Yes.
Around the time Russ had his accident, we had similar.

A friend of mine had RS Psylo for/Hope QR/Shimano hub. He was 18+stone, 203 rotor on Hope 4-pot brakes, travelling at spinning out speed – so 30mph(+/-) – on a hill track.

The front wheel came out the dropouts at high speed, braking hard moment.

The wheel came out so fast that the fork legs hit floor, and his (new) gloves had damage to the knuckles, where he was still holding the bars. The dropouts/bottom of forks was ground away by impact(s) and so we could not conclusively see what had happened fully – one dropout partially remained, and the ‘tab’ that held the wheel in was missing – and was ‘sheared’ not ‘ground’, but again, no reliable conclusions could be gained.

Cue serious injury, halfway up Helvellyn, miracles and co-incidences and an amazing rescue and hospital. I was told on the hillside he would not live.

He woke up a fortnight later. 6 months in rehab unit for brain injury. 10 months until back in his home alone. 16 months from accident ran London Marathon for the Glenridding MRT. He still bears the physical scars and memory issues, but its 95% back to how he was.

I have had no issues with shimano QRs in ~25 years of using them, other brands may differ in weight and operation but shimano are about the best for staying closed IME…

I can still see some further “standardisation” on the horizon for disc braked CX/Gravel/Road bikes/forks, 15mm vs QR (vs something else?) and Flat vs Post mount… They’re going to piss us a about a bit more yet, it’s almost certain.

Having jumped on the bandwagon with a QR/PM frameset, I can’t help thinking I might have adopted a tad too early…
But it works and I am not yet dead from QR-disc brake related wheel ejection.

Hmmm, that is a grim tale.
I reckon I’ll run 140mm rotors with a DT Swiss skewer and won’t be tipping the scales beyond 13 stones, still your story is so sickening that it’s making me think…

It has made me super careful about QR’s being done up tight, and being checked mid ride.

I only use Shimano QR up front. It also made me only buy bolt through since then for myself, being a big lad.

Note also that the older Psylo’s – like so many older forks – had minimal retention tabs compared to newer forks. We do also have to wonder that as such a big lad, had he damaged the forks before? Was it done up that day or come loose (we were a long way down the descent)?

On the brightside, we all made BBC’s ‘999’ programme and raised a metric sh*t load of cash for MRT.

Someone the other day mentioned closing the skewer over the caliper, and altering the closure angle by adjusting the locknut.
Both of which tell me that even on here people don’t understand how QRs work.

That was me, your statement puts you in the camp your lumping me into.

Russ Pinder isn’t the only out of court settlement that I know of. The problem was worse back in the days of boutique hubs and skewers with little or no knurling, forks with no retention lips, and dropout angles parallel to fork blade. The gross design error still persists but catastrophic failure is far less common due to a number of minor tweaks. Interesting to hear that despite these, people are still having occasional problems. Bolt-through is such a clearly superior design (when disks are involved) that I’m surprised it hasn’t caught on more widely, even for road bikes.

Wasn’t the problem actually vertical dropouts? Any axle can be loose (whether or not it works loose or was simply insufficiently tightened in the first place). As I understand it, a loose axle will try and trace a circular path around the calliper when the brake is applied; with a calliper behind the hub the axle could move through the open part of the dropout.

I thought that forward facing dropouts were meant to solve the problem as the same axle tracing the same path in a forward facing dropout would simply be driven hard against a solid part of the dropout (I could be wrong though!).

Hardly, i can work a QR, not only that, i understand how they work.

Over the caliper indicates that the lever is sticking out, over the caliper, i.e. hasn’t gone over cam, so it’s not closed properly.
Unless you mean over the caliper in the sense of above and in plane.

Altering the closure angle by tightening or loosening the nut puts the skewer in the same position, the lever not going over cam. even though it’s the same load going through the lever. (Given that it’s set up properly in the first place.) The closure angle is a given. At least 90 degrees.

