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No, not asking about creaking :) On my gravel bike with Campagnolo Ekar (press-fit BB) after removing the chain from the chainring, when spinning the cranks they spin only for a few seconds (I heard that means the bearings are correctly greased) and I hear a faint, steady "rattling" noise. It sounds almost like an internal gear hub when running or a dry chain. Here is a short video demonstrating the noise (disregard the husband whistling in the backround). The video exaggerates the noise somewhat, it's almost impossible to hear with the chain installed, as it is drowned out be the regular drivetrain noise. However, in comparison, the square-taper BB on my other bike is completely silent without the chain.

Is this normal? Should I take it apart to see what's going on? This was immediately after a ride in the cold (around 0 °C), could it be possible that the BB shell contracts due to the temperature and compresses the bearings?

The bike was bought last summer, and I rode it for about 1000km in all weather (with mudguards in winter), including snow & road-salt, rain, and on various dirt tracks. I never used a pressure washer or garden hose to clean it, only a shower with low pressure. I didn't do any crazy jumps, only a few high-speed downhill bunnyhops over potholes.

Update:

I removed the crankset. The bearings don't spin freely at all, particularly the drive-side one requires some force to turn. Turning the bearings I feel some distinct "latching", like turning a rotary encoder button on some electronic gadget, or like turning the axle of a dynamo hub (but much weaker). The "latch points" occur in regular intervals (a few degrees), so I don't think dirt is the cause. In contrast, e.g. the axles of the wheels turn completely smoothly inside the hub (but don't spin freely either). I don't think this is normal for the bearings? Can pitting be the problem?

To my untrained eyes, the bearings look OK:

The BB cups are clean as well:

Update 2:

I contacted the manufacturer. They suspect the BB cups were not pressed-in correctly and are out of alignment, which in turn damaged the bearings. I will have the BB cups pressed in again to re-align them, and the manufacturer will have Campagnolo replace the bearings. If the problem re-appears after the next 1000km, the frame might get warrantied. However, they also confirmed that Ekar cranks always only spin for a few seconds because of the seal, so that part is normal.

Update 3:

A year and several thousand kilometers later, the problem hasn't reappeared. So the frame and crankset itself are fine, and either the bearings were defective from the start or the BB cups weren't pressed in correctly.

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  • Any chance there’s an internally routed cable rubbing on the crank spindle? You could try removing the cranks and spinning the bearings by hand to inspect for roughness.
    – MaplePanda
    Jan 28, 2022 at 19:09
  • @MaplePanda No, there is a plastic sleeve inserted between the BB cups to prevent exactly that. The rear brake hose and also an electric wire for the tail light are routed through the space between the BB shell and that sleeve. I will remove the cranks and post an update...
    – Erlkoenig
    Jan 28, 2022 at 20:42
  • Ultimately, if it bearings are dead inside, it does not really mater how exactly. Well, it only matters for the warranty, whether you are entitled for a free repair or not. But other than that it is just a bearing that needs replacing. Jan 29, 2022 at 17:27
  • Of course, but I'm not totally sure that the bearings are indeed broken and aren't supposed to behave this way... And it would be good to what, if anything, I did wrong and how to prevent this from happening!
    – Erlkoenig
    Jan 29, 2022 at 18:14

2 Answers 2

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The question was updated to include:

The bearings don't spin freely at all, particularly the drive-side one requires some force to turn. Turning the bearings I feel some distinct "latching", like turning a rotary encoder button on some electronic gadget, or like turning the axle of a dynamo hub (but much weaker). The "latch points" occur in regular intervals (a few degrees), so I don't think dirt is the cause. In contrast, e.g. the axles of the wheels turn completely smoothly inside the hub (but don't spin freely either). I don't think this is normal for the bearings? Can pitting be the problem?

When you rotate the axle or the bearing race, if it feels gritty, that usually indicates wear or contamination. For what the OP now describes, I believe the usual English term is that the bearing feels notchy or that it is binding. That can be caused by the cup or Bb shell being out of round, so that the bearing is compressed at some points in the rotation. In systems with preload, e.g. headsets and cup and cone hubs, if you tightened the system too much, I think it would also feel notchy.

Right now, without being able to examine the whole system, I’d guess that the bearing is the issue. In general, when you press bearing cups into a frame, you need to make sure that they go in straight. You also don't want to hit either of the races too hard. This is why we would use bearing presses and drifts - it is definitely possible to just use a block of wood and a hammer, but you do run an elevated risk of damaging the bearing. It is possible that somehow, at the factory, the bearing wasn't properly installed onto the crank half spindle, and it got damaged that way. This would be atypical of any high-end product, but any industrial process will produce some bad units, and quality control will catch most of them but eventually, something has to slip through the cracks. Your frame could possibly also be out of tolerance (e.g. that side of the BB shell isn't round or parallel to the other). Now that you've removed the crankset, I'd normally expect the bearing to turn normally. However, given the length of use, it's possible that this was the issue and that the bearing is now damaged. Unless you have the appropriate frame tools, checking that the BB is correctly faced and round is probably a shop endeavor.

