LMT’D Front Sprocket Dropping Chain

[rpr]

Just took delivery of the bike and got it assembled. It’s dropping the chain off the front sprocket on the bike stand as well as when riding in 7th and 8th gears. The chain rides up off the front sprocket teeth and then slides between the teeth and the outside chain guard.

The chain is well lubed and the Altus rear derailleur is indexing well and the stops seem to be properly set. It occassionally happens in 7th gear before I even get to 8th gear so that eliminates the high level stop.

It does seem like the angle of the chain (when viewed from above) is a bit more than typical in 7th and 8th gears, which is effectively pulling it off the front sprocket, but that’s not adjustable.

The Altus rear derailleur doesn’t seem to have much tension so I’m thinking that may be the culprit, but I haven’t seen anyone else mention this as an issue.

Any thoughts/suggestions?

 

[procreator]

I'm not familiar with that problem, but the support at R1U is great. Reach out to them.

 

[rpr]

Found and fixed two stiff chain links, but the chain is still being dropped by the front sprocket in gears 7 and 8.

Does anyone know if the chain that comes on the LMT’D is a Shimano directional?

 

[Rideagain]

Specs say it's a KMC. I'll check when I put it on the stand.

 

[Gionnirocket]

I'd still move the high level stop in until it makes noise at cog 8, then back it out a quarter turn.
Possible that the chain wasn't sized correctly? Or too long?
If everything checks out... These work well. You can cut the outward plastic away so that you can still use the outside chain guard and it'll still keep the chain from rising up

https://www.amazon.com/CYSKY-Mountain-Chainring-Perfect-Aluminum/dp/B082KFBFS1/ref=sr_1_1_sspa?crid=14JWJI009UPUC&keywords=Chain+guide&qid=1670936789&sprefix=chain+guide%2Caps%2C135&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyR0hJWFNZRUhYV1lFJmVuY3J5cHRlZElkPUEwMjA5NzI4M084MU9RVjlMN1ZCMSZlbmNyeXB0ZWRBZElkPUEwNjE4ODg3M1RCSVBTV1FNN0NXNSZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

 

[Rideagain]

Chain info...
KMC Narrow, Z8.3, Z, 1L
Have no idea what the Z or 1L means.

 

[Gionnirocket]

Chain info...
KMC Narrow, Z8.3, Z, 1L
Have no idea what the Z or 1L means.

Z is the design shape of the outer plate
1L (I'm guessing) comes with 1 missing link

 

[Rideagain]

Thanks. Chain has multiple 1L links???
I haven't looked up KMC yet so hopefully they can explain it. I'll post what I find.
Thanks.

 

[Rideagain]

KMC Z8.3 chain.
Size: 1/2"x3/32"
Length: 116 Links
Weight: 305 grams

This is all I could find on their website. They only use facebook and instagram for contacts and I have neither.

 

[Gionnirocket]

Thanks. Chain has multiple 1L links???
I haven't looked up KMC yet so hopefully they can explain it. I'll post what I find.
Thanks.

No ... 1 L means the chain comes with one (1) missing link.

 

[Rideagain]

Thant's if you buy one. As it comes from R1U, no missing link could be found. I checked both sides. I'll check again. I've been known to look straight at something and not see it. Happens to my old eyes.

 

[Gionnirocket]

Thant's if you buy one. As it comes from R1U, no missing link could be found. I checked both sides. I'll check again. I've been known to look straight at something and not see it. Happens to my old eyes.

Very possible they buy bulk chain on a reel and cut to length and set a pin.

 

[rpr]

Still no luck in getting this resolved. Stiff links were fixed, slight wobble in chainring was fixed, no bent teeth apparent, and I’ve run through the derailleur adjustments numerous times. The chain still gets dropped/thrown not only in Gear 8 but also in Gear 7.

I’m starting to think it’s a frame alignment issue. Cumulative effects of slight manufacturing tolerances in the bottom bracket angle and the rear triangle securing the rear wheel seems to have resulted in there being a fairly severe chain angle where it enters the front chainring.

Here’s a pic of the chain angle as it enters the front chainring while in 8th gear from another LMT’D owner who was kind enough to share (chain angle as it enters front chainring is barely noticeable):

And here’s what that chain angle in 8th gear looks like on my LMT’D taken from the same perspective:

 

[rpr]

Just so you guys know we confirmed this was a frame alignment issue. Pretty obvious if you look at the above pics. The bike could have taken a punch while in transit or it could simply be the cumulative effect of frame manufacturing tolerances. No amount of band aid’s would have corrected this. Frustrating but Ride1up has been great. New bike is on the way.

 

[Rideagain]

Got my fingers crossed on the new one.
Geeze.. ya been through the ringer on this one. The new one will be perfect!

 

[PedalUma]

Last week I needed to put a spacer between a cassette and frame on a bike. I was also thinking bent derailleur hanger. It is good you are getting another bike.

 

[rpr]

Just figured I would let you all know that the new LMT’D was delivered and assembled today and all is well. It was definitely a frame alignment issue on the first one. Ride1up took great care of me to make it right. Now I just need this weather to pass so we can get out and ride a bit.

 

[PedalUma]

@rpr, Did they instruct you to put the first one into the box the second arrived in with a shipping label? Or do you have a second bike for spare parts now? I am glad that they made you whole. I think EBR influences that kind of follow thru. People talk.

 

[rpr]

Ha, nope, no second bike for spare parts. First one is headed back.

 

[Rideagain]

It would be nice to know what they find and avoid this from happening again.