My Tektro R539 brakes do work on the road: they obey to the brake levers at squeezing and releasing times. They do not behave to the mechanism to open them (for wheel removal for instance), they do not spring back (= open wide) when I open them. As if the spring is unable to open.

Outside of minor maintenance (centering and aligning the pads) I have not touched them, except for scrubbing the dirt from the spring with a metal sponge (I was using it softly). I also may have touched the lock plastic thingy (see https://www.tektro.com/products.php?p=44) without intent. I have tried putting some WD40 on the cables, to no help. It's odd that until very recently the brakes had no problem opening.

Should I refrain from cycling until I fix this?

Image from linked product website

Edit, here are pictures of the brakes and cables:



Edit 2: I have replaced the cables with new ones. The brakes are now opening when using their QR, not fully springing open as I have had it in the past. Enough to brake on the road, plus remove the wheels when needed. Home repairs by Mister Good Enough™. Thanks for the help all!

  • 1
    If you release the pinch bolt holding the inner cable to the brake caliper, do they open fully?
    – Criggie
    Commented Jul 12, 2021 at 12:25
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    When in doubt, always replace the cables. Housings too if they are old or look or feel suspicious.
    – ojs
    Commented Jul 12, 2021 at 19:33
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    Both?? Independent brakes suffered the same change at the same time? OK its looking like something you've done, probably by accident. Can you please add photos of your real bike, of the brake caliper and the brake lever ? Use edit to add to the question
    – Criggie
    Commented Jul 13, 2021 at 11:08
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    @Learningisamess: WD40 is not a lube, don't try to use it as such. Commented Jul 13, 2021 at 19:58
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    @whatsisname I actually used MO94 which I think is a bit more lubricant than WD40. Is it not enough? Should I use a chain lube instead? Commented Jul 13, 2021 at 20:08

1 Answer 1


How to open Tektro calipers:

enter image description here

The little 'nose' locks the release in the closed position against accidental opening.

  • Thanks for the input. I do know how to open the brake QR release, have done it in the past for removing the wheels or replacing the pads. My problem here is to do with the brake cables actually, they seem to not allow the brakes to open anymore. I have decided for replacing them in the next few days. Will report. Commented Jul 14, 2021 at 23:59
  • I edited my question to say that I have changed the cables which has allowed both brakes to open when the QR is used. After a couple of rides with working brakes, I am now facing a new issue: the rear brake QR cannot be closed. When I close it, it opens immediately, the hook of like the plastic piece you call nose cannot hold the metal moving part in place. I am not sure if this means the brake is toast. Commented Jul 23, 2021 at 18:10

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