Given the stated symptoms, I would get a bike store’s help to diagnose the issue, preferably one where the mechanics have at least some Campagnolo experience. If you bought the group online, the store who sold it might have some ideas on what could have gone wrong, although their insight will be limited by not being able to see the system in person. The same is probably true of your country’s Campagnolo distributor.


In response to the OP's second update: I am guessing that the bike manufacturer thinks that one of the cups may have got pressed in a bit crooked. This will load the bearings much more than they were designed to and would probably account for the binding - which will damage the bearings. I'm not sure how common this type of failure is. I would have thought that the frame was the issue. A good bike shop should have the tools to check if the bearing seats are round, and if they are not misaligned (i.e. they have to be concentric and at the same angle, within a very small tolerance).

This YouTube video by Mapdec Cycle Works, a UK bike shop, shows them using a gauge on a second hand bike to show that the bottom bracket had a very slight amount of parallel misalignment - that is, the bearing seats weren't concentric. The difference was very small, but it was just enough to cause premature bearing wear. You could feel the crank shaft binding at some points in the rotation.

They discussed using a specially designed gauge to detect misalignment, and they were discussing taking it into small-scale production. This may imply that not all bike shops have tools like this to detect misalignment. I expect that shops have accurate calipers, so I expect they can tell if the BB shell is under- or over-sized, and possibly if it isn't round.


Last, some clarification on expectations about friction. The OP said above that

after removing the chain from the chainring, when spinning the cranks they spin only for a few seconds (I heard that means the bearings are correctly greased) and I hear a faint, steady "rattling" noise.

It is definitely normal for the cranks to only spin for a few revolutions on modern systems. Bearings have at least two mechanisms which produce drag. There's the drag of the rubber seals against the races. At very low load, e.g. spin cranks by hand, the bearings mainly experience this type of drag. A totally new BB may have more seal drag than a used one. The seals will break in.

When you're pedaling, you're putting well over 100 watts into the cranks. Now, most of the drag comes from the loaded bearings rolling on the races. This amount of drag dwarfs the drag from seals at riding pace. If you search around, you'll see people say you can't spin the cranks to see how much drag there is - this is why.

I haven't installed a crank in a while, so I can't remember for sure, but I don't think noise when spinning the crank is normal. There might be a faint whirring, but I would expect this to go away after some time as the grease gets distributed through the bearing. The OP might have noticed the bearing notchiness while spinning the crank by hand, although it may have been more obvious with the crank out and them rotating each inner race by hand.

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  • Thanks for your input, I had similar suspicions. Since it is a high-end titanium frame (and the manufacturer likes to show off its precision), I'd assume that the BB shell tolerances should be pretty good. I bought it as a complete bike, directly from the manufacturer. I contacted the manufacturer about the issue, as they would be responsible for warranty issues. I will post updates when I know more...
    – Erlkoenig
    Jan 31, 2022 at 10:17
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I do not think this is normal. Most likely, the bearings are dead and the bottom bracket needs replacing. Unfortunately, with press fit BBs this is mostly a task for a bike shop.

Normally, the bottom brackets are not serviceable even if they use some standard industrial bearings inside.

The reasons for the failure may be numerous, but I agree that 1000 km is quite little. It may be some manufacturing defect, it may be that the seals got damaged and let some dirt to get inside.

You may try to dismount the cranks and try turning the individual BB cups to find out if you feel any grinding.

reaction to the update:

Ultimately, if it bearings are dead inside, it does not really mater how exactly. Well, it only matters for the warranty, whether you are entitled for a free repair or not. But other than that it is just a bearing that needs replacing. It may be some sand in it or something made of metal disintegrated to some degree.

I'm not totally sure that the bearings are indeed broken and aren't supposed to behave this way... And it would be good to what, if anything, I did wrong and how to prevent this from happening!

They really should spin freely. But no-one can say what went wrong without examining the inside.

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    On this groupset, the bearings are fitted to the crank half-spindles, Campagnolo offers a replacement service, but after a measly 1000km? The service interval for lubrication(!) is 4000km! Being a gravel groupset, it's advertised as being specifically resistant to water and dirt. Well, looks like I got something to do for the weekend...
    – Erlkoenig
    Jan 28, 2022 at 11:10
  • @Erlkoenig OK, I do not know this system. I would try to claim the warranty, but it is always uncertain, whether it is a manufacturing defect or just a bad luck. Jan 28, 2022 at 12:17
  • I realized this is the new Ekar, I must admit I only watched some advertising preview video on GCN about this groupset. But I do not believe the sound is supposed to be normal and I think it will require a bike shop. At least while the bike is still under warranty. Jan 28, 2022 at 12:27
  • Okay, thanks... I will take a look inside and decide whether to get warranty. Not going to be fun with the parts shortage. I got the bike directly from the manufacturer, a local "boutique" company...
    – Erlkoenig
    Jan 28, 2022 at 13:43

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