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I have a bike with a Shimano Tourney 2x chainset (this one) and the plastic cover that sits on top of the outer chainring has started to creak whenever the driveside crank is under load.

Is it safe to remove the plastic all together? Will it cause any issues if I do that?

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    Are you 100% sure it's the plastic cover creaking? I would almost guarantee it's bottom bracket bearings if it's only happening when the drive side is under load
    – Hursey
    Jun 23, 2023 at 1:53
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    @Hursey or a loose crank, or failing pedal bearings. I've had both of those creak in the last few days
    – Chris H
    Jun 23, 2023 at 9:31
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    @Hursey, it turns out you were right! My bike was fitted with plastic BB cups, and the drive side one had come a little loose from the cartridge, making it creak under load. I knew it was a plasticky creak, I just didn't think that the bottom bracket would be made of plastic! Jun 27, 2023 at 13:08

2 Answers 2

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At first it seemed to me that the cover of that model is there mainly for visual purpose, as its diameter is smaller than the outer chainring.

enter image description here

But then I discovered that your model, on the plastic guard also has a plastic pin in between the crank arm and the chainring. Its purpose is to prevent the chain from doing damage to the crank arm or chainring should it slip over the big ring. In case the limit screw is not adjusted properly, for example. So it has a safety purpose, other than visual aspect. Removing the plastic cover would also remove this safety pin.

enter image description here

I have to disagree that chain covers are there mainly to protect your clothing. They have other purposes too. Like the pin your model has. Or this model, for example, that has a bigger guard, and it protects the rider in case of a crash from the sharp teeth of the chainring, which can become "ninja star" as some people describe them:

enter image description here

Regarding the creaking noise. I would inspect the crank arms for cracks too. And the chainring fastners for looseness and play. I believe yours are rivetted. The bottom bracket can cause creaking noises as well, it's the usual suspect.

In reply to DoNuT's comment. Fair point. I agree with you, I've seen models where the pin is part of the crank. But this one seems to have the plastic pin as part of the cover. It's cheaper to make it like that I guess. Here is a picture with the cover completely removed: plastic cover removed

Note the pictures in my answer are from a Tourney Triple, OP has a Tourney Double, but I suspect this plastic cover is the same.

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    Are you sure that pin is part of the cover and not of the actual crankset? Shimano road cranks have the same pin and it is part of the actual crank, so why would they integrate it on a removable plastic cover instead of making it an integral part of the assembly? A cover is a cover and a pin is a pin but the either part's existence doesn't justify the other.
    – DoNuT
    Jun 23, 2023 at 8:54
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    @DoNuT I have updated the answer with a reply section and included a picture.
    – Robert
    Jun 23, 2023 at 9:16
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    I would say that bikes that are more likely to be crashed, are less likely to have these discs. The one time I managed to cut my leg on a chainring wasn't even a crash, but an awkward stop (a car pulling out on me as I was dropping off a kerb). That was on a hybrid that originally had such a disc, but the replacement crankset didn't - it was only fitted on the OEM version.
    – Chris H
    Jun 23, 2023 at 9:30
  • @Robert Lesson learned. Need to check but I'm pretty sure it is on the crank on my 7-speed Tourney bike which has a fully naked crank with chain guard all the way back over the stays. Well, it's not meant to be removed and it will probably handle the occasional chain drop. Even though I only had a single one on the large ring in 10 years.
    – DoNuT
    Jun 23, 2023 at 13:49
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It depends.

If you ride the bike using either proper clothing (not too loose trousers), or put your trouser leg into a sock, there's no harm removing any chainguards or chainring covers.

If you ride the bike with improper clothing, in that case you should use a chainguard. But a chainring cover is a very poor chainguard, it doesn't help much. So I'd say while it slightly decreases your safety (against damaging your trousers), it isn't fatal. Also, it's for the safety of your trousers, not the safety of yourself. As long as the freehub is working, if your trouser leg gets caught in the chainring, you simply stop pedaling and that's it.

A fixed gear bike would obviously be an entirely different kind of animal.

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    Thanks. To be honest the cover is almost exactly the shape of the chainring underneath, including all the cutout sections, so I don't think it's really doing anything to protect my trouser leg from the ring. Jun 22, 2023 at 18:07
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    Also, it's for the safety of your trousers, not the safety of yourself. I can see trousers getting caught by the chainring causing a crash or loss of control, say by pulling your foot off the pedal while standing and pedaling hard. So I'd say there is a safety aspect, too. Marginal given riding a bike with "improper clothing" is almost impossible to protect against, but it's there. Jun 22, 2023 at 22:37
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    @AndrewHenle yes, I've had a couple of near misses from shoelaces and trousers coming free from their restraints. Long legs don't help - many trouser/sock combinations don't stay tucked in after I put my foot down a few times (one minor reason why I put my left foot down for preference)
    – Chris H
    Jun 23, 2023 at 7:49
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    Isn't most any clothing (or from my casual observation of World Naked Bike Ride Day, no clothing at all) "proper clothing" to ride a bike for ordinary purposes? I'll grant that we could conjure up some outfits that would be impractical, but there's nothing "improper" about riding a bike in ordinary loose fitting trousers. Jun 23, 2023 at 9:18
  • @ZachLipton indeed, it's just a matter of matching clothing, bike setup, and precautions. Even a word like "suitable" or "appropriate", while better, would be too much here without further qualification (that the answer does hint at).
    – Chris H
    Jun 23, 2023 at 9:22

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