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Suddenly during the ride, strange cracking noise started to happen. It happens even without a chain. The crank seems to rotate smoothly otherwise. There are more cracking noises when rotating forward. Much less rotating backward.

This is how it sounds when rotating cranks:

2 days ago there was a rain and I washed the bicycle. Otherwise nothing special happened what could be causing this. The bottom bracket is Race Face BB92, PressFit, shell 41x92mm.

EDIT: One day later it got even worse:

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  • To my ear the resonance and the timbre of the sound suggest a cable slapping the frame, rather than gnashing of broken bearings.
    – Sam7919
    Mar 19, 2023 at 9:26
  • @Sam Can it be related to just rotating the crank? The cable is inside the frame.
    – petrsyn
    Mar 19, 2023 at 22:53
  • Sure, the spindle and the two cables are inside the frame. It's easy to check. Gently push more cable inside the frame from the exit point(s). Does doing that change the nature of the sound? Pull, still gently, to remove the slack, and recheck. Also, when you touch each cable while turning the crankarms, you should not feel any vibration specifically on the cables if the sound originates in the bearings.
    – Sam7919
    Mar 20, 2023 at 2:39
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    @Sam unfortunately pushing or pulling inner cables has no effect on the sound or on the frequency of clicking.
    – petrsyn
    Mar 20, 2023 at 12:19

1 Answer 1

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That's an ominous sign you have a bearing going out or there is piece of debris (like a sand grain) that has infiltrated the bearings. Either situation can cause a bearing ball to "catch"--momentarily getting jammed and the noise comes from the jam releasing.

You'll need to remove the cranks to access the seals of the cartridge bearings. You can leave the cartridge bearings in place in the shell (although it would be best for thorough cleaning to remove them properly with an appropriate bearing press/extractor. Pounding them out or using a poorly chosen homemade press system risks damage to the bearing and leaving them in place is far better than botching the press out and back in).

Once you have access to the cartridge bearings seal, use a thin, sharp edge (like a utility knife razor blade, exacto knife, etc) to get under a part of the seal. Be gentle as you don't want to damage the seal or bend it's metal core. Once a little section of the seal circumference is out of its seat, a pick or the blade can be used under the seal going around the bearing, dislodging the seal from its seat. Using a spray degreaser product--most effective would be an aerosol can with a straw that can accurately direct a pressure spray into the bearing. Compressed air can help with clean out as well. Be mindful of blowing gunk and degreaser all over the place so eye protection is a must and you'll want to prevent contaminating your brakes and rotors. A shop rag covering the periphery of the bearing when your using compressed air is a good idea.

Flush, flush, flush. Use a tooth brush or small paint brush to remove clots of dirty grease. As the innards become cleaner, do your best to examine the parts within. With the metal cage in the way (don't try to remove it), it's hard to accurately judge the condition of the balls. Severe damage or missing balls is usually quite evident. Inspect as you clean. It may be that you'll have to replace the cartridge bearings, especially if they've seen a few seasons.

Check your progress by sticking your fingers in the spindle hole and rotating the bearing. There's a difference in a gritty feeling from dirt or damaged bearing balls and the slight, fairly uniform roughness of a cartridge bearing with grease washed out. Let the solvent dry for a time. Then use a grease filled syringe or grease gun to infuse clean, waterproof grease back into the bearing. I usually hit 3 or 4 spots along the ring, spin the inner bearing race and repeat until the cartridge is full. When replacing the seal, be attentive they edge of the seal is seated properly around the entire circumference. Ideally, there will be no gritty feel whatsoever in a cartridge bearing filled with clean grease.

Here's what you're up against as well. Based on your video and the info provided in your question, you have a Raceface Next crankset that has a 30mm spindle within a PF92 bottom bracket. That particular bottom bracket standard was designed around cranks with 24mm spindles. With the smaller spindle, there is room for larger bearings. Larger bearings in this situation are more durable. With the 30mm spindle, the compatible bearings are much smaller, making them prone to premature wear and sensitive to contamination. Bearing problems are often noted in PF92 systems compatible with 30mm spindles.

A second situation that I would be concerned about with that noise, is a published history of the Raceface Next cranks, which are carbon fiber, to encounter issues related to the aluminum inserts for pedals becoming loose. In addition, the bonding around and involving the spider or cinch ring can become compromised. The timeline for the most of these problems to occur seems to converge on the 3 year mark. I don't mean to degrade the Raceface Next cranks, which are very light and very expensive, but the aforementioned problems are undisputed facts (bearing size in 30mm compatible PF92 BB's) and frequently encountered anecdotes when querying for general information on Raceface Next cranks, including owner reviews posted on the Raceface website.

Inspect the cartridge bearings and determine when they should be changed out for a fresh set.

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  • I would not bother with such a process. Just replace the BB cups. Mar 18, 2023 at 18:43
  • Thanks for taking the time to reply Jeff. I took one crank off and put it back on and the noise stopped when I turned it by hand. I'll see tomorrow when I ride the bike if it happens again.
    – petrsyn
    Mar 18, 2023 at 22:17
  • Unfortunately after 20 minutes of driving the clicking started again as before. I will visit a bike service to fix it. I don't have enough experience to fix it myself. Anyway, thanks for the advices.
    – petrsyn
    Mar 19, 2023 at 22:45
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    Despite their sealed design, modern cartridge bearings--especially those of external bottom brackets-- aren't seeming to hold up as well as earlier versions of bottom bracket bearings. The BB system where the bearings and spindle were enclosed in a housing with the right side cup (cartridge bearings bottom brackets) lasted multiple seasons without issue. As far as external bearing BB's, I've had the best luck with Shimano branded ones. My current Stumpjumper has a thread together BB with Enduro bearings. They become contaminated extremely fast, forcing service 2x/year.
    – Jeff
    Mar 25, 2023 at 21:26
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    @petrsyn Happy riding. Glad the issue was solved.
    – Jeff
    Mar 25, 2023 at 21:29

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