I just purchased a Yuba Spicy Curry Bosch cargo bike with disk brakes and quick release skewers on both wheels. I haven't had any issues with it so far, in fact, I love riding it, but I have read that using disc brakes with a quick release axle can be dangerous, as the braking force can cause the quick release to loosen and the wheel to fall out. It seems crazy to me. Nobody wants to lose their front wheel riding.

Is the risk overstated? Is it something that only happens with badly designed or improperly adjusted QR/disc setups? I check brakes and tire pressure before every time riding, if I just check the QR as well am I going to be fine?

Would it be safer to just replace the quick release on this particular bike with regular nuts?

I just can't imagine it is a common occurrence, but since I ride this bike with my kid as passenger and share it with my wife, I really don't want to leave it to chance. I am curious to hear from anyone familiar with this particular problem of disc brakes, beyond what is stated in the Sheldon Brown article. Thanks!

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    The skewers are actually the thing you should be checking youtube.com/watch?v=qjOfPzWB2_U Not sure if discs can do anything to them though. I thing it is mainly just annoying to have not the disc brakes aligned perfectly due to imperfect skewer alignment or due to not enough stiffness. Commented Sep 12, 2019 at 16:59
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    If the QRs are closed in the correct and intended way, they are as secure as through-axles. Just teach yourself to do it properly. youtube.com/watch?v=Hcq-PwYj3TE
    – Carel
    Commented Sep 12, 2019 at 17:51
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    Don't take it the wrong way, but Sheldon Brown's information is starting to get a bit stale. There are updates being done there, but technology is moving on and some things are just out of date. There's a heap of useful info still, but its not the authoritative bible it used to be.
    – Criggie
    Commented Nov 8, 2019 at 20:30

4 Answers 4


Most of the time, a bike wheel spins around the axle. When braking, the axle suddenly wants to spin around the point where the brake caliper is grabbing.

The traditional orientation for a fork dropout, with the opening a little forward of straight down, is such that on a rim brake, these forces pull the axle stubs up into the dropout, and no movement can occur.

On a disc QR fork, this orientation of the opening is a poor choice because the axle stubs want to move in that direction under braking forces. Shifting, or in the worst cases ejection, of the hub can occur. A fairly large number of QR disc brake forks have unfortunately been made that use this orientation. That's a trend that's been changing for a while now, but unfortunately slowly. It is the reason a number of QR disc forks have more forward-oriented openings, which looks funny but eliminates the problem.

Skewers that apply higher amounts of clamping force, such as good quality internal-cam ones like Shimano, counteract this tendency but will not necessarily eliminate it.

Usually lawyer lips are sufficient to make actually losing the wheel impossible, but will still tend to allow the hub to shift if the dropout opening gives it a path to do so.


The real problem with quick release skewers on a disc brake bike is that all skewers are not created equally, and some cheaper skewers distributed on QR disc brake bikes were not up for the task (hence recalls).

If you are using rim brakes basically any functional skewer will work, however as pointed out in the linked posts skewers on a disk brake front wheels will experience additional forces associated with braking being applied at the hub, rather than out at the rim (where you have much more favourable leverages and therefore less force required).

If you have a cheap skewer that does not produce sufficient clamping force, then you can get issues. For example, under heavy braking the quick release skewer and wheel may shift in the front drop out. This is usually pretty noticeable (i.e., sudden rotor rubbing or the wheel no longer sitting centered) and could potentially lead to loosening of the skewer over time if material begins to be rubbed away with a back and forth shifting.

This is however easy to test for. Set the front wheel QR as you typically do, take some measurements (visually is often all you need) so you can assess whether any movement occurs, then go for a short ride and try some aggressive stops with the front brake (make sure you know the body positioning for aggressive stops). If your front wheel shifts, then the skewer is supplying an insufficient clamping force for the braking application.

When in doubt internal cam skewers such as Shimano skewers tend to produce the most clamping forces. Whenever I have had issues with a front wheel shifting in the drop out of a QR disc bike, switching to a high quality Shimano Skewer has solved it.

