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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:

rear

front

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!

Learning is a mess
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    If you release the pinch bolt holding the inner cable to the brake caliper, do they open fully? – Criggie Jul 12 '21 at 12:25
  • @Criggie Yes they do fully open. – Learning is a mess Jul 12 '21 at 12:29
  • The cable isn't sliding smoothly. – Daniel R Hicks Jul 12 '21 at 12:47
  • Should the cable be replaced? I questioned the cable, but since the release broke down suddenly I crossed it off. – Learning is a mess Jul 12 '21 at 13:21
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    When in doubt, always replace the cables. Housings too if they are old or look or feel suspicious. – ojs Jul 12 '21 at 19:33
  • Front or rear brake? Or same behavior on both? It’s unusual for the front brake cable to have excessive friction unless it’s damaged or very old. If you don’t want to bother with cable+housing replacement: Lube can improve things for a short time. – Michael Jul 13 '21 at 06:32
  • @michael Both, and it happened simultaneously on brakes that are 6 years old. I have tried lubing the cable with WD40 which did not solve the issue. – Learning is a mess Jul 13 '21 at 09:46
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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 Jul 13 '21 at 11:08
  • If the levers are Tektro as well, they have a release pin at the top of the lever! – Carel Jul 13 '21 at 11:49
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    @Learningisamess: WD40 is not a lube, don't try to use it as such. – whatsisname Jul 13 '21 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? – Learning is a mess Jul 13 '21 at 20:08
  • I have added pictures. You can see that the brakes have a bending point, I think a replacement is mandatory here. – Learning is a mess Jul 13 '21 at 21:09
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    @whatsisname WD40 Most definitely IS a lubricant. Alas, what else would it be? It is a water displacing substance containing various lubricants. It may be not the most durable one, but it certainly is a lubricant. Sauing that WD means "water displacement" so it cannot be a lubricant is an utter nonsense. – Vladimir F Героям слава Jul 14 '21 at 19:22
  • @VladimirF: it doesn't matter what it's called, just what it is. And it isn't a lubricant, it is fundamentally a solvent blend that happens to have some of its components having some lubricating properties. However, those 'lubricants' are basically light volatile mineral oils, that will before long completely evaporate leaving the base metal completely unlubed, and unprotected, and will quickly corrode. Saying WD40 isn't a lube is the same as saying squares don't work for wheels. Sure, you could make a square wheel to prove a point, but that's not going to work practically. – whatsisname Jul 15 '21 at 00:45
  • So in short, if you want to lubricate something, use a substance designed for that specific purpose, don't use something that happens to kinda sorta have some of the similar properties by complete coincidence but with a huge marketing budget, unless you are absolutely desperate for options. – whatsisname Jul 15 '21 at 00:46
  • @whatsisname OMG The solvent is a carrier, used to carry the active substances that are delivered in the solution. Most of the active substances are various lubricants. It is not a grease but it is a lubricant and it is perfectly fine to try to use it to unstuck stuck parts such as cables. If you buy a paint spray, it is also mostly a solvent, but you won't say it isn't a paint but a solvent. Also, I haven't ever seen a WD40 advert. It is just a thing that most people happen to have at home. There is no reason not to try it to unstuck some cable. – Vladimir F Героям слава Jul 15 '21 at 06:20

1 Answers1

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How to open Tektro calipers:

enter image description here

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

Carel
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  • 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. – Learning is a mess Jul 14 '21 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. – Learning is a mess Jul 23 '21 at 18:10