The orientation of the skewer, to clear bits of frame/fork/caliper doesn’t need the nut adjusting.

matt_outandabout – Member
Yes.
Around the time Russ had his accident, we had similar.

A friend of mine had RS Psylo for/Hope QR/Shimano hub. He was 18+stone, 203 rotor on Hope 4-pot brakes, travelling at spinning out speed – so 30mph(+/-) – on a hill track.

The front wheel came out the dropouts at high speed, braking hard moment.

The wheel came out so fast that the fork legs hit floor, and his (new) gloves had damage to the knuckles, where he was still holding the bars. The dropouts/bottom of forks was ground away by impact(s) and so we could not conclusively see what had happened fully – one dropout partially remained, and the ‘tab’ that held the wheel in was missing – and was ‘sheared’ not ‘ground’, but again, no reliable conclusions could be gained.

Cue serious injury, halfway up Helvellyn, miracles and co-incidences and an amazing rescue and hospital. I was told on the hillside he would not live.

He woke up a fortnight later. 6 months in rehab unit for brain injury. 10 months until back in his home alone. 16 months from accident ran London Marathon for the Glenridding MRT. He still bears the physical scars and memory issues, but its 95% back to how he was.

😯 crikey, that sounds hellish.

I’m pretty sure it was either Rock Shox or Manitou who said not to use larger than 160mm, or maybe a 180mm rotor with their QR forks. Don’t think this was right away though, probably after an event like the above.

I’ve personally never had a problem, but I’ve never used anything other than internal cam skewers. I remember a mates rear Hope QR once came undone; not really an issue on the rear though.

Altering the closure angle by tightening or loosening the nut puts the skewer in the same position, the lever not going over cam. even though it’s the same load going through the lever. (Given that it’s set up properly in the first place.) The closure angle is a given. At least 90 degrees.

I think what was meant by “closure angle” is the angle between the ground and lever, while looking side on at the bike. I certainly hope it doesn’t mean the angle between axle and lever as like you say, that should always be past 90 degrees (or always less than, depending on how you’re measuring).

But you don’t need to adjust the nut for that. you just rotate the entire QR around it’s axis.

OP: Yes. But nowadays QR dropouts are designed slightly better, for example with the “lawyer tab”(?) – basically you have to loosen the QR significantly further to actually get the wheel out of the dropout

I’m pretty sure it was either Rock Shox or Manitou who said not to use larger than 160mm, or maybe a 180mm rotor with their QR forks. Don’t think this was right away though, probably after an event like the above.

That’s not the reason for the max limit on rotor size – larger rotors are actually better because it’s the ratio of wheel size to rotor size that’s the issue. Braking at the same speed, a 29er with 140mm rotors puts quite a bit more force through the axle etc than a 26″ with 205mm rotors.

The size limit is, as far as I can work out, more about the type of customer who would fit big rotors.

The fundamental problem is that both dropouts and quick releases were invented decades before the disc brake, and when discs came along no-one properly considered that the QR was now not just to stop the wheel falling out, it was taking 4x as much force from the brake.

The only time I’ve had problems with qr loosening was on a rim braked bike – the problem was the crappy qrs (Kore) . Changed the qrs – never had problem since even on disc braked bikes as long as you do them up tight enough.

I’ve had a rear road disc wheel partially pop out of the dropout on the brake side. May have been my fault for not tightening the QR enough. Or maybe I did – I don’t know. Not had a problem on the front but I have seen my steel fork twist under high speed braking and cornering (40mph+ descents over 20km) and that was alarming. Given the choice today I’d always go for a thru-bolt now.

There was a big debate about this some years ago (just looked it up, 2003!) largely driven by James Annan, who had an accident and published a website arguing it was caused by using discs with QRs and conventional dropouts.
This argument rumbled on for quite a few years. Given that the use of discs and QRs must have become much more common since then, I’m not aware that we’ve seen any evidence that it is a genuine problem.

