Ultegra 6800 Chainrings Worn after 8000?

Mountaincoffee

Hello,

I have just replaced the chain on my bike as it was showing .75% wear. I check my chains weekly, keep clean and lubed etc.

When I went for a spin I started to get jumping from the chain when I was in the big ring using the largest sprockets at the back, not the largest as I don't cross chain but the 3/4/5 and whenever I came to put power down hard the chain would jump off the front chainring onto the crank arm.

I checked the FD alignment and it' fine and the gap between the fd and chainring is as small as it can be.

I'm coming to the conclusion that it's a worn front chainring but it has only done 7600 miles which I think isn't too great for a 11 month old Ultegra 6800 unit.

I run a full Ultegra Di2 setup and look after it meticulously. The cassette is 4k old but it's in good condition having never been run with a stretched chain.

I have tried the chain slack test lifting it up whilst on the rings and there is pretty much none. WHat do you guys think of these chainrings?

sextoke1

I have 6870 like you. I aways check the calibration after changing any one component. I down loaded the dealer booklet and I carry out a fine tune of the FD and RD and then do the electronic calibration with the button on the junction box. I have done 15,000 km on this bike and have two cranksets (winter and summer) and just have moved on to my third cassette, only after getting a checker tool which said they were worn. At that point I still had no problem shifting, and I would say that I would be a heavy duty operator on a bike.....If you can not sort it after a fine tune, and you are happy that you have not bent the hanger, you may look to change the cassette.

Mountaincoffee

Thanks for your reply. The cassette visually looks good and I can't find any chain slack on the cassette but I have ordered a replacement. I think it is a problem with the rings though. The slipping appears to be coming from the rings.

-Dash

adamr100 wrote:

I have tried the chain slack test lifting it up whilst on the rings and there is pretty much none.

I don't mean to hijack your thread at all but wondering what this test is? I have a similar issue after changing a chain/cassette with the large chainring. Although, I struggled to test the inner chainring at high power besides holding the front brake on and trying to put a lot of power down.

Mountaincoffee

-Dash wrote:

adamr100 wrote:

I have tried the chain slack test lifting it up whilst on the rings and there is pretty much none.

I don't mean to hijack your thread at all but wondering what this test is? I have a similar issue after changing a chain/cassette with the large chainring. Although, I struggled to test the inner chainring at high power besides holding the front brake on and trying to put a lot of power down.

No worries. It's more of a test to check chain length but basically you try to lift up a chain link whilt it's on the ring. If you can get it far enough off your chain is stretched. Like this: https://cdn-cyclingtips.pressidium.com/ ... ips-41.jpg

-Dash

adamr100 wrote:

-Dash wrote:

adamr100 wrote:

I have tried the chain slack test lifting it up whilst on the rings and there is pretty much none.

I don't mean to hijack your thread at all but wondering what this test is? I have a similar issue after changing a chain/cassette with the large chainring. Although, I struggled to test the inner chainring at high power besides holding the front brake on and trying to put a lot of power down.

No worries. It's more of a test to check chain length but basically you try to lift up a chain link whilt it's on the ring. If you can get it far enough off your chain is stretched. Like this: https://cdn-cyclingtips.pressidium.com/ ... ips-41.jpg

Ahh I see. I tried that with mine this morning and there was a fair amount of gap... though it seemed I was just pulling the derailleur a little bit too. Anyway, I chucked a SS derailleur and new hanger on as I had them lying around and I've changed the cassette from 11-32 to 11-28. The problem seems to have gone now. I tried putting down a lot of power in various gears and the large chainring and all is fine so perhaps it was more the fact my rear derailleur spring is worn or an alignment issue.

In terms of mileage I'd suggest 8000 is a little too low to wear out the chainrings. Mine have done more than double that and I've only just changed the inner ring (which honestly probably got a bit more neglected during cleaning).

sebbyp

As you've just fitted a new chain, I would have a good look at that first. What chain is it? I think the HG701 chains which I use for the old ultegra di2 have to be put on the right way round with the shimano logo on the outside. Having said that, did you use a quick link or pin? Check every link to see if you can find a stiff link, driving the pin in too far will do this and cause big problems.

Other than that it is odd that it is falling off the outside of the crank considering you're saying it does it high up the cassette rather than low down. see how the chain sits on the big ring by looking at it from the front of the bike, not side on, When I destroyed a chainring from cross chaining the chain was visibly leaning one way and the teeth were sharp.


Let us know how you get on, I cant really talk as I just checked my chain and it is off the chart worn at least 1.25%