Of course, the industry now provides thru-axle as another mounting option which eliminates this potential issue by directly bolting the axle to the frame. But Quick release can still be used safely given that you take the necessary steps to ensure you have a skewer that can produce the required clamping forces for your braking application.

  • I'd emphasize that internal cam skewers are better because they will produce more clamping force than external cam for the same amount of force that you apply to the lever. We can't see the QRs equipped on the OP's bike, but chances are that they're external cam ones. Those are more common and frequently cheaper than internal cam ones. That said, Shimano do make good and inexpensive internal cam skewers. Some info here; Sheldon Brown's site uses enclosed vs exposed cam, but internal and external seem the more common term. ncbi.nlm.nih.gov/pubmed/26132680
    – Weiwen Ng
    Commented Sep 12, 2019 at 21:04
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    +1: The lawyer lugs on most forks these days will prevent the wheel coming off even if it does become very loose. Because of this, the risk of the wheel falling off is overstated. If the OP's bike has lawyer lugs, I would not rush out and buy new QR's unless the axle is moving. (Done up properly this this highly unlikely, even with cheap external cam skewers.)
    – mattnz
    Commented Sep 12, 2019 at 22:03
  • I think they are external cam judging by photos of different quick release. They seem fine, though the rear is harder to keep an eye on. They have large rotors, which if I understand correctly helps to reduce the downward force. It pays to pay attention to ones bike in any case! Thanks for the facts and insights.
    – SamA
    Commented Sep 12, 2019 at 23:54
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    @Carel: If the brake caliper is mounted inside the seat/chainstay triangle it should actually push the rear wheel upwards during braking (and the caliper downwards). In any case braking forces on the rear wheel are usually much smaller than on the front wheel.
    – Michael
    Commented Sep 13, 2019 at 8:05
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    @ojs I had a crappy Bontranger QR open on a rough trail while riding my late 2000's mtb (hydraulic disc brakes). The retention lips did their thing and I was able to stop. The wheel was obviously wiggly, but it was not ejected. As I wrote in another answer you would have to open the QR, then unscrew it, then ride and brake to eject the wheel. Similarly if you did not properly tighten a thru-axle, it could start to back completely out causing some serious issues (e.g., broken dropout). There is no way to safeguard against foolish behaviour.
    – Rider_X
    Commented Nov 8, 2019 at 23:41

I ended up in a bad crash due to front wheel coming off during the ride. It all happened so fast without warning, there was no time to react or even understand why I fell.

Initially though I was clueless why the wheel came off, but once I researched the link between a disk and QR on the front wheel it is now clear to me what transpired.

I was lucky to not have ended up with broken bones, just concussions and bruises which kept me out of action for full 3-4 days.

YES there is a risk of a disk brake loosening a QR causing a wheel to come off. In my case my ride was a hybrid with disk brakes (Montra Helicon D - from TI cycles), but this can happen with any bike which has disk brakes with QR.

Take a look at the below picture of my setup (image courtesy Amazon listing)

enter image description here

Does it cover all the bad engineering in one shot?

  1. Dropouts pointing downwards in the direction of the rotation of the wheel - a free fall off in case of loose QR latch.
  2. A loosened QR would yank the wheel off the drop out in case of hard emergency braking
  3. QR and the disks on the same side. In theory if the latch gets into the rotor, it would be catastrophic.
  4. No secondary fail safe mechanism to prevent a wheel from coming off.

Now that we examined why the design is lame, here is a little bit of physics and mechanics that will play its part in the rider crashing. (The below is how a friend explained me and he is a Trans-Am finisher, so his opinion is worth weight in gold)

In theory, it goes like this:

A bike's wheel rolls around its axle, because rolling resistance (on the axle and on the tire-road contact) is so small when compared to the sliding friction at the tire-road contact.

What happens when we apply brake?