My anecdotal evidence is that I’ve been using discs and QRs for 16+ years on and off road, including 13 years of commuting 5 days a week, and I’ve never seen a QR work loose. I’ve always used old style enclosed cam Shimano or Mavic QRs, and I suspect a lot of the lightweight alternative QR designs are a bit suspect. I remember someone on here explaining how he had solved the problem of his loose QRs by clamping them shut and then rotating the closed lever 90 degrees to lock them tight….!

My work was prompted by Annan – since then, through axles have become much more common, so that’s why the number of incidents is low I think.

Well, I’ve just gone and done it. I’ve been staring at this frameset for months and the recent serious illness of a couple of near and dear ones has convinced me that life’s too short not to.

I paid 100 Euros extra to upgrade to a thru axle fork. Didn’t want to have it going through my mind on some of my more extreme cross outings.

I suspect a lot of the lightweight alternative QR designs are a bit suspect not fit for purpose.

FIFY

Since the original Campag design was enclosed, fair play to the guy for getting it right from the off.

since then, through axles have become much more common, so that’s why the number of incidents is low I think.

I’m not so sure about this, plenty of XC, CX, Road and lower end mtbs still come with discs and QR’s. I think if there was a major issue it would have been noted by now. Key thing to note is most bike brands use ‘proper’ QR’s designs from Shimano, Mavic, Sram etc. not the lightweight after market items that I suspect are the main culprits.

The fundamental problem is that both dropouts and quick releases were invented decades before the disc brake, and when discs came along no-one properly considered that the QR was now not just to stop the wheel falling out, it was taking 4x as much force from the brake

Well yes, except that on a horizontal dropout they may be taking pretty significant loads from the chain. My first changeout of external cam for Shimano was due to an SS with horizontal dropouts creaking due to pedalling loads (it worked). Wasn’t the QR invented due to the need to swap between fixed and freewheel quickly during a race with cold/tired hands?

Edit – of course the consequences of popping the front wheel out are more severe than pulling the rear out of place.

If QR is so bad its amazing the wheels stay on the pro roadies bikes when there doing 70mph down mountain passes, putting several hundred watts or more power through the wheels in the sprints and especially when the mechanics chuck the wheels in within seconds after a puncture,
Really there should be wheels flying off right, left and centre.

unvolo – do those same roadies use discs? 😉

I had many customers at freeborn Esher buying lightweight qr skewers and putting their steel shimano back on pronto. Dirt jump, DH, FR all best on through axle or steel skewers.

If you ride hard or are heavy you can put a huge load into the axle interface with disc brakes? Old articles mentioned 400nm+ peak load.

For QR, Shimano, Campag, or DT Swiss RTS work well but make sure to clean/oil the cam and skewer shaft from time to time.

I had a hydro disc brake road bike last year. The bike had 45 degree forward/down fork dropout to help counter twisting force.

I rode that bike very hard 60mph+ DH runs, , front wheel secure but rotor tinkling on climbs or sprints, and rear wheel tendency to unseat ever slightly under repeated hard braking. Creaking under power, had to stop, open the QR, wiggle wheel to reseat and retightented. Often…tried shimano, DT Swiss RTS no difference.

Bike got sold off, got 7kg caliper race bike with Shimano dura ace skewers. Lovely….

2017 model of my disc brake bike has 12mm through axle DT Swiss front and rear. Fantastic!!

This happened to a friend of a friend, wheel came out on a non technical fast descent. I don’t know the full technical details but the case was settled with the fork manufacturers just before the case was due in court. The rider had serious back injuries and I think he was lucky to walk again.

The fundamental problem is that both dropouts and quick releases were invented decades before the disc brake, and when discs came along no-one properly considered that the QR was now not just to stop the wheel falling out, it was taking 4x as much force from the brake

I think there were two slip ups when disk brakes were introduced:

]Mounting disk brakes on the back of the forks creates a large force pushing the wheel out of the dropout. Why not mount it on the front of the forks so the force is pushing the wheel into the dropout?

