Hello,

One of my bikes has an eccentric bottom bracket with a Gates belt drive and a Shimano Alfine 11 IGH.

For a few days now, I've experienced some creaking noise when pushing on the right pedal. Even removing the right pedal, cleaning it, greasing it, and putting it back on didn't solve the issue.

So I figure I should do the same thing with the chainring, but I don't know how to do it: After using a 10mm Allen key followed by an 8mm Allen key, I could successively remove the two screws on the left side (shown as "1" on the picture), but then, I'm left with empty space where a standard bottom bracket axle lives.

Should I use some specific spanner to undo the rings shown at "2"?

Thank you.

The 10mm allen key cap that covers the 8mm allen bolt must stay in place, that is essentially the crank extractor.

Reinstall and tighten the 10mm cap, now loosen the 8mm bolt. It will loosen and then feel tight again, the bolt is pushing against that 10mm cap to push the crank off.

That will remove the one crank arm, you will likely have to give the protruding axle a tap or two to drive it and the attached drive side crank out of the bottom bracket.

Now you will need an external bottom bracket tool to check/tighten or remove the BB cups that are tightened into the bottom bracket eccentric insert.

Lastly you will want to remove/tighten clean/grease the eccentric BB itself, it will have an allen bolt holding it in place. That particular one looks like it tightens from the side with another allen bolt, probably in one of those little holes. Even with the bolt loose it might seem stuck as it's a giant wedge, again slight tapping might be required.

Edit: fixed some words. Ignore the bit about the wedge style eccentric BB, this is a split shell clamping style. Generally the least creaky of the eccentric BB's, assuming those bolts are tight I would tend to think it was the crank, BB cups or chainring as you suspected.

Thanks much.

I don't understand the first part:

"With the 10mm reinstalled and tight HERE loosen the 8mm bolt, it will get loose and then tight again. Keep pushing through that and it will pull the crank off, the bolt is pushing against that 10mm cap to remove the crank."

1. Isn't there a comma missing at HERE, ie. "With…, loosen"?
2. After screwing the 8mm bolt and the 10mm cap on top of it back into place, how do I loosen the 8mm bolt since it's now covered again by the 10mm cap?

Incidently, the BB is indeed held by two Allen bolts at the bottom (please ignore the labels):

Maybe this will help.

Once the outer cover is in place the head of the crank mounting bolt is trapped between the inside of the crank arm and the cover. If you tighten the bolt it pushes the crank onto the spindle. If you loosen the bolt, it backs off crosses the space until it's pressing against the cover. Now as you continue to loosen the bolt, it presses the cover and jacks the crank arm off the spindle.

I'll admit the wording and punctuation wasn't the best...

Got it: Leave the outter ring in place, insert an 8mm hex key through the outter ring and loosen the inner bolt; It will will push against the outter ring and release the crank.

Once the left-side crank is gone, use a rubber hammer to hit the right-side (drive-side) crank and slide it through the cartridge.

But even after cleaning and greasing the cranks, I could still hear the creaking noise on the drive-side.

So I went ahead, and loosened the two rings (cups?) to remove the cartridge bottom bracket. Applying some grease did the trick. I also noticed a plastic tube sitting in the middle of the bottom bracket, between the two rings.

Thankfully, I didn't break anything, as this was the first time for me and no one at the workshop was used to cartridge BBs.

I noticed that when tightening the drive-side ring, at some point, it becomes loose again: Maybe the left-side ring takes care of keeping the whole thing nice and tight.

I've been riding this bike every day or so for a couple of years, so might get a new BB now that I know how to get it installed.

Thanks much for the help.