Braking works because of three forces: pad-rotor contact point (or pad-rim in case of non-disc). Note: pad is fixed to the fork. axle-dropout fastened by a QR. tire-road contact point (a strong sliding force) All the three contact points are on the wheel one way or other.

An effective braking requires that all the three contact points can withstand the forces. In the worst case, the tire-road contact SHOULD be the first to give up and cause a skid. Second worse case is for the pad-rotor to give up and slip the braking.

What happens if the worst case scenario turns out to be a give-up in the axle-dropout contact point? Or why would this even be the case in the first place?

When the pad-rotor contact point is fixed and tire-road grip is strong, there is a massive force at the axle-dropout contact point, with the axle pushing backward. Try to imagine without the dropout on the fork. The wheel will try to rotate around the pad-rotor contact point. If the rider+bike has sufficient momentum (speed), this can cause enough force for the wheel to rotate around the pad, specially if the dropout is somewhat on the circumference of the circle drawn with the axle around the pad and in the direction of rotation of the wheel. If the dropout directly is completely opposite of the direction of rotation of this circle of axle around the pad, then the only way the axle can come out of the dropout is to break/damage the dropout. Montra Helicon D front fork disk brake and skewer design fault It so happens that a Montra helicon dropout can easily cause the axle to come out. Apparently, there were so many recalls in the US on this faulty design of the dropout. I compared this bike with my KHS 650B. There is literally no room for the wheel to come out in case of KHS 650B (you can google for images of both).

You should check if your fork dropout is designed safe enough. I WILL RATE THIS A VERY HIGH RISK CATEGORY FAULT.

  • I've tweaked this a little to bring out the actual answer in your reply. Sorry to hear about your accident. The fix is to add QR checks to your monthly maintenance routine, so that loose ones will be noticed and remedied, and to identify how tight is right.
    – Criggie
    Commented Dec 18, 2019 at 19:40
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    @Criggie ya, I am now smarter and I guess will never be able to fully trust the QR latches after the incident. Commented Dec 19, 2019 at 5:41
  • Thanks for the edits Ashwin. That made the answer much better! You might also add the QR skewer is pretty rubbish. Such skewers often are stiff to close but do not provide a lot of clamping force. Still, decent engineering should not let it get to the point where it depends on skewer quality alone. — ps: I hope you recovered completely from your concussion and there are no lingering long term effects.
    – gschenk
    Commented Dec 19, 2019 at 14:37

There was a huge recall of quick release bikes from Trek in 2015 (about 1000000 units in US and Canada). The reason was that the lever could, according open far enough to catch in a disk brake rotor. That could lead and in several cases did lead to serious injuries.

This particular means of failure ca be mitigated by having the lever on the drive side (opposite to the disc).

Loosening of a quick release by disc brakes is described by James Annan. I quote:

There are two main aspects to the failure.

The disk brake generates a massive force largely downwards in the direction of the open fork ends. The friction of a quick release skewer is often not sufficient to stop the axle slipping down in the dropout slot. This is explained in more detail here,

The QR is initially restrained by the retention lip on the fork (assuming it is present), however over time the slipping of the quick release leads it to unscrew, which is described here. Once it has unscrewed enough, it can be forced over the retention lip and the rider will crash.

Modern disc brake bikes tend to be sold with thru axles instead of quick releases.

  • Sheldon Brown passed away in 2008, how did he comment on a 2015 Trek recall?
    – lanzz
    Commented Sep 12, 2019 at 20:37
  • @Ianzz The maintainers of the site did. But if you mind that source as untrustful, I can replace it... Commented Sep 12, 2019 at 22:14
  • It makes sense that bikes with disc brakes would also be thru axle rather than dropout. It further complicate things, but if you already chose to complicate things with hydraulic disc, why not accept that for safety sake?
    – SamA
    Commented Sep 12, 2019 at 23:57
  • @SamArcher Firstly, there are also mechanical disc brakes. Secondly, there is nothing complicated about a thru axle. It is a very simple thing, it has fewer part than a quick-release. Just a screw and a nut. Commented Nov 8, 2019 at 12:29

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