To run disks people needed to switch their hubs and frame/fork to be disk compatible anyway so the opportunity should have been taken at that time to switch to a stiffer and more secure wheel clamping system – esp. as it was obvious that putting the caliper on the back of the fork creates a force pushing the wheel out of the dropout

The road/CX bikes with QR and disks on the rear of the fork do concern me a bit as it is possible to generate huge braking forces when running sticky slicks on a grippy road.

Note that in terms of the amount of force created pushing the axle downwards and out of the dropout. This piston position:

is not as bad as this piston position:

That’s not the reason for the max limit on rotor size – larger rotors are actually better because it’s the ratio of wheel size to rotor size that’s the issue. Braking at the same speed, a 29er with 140mm rotors puts quite a bit more force through the axle etc than a 26″ with 205mm rotors.

I do not agree. If same braking force (at the tyre) is done then force on the axle will pretty much the same no matter what the rotor size is, although the position of the force may vary if the different rotor size also means moving the pistons angular position on the disk as per above illustration.

If one does the kind of worst case assumption that these max sizes are based on e.g. at high speed the piston clamps the rotor with a certain maximum force then the larger rotor will create a larger force at the axle than the smaller rotor for two reasons 1)larger distance between piston and axle creates a larger lever 2)at the same angular velocity a larger rotor has greater displacement past the piston, meaning more braking force generated when clamped with the same force.

Edit:Sorry the formatting of this appears to be a bit broken tried a few things but I cannot fix it – looks fine in the preview.

Why not mount it on the front of the forks so the force is pushing the wheel into the dropout?

I’ve done that a few times on tandems. People have commented that the caliper bolts might snap, but that shows a misunderstanding of the IS mount at least (post mount, they might have had a point).

If same braking force (at the tyre) is done then force on the axle will pretty much the same no matter what the rotor size is

Not the case, there are two components to the force on the axle. There’s the reaction force to the braking momentum, which acts directly backwards and is indeed independent of the braking system. But we’re not concerned about that force, we’re concerned about the ejection force acting downwards(ish) caused by the caliper. That force is proportional to the ratio between the wheel size and the rotor size – a larger rotor means a lower force. The ultimate example of this, of course, is a rim brake where the ratio is near 1:1 and there’s no significant ejection force.

Not the case, there are two components to the force on the axle. There’s the reaction force to the braking momentum, which acts directly backwards and is indeed independent of the braking system. But we’re not concerned about that force, we’re concerned about the ejection force acting downwards(ish) caused by the caliper. That force is proportional to the ratio between the wheel size and the rotor size – a larger rotor means a lower force. The ultimate example of this, of course, is a rim brake where the ratio is near 1:1 and there’s no significant ejection force.

I don’t see it this way, I see the ejection force as being the force acting on the rim/rotor fulcrumming through the structure of the wheel and acting on the axle.
Larger rotor means a lower piston force to achieve a certain amount of braking effort (this is not the worst case situation I described), but is then magnified by a longer fulcrum so results in an equal force on the axle.
The vector of the force on the axle is 180.deg or pi.rad of the vector of the force on the rotor/rim for rim brakes the force is pretty much horizontal hence little downward ejection force.

Yes.

Although it did take one hell of a sideways landing and crash to get there.

This was a few days after that video of Cedric Gracia rupturing his femoral artery, so when I picked myself up and found the wet sticky patch growing from my crotch/hip I panicked! Thankfully it was just a burst gel in my pocket!

“

but is then magnified by a longer fulcrum so results in an equal force on the axle

“

You’ve got that backwards. The longer fulcrum means less force.

Imagine a pole, with one end on the ground – that end is the caliper.
Imagine lifting the end of the pole with a certain force – that end is the tyre on the ground, and the lifting force is the braking reaction force.
Now imagine using this pole to lift something heavy, like a workbench. The farther the lifting point is from the ground, the less force you have.

The fulcrum is a fixed point. The braking reaction force is the same (you’re slowing down at the same speed). What changes is the distance from the pivot to the load, and the greater that distance the less the force.

It’s also true that the angles are different for rim brakes, but that doesn’t alter the basic fact that the smaller rotor means a larger ejection force.

