adjusted shift cable or bent der. hanger... two more sighs...

and then, there's the spring preload screws on v-brakes.... Customer: "It looked loose so i screwed it in..now my brakes drag!" Me: how long ago did you "tighten" those screws?... Customer: "Last summer...".. bigger sigh, Lurch moan, face palm.

lyle.coop

Clutch is on.

Last picture is a photo from Canyons website. I think the rule of thumb is 4-5mm distance from the jockey wheel to the largest cassette. That's the distance I have. Even if i wanted to tighten that gap, the b-screw won't allow me to do that. One turn would have the screw so loose that it would back out on its own when I'm riding.




Pedaling backwards: There's definitely a clicking noise when I had the bike in the stand. I think this is the source of the problem. Not sure how to fix it.

• RE: Too fast - sometimes I'll shift 3-4 gears at a time when there is uphill terrain forthcoming. While I don't think that's what's causing my issue, I could see that being a problem for my shifter in the future. Thanks.
• I checked the cage pivot for stickiness. Seems ok. I'll check it again with the chain off.
• Unusually long teeth on those jockey wheels - maybe this is it. I'll going to try to eliminate other issues b/f I tackle resizing the jockey wheels.
• B-screw adjustment - to bring the upper jockey wheel closer to the cassette, I believe I need to loosen the screw. 1-2 turns on that screw and it is super loose. Maybe the problem is the opposite. Maybe the upper jockey wheel is too close to the cassette. I'll take a look later today.
• lube that chain - This is another likely culprit. I rode the bike with just factory lube on it. Went thru the bike and put a tiny drop on each pin. Seems to be running smoother. But I still have that click when pedaling backwards.

HEre's some pics of the derailleur and cassette alignment.

curbtender

Your cage is bent.

cny-bikeman

I may be wrong, but the pulleys look like they are not in line vertically, and it looks like I can see the side of one while looking down the centerline of the other. That woujld mean they are out in two planes. I've straightened bent pulleys before, but would tend to say replace the derailleur. Also I agree that no matter what you should check the hanger alignment.

maddog34

I'm seeing that too.. Top jockey wheel out of align?... Top leans towards the outside a few degrees, eh? Bottom one looks vertical, as it should be... couple that with those long teeth.. and a fast shift of more than one gear at a time.. and a dry chain.. With a POSSIBLE tight link or whatever making that "click".... Derail.

reset the B-screw to move the top jockey wheel a couple mm lower, away from the sprocket.. this will allow more chain flex to reduce derailling force...

then round off the tips of the top wheel's teeth...

lyle.coop

Ok guys I brought out the construction laser to verify. (sorry for the messy looking work space - the apartment is under construction).

It was tough to get the bike perfectly plumb, but I think I managed to get close.

I then shot a plumb laser down the center of the currently indexed cassette ring. The upper jockey wheel looks to be close (not perfectly) in line with the cassette ring. The lower jockey wheel is leaning inwards (closer to the spokes). I think the inward lean of the lower jockey wheel could influence the chainline towards the spokes. And this is indeed what is happening. The chain falls off the upper jockey wheel in the direction of the spokes.

Here are some pics. I did my best to label them.

Also I think the derailleur hanger is fine. I shot a laser line along the outer edge of the hanger and it is in line.

BTW, I rode the bike yesterday and it derailed - 3x. At least I've ruled out the dry chain.

What do you guys think?

curbtender

Something in the system would need to create slack to make it pull off the wheel. If the chain is in good shape, the clutch on the derailleur working proper and the cage and hanger not bent then I'm not sure where you would go from there other than a shop. That lazer shot made me woozy, lol. Good luck.

trojanman190

Was any resolution found?

I've got a brand new Fezzari Delano Peak with SLX and its exhibiting the exact same behavior. A few times per ride, when shifting through multiple gears quickly, the chain jumps off the upper pulley. I've got less than 250 miles on the bike and I'm good about keeping everything clean and lubed. It started doing this maybe in the past week or two. I've had no crashes or anything.

Naturally it only started doing this after declaring a-loud to my bro that this drivetrain was way less trouble than the SX eagle I started riding MTB on

Doofus3000

I ride a lot... I've had 3 different bikes with new Shimano 12 speeds & all 3 do exactly this.Even when tuned crisp.

It's not every ride, but every couple. Happened in a race in the home stretch & i pedaled through it since it didnt lock up & basically sawed the derailleur in two.

I notice that the hanger bends a few mm towards the spokes, causing misalignment. Almost like the hanger is bent, but it isn't. when you disengage the clutch for maintenence and swing it into position, and the chain tension is present, that is when it bends a few mm out of alignment.

it's tough to say because the cage isn't exactly straight. Has a funny bend to it stock.

i think the guy pointing out the teeth on that jockey wheel could be on to something.

I'll likely try Sram Transmission next bike to get away from it.

Pain in the ass.

Kontact 

These need to be run with an 8mm gap between the largest cog and the jockey. Is that happening?

Doofus3000

With Shimano 12spd, they provide the b-gap indication marker on the derailleur to align with the cassette tooth.