PS, stop underlining everything, you’ve borked the quotes system 😉

I had one of those Syncros QRs fall apart – the head was threaded on with a tiny spot weld(?) keeping it from coming unscrewed.

No braking involved, just a low speed heave and twist on the bars and it shot off into the bushes…

I’ve used Shimano QRs ever since.

I read a bit of this thread a few days back and have to admit I largely put it down to user error. Came down Ditchling Beacon on my Defy on the way home from work today, car in front held me up so was on the brakes the whole way down. Brake pads were tinging on the rotor at the bottom and found both QRs were coming loose….About to buy some Shimanos to replace the OEM Giants. Next bike will have thru axles.

Has anyone had any experience of the DT Swiss RWS skewers? I’ve not had a problem with my current skewers except that I end up doing them up so tight that they’re a pain to undo so wonder if they’re worth a try.

You’ve got that backwards. The longer fulcrum means less force.
…
The braking reaction force is the same (you’re slowing down at the same speed). What changes is the distance from the pivot to the load, and the greater that distance the less the force.

It’s also true that the angles are different for rim brakes, but that doesn’t alter the basic fact that the smaller rotor means a larger ejection force.

Gotcha, I stand corrected and see now that smaller rotor means more ejection force, also a larger distance between tyre contact patch and the piston means more ejection force – and that often decreasing rotor size increases tyre contact patch to piston distance so creates a double whammy effect.

However, a larger disk also means less piston clamping force for a given braking force, and what I can’t get my head around is if this makes the piston more or less of a pivot point that creates axle ejection forces. I mean, it isn’t an actual pivot (unless the front wheel is skidding, sort of) because the rotor is always moving through the piston, but a kinematic one created by the friction between the pad and rotor.

PS, stop underlining everything, you’ve borked the quotes system 😉

I was underlining stuff because the quotes were borked 🙂 I don’t know how my earlier post borked it, I tried smaller images and that didn’t fix it.

test quote

Twisty, you have to squeeze the brakes harder for a smaller rotor to get the same braking effect (for a given calliper/lever design).

However, a larger disk also means less piston clamping force for a given braking force, and what I can’t get my head around is if this makes the piston more or less of a pivot point that creates axle ejection forces.

Less. Don’t worry about the rotor actually moving through the caliper, what matters is the resulting force on the caliper, and the equal and opposite force on the axle.

The piston clamping force doesn’t have a direct relationship here, it depends on whether it’s a 2- or 4-piston caliper, the pad size and material, etc. All that matters is that it applies a certain braking force to the rotor, and that force is proportional to the ratio between rotor diameter and wheel diameter, for a given rate of deceleration.

Don’t worry about the rotor actually moving through the caliper

But,but because the rotor is rotating under the pad doesn’t that create a shear force which also acts on the axle.

<sigh>Sometimes I almost wonder if I should have studied mechanical rather than electrical engineering 🙂

No need to respond, I think I’ve learnt enough about this for now.
The important thing is that large diameter disks are good which is comforting because: I like big disks and I can not lie.

Has anyone had any experience of the DT Swiss RWS skewers

Scary bloody things they are. Work themselves loose if you don’t check them every ride (this is my experience of them anyway) – Shimano are best, no doubt.

In answer to OP – no, never.

Conversely, I once did a day’s riding at Gwydrr Forest on my old hardtail equipped with Marz forks with their QR20 system, which had a 20mm bolt thru QR with ‘tabs’ that screwed in on the bottom to enclose the axle. This wasn’t the newer version, but the original where the tabs had to be fixed on with a 4mm bolt. Bike had a Hope 4-pot with 6″ rotor.

Did the whole day without having fitted the tabs so effectively only having half the clamping force. That was scary when I came to take the front wheel off afterwards! 😯

Few years back my wheel came out of a Kona Project 2 rigid fork, the QR was a Shimano one IIRC and had been done up tight.

Luckily for me it fell out as I stopped to take a breather at the top of a climb rather than during the descent I was just about to start… 😯