gsa103

The pros frequently use the same skewers we do. If you watch Tony Martin's flat in the TdF this year, the announcers commented that he immediately started loosening the QR so that it would be ready for the mechanic.

The funny part with disc brakes is that many disc forks are actually significantly MORE difficult to remove with QRs than through axles. I rode a bike with a low end RockShox fork, and the QR sat in a concave dimple to provide better wheel location. To remove the wheel, the QR had to un-screwed until only a few threads were engaged, effectively making it a through axle. Modern disc brake QR's tend to combine the worst aspects of QRs and through axles, with the benefits of neither.

tarwheel 

I file the tabs off my bike forks ... eventually. I still haven't gotten around to doing it on my latest acquisition, a Soma Saga touring bike I bought last fall. It takes a while, even with a Dremel tool.

Even though I detest the tabs, I have no doubt that they prevent a certain number of accidents. I am continually amazed at the number of people I see riding without any apparent basic knowledge about cycling -- eg, how to fix a flat, setting the correct saddle height, wearing helmets backwards, etc.

Andrew R Stewart 

No. The recall is because when people don't use the QR properly and it releases during riding the lever can swing back beyond 180* and engage the rotor. Big difference being the opposite of what was said above. Andy.

WizardOfBoz

I just like elegant, convenient, functional design that derives from the requirements of riding. It seems to me that a lot of things are put in place,. such as forcing ugly and less-functional polypro cutting boards to replace maple, or cpsc reflectors that don't protect much of anyone and were forced on us by an evil cabal of corporate lawyers, suits, and regulators.

It's not something that keeps me up at night. It's just annoying.

Gresp15C

I suspect that lawyer lips were the brainchild of engineers, not lawyers.

When designing a mainstream product, engineers will get together and review a design for risks. One common technique is "failure mode and effects analysis." Based on typical experience (I am involved in product design), the reviewers will pay particularly close attention to anything that's supposed to be handled or adjusted by the consumer. Something that the consumer is supposed to adjust, that could kill them if they get it wrong, would be a screaming red flag, and the designers would be sent back to the drawing board.

But shouldn't the consumer know what they're doing? Sure, but a mistake made by an ignorant consumer still represents an elevated level of risk.

Now, I'm not claiming that the engineers got this right, but only trying to give a glimpse of the thought process that might have been involved.

I think the problem lies in the desire to market one-size-fits-all products. In a perfect world, you'd have a choice of nutted or QR axles, and the dealer would apprise you of the tradeoffs. I'd choose nutted axles, because I have no practical use for QR. In fact, nutted axles plus lawyer lips would give me an added measure of security.

dabac

Depends on the overall design. If you make the "hand" end of the lever proportionally longer, the clamping force remains the same.

dabac

Cotic actually did that, for awhile, some years ago.

As to why it's not done on a wider scale, I think there are several influences coinciding here:
1) Wheel ejection is a rare enough occurrence, needing a chain of events to happen.
Probably along the lines of below-average-q/r + above-average-brake force + on/below average closing force + something about ride length/time since last install. Possibly something about the mating surfaces between fork dropouts axle locknuts and lever/acorn too.
Change any of the above and the event doesn't happen.
2) Moving the caliper now, would be admitting having been in the wrong for several years. If it was me, I'd worry about exposure to lawsuits.
3) There are other benefits from moving to thru-axle designs - in short, they help stiffen up the fork - and then you get rid of the wheel ejection problem at the same time. And by claiming "stiffer fork" as the reason for the design change, they dodge the responsibility bullet.
4) front-mounted calipers look really funky, like a flag flying into the wind. If a thru-axle or differently aligned dropout slots is enough to remove a fairly rare event, it gets them off the hook easier.

But yeah, I think it's sloppy engineering.

The three rules of safety-oriented design are:
1) Eliminate the dangerous feature.
If that can't be done
2) Enclose the dangerous feature
If that can't be done
3) Educate the user about the dangerous feature.

And the bike industry went about it completely bass-ackwards.
They started with 3) "Keep the quick release well closed". Then went on to 2) , thru-axles, changed dropout slot alignment.
And still aren't considering 1) .

Now, I'd be willing to admit that 2) can probably be made functionally good enough.
But the wheel ejection risk hasn't been removed - the physics are still there. It has merely been handled.
The difference between taking painkillers or finding out what's making you ache.

dabac

Keep in mind that the force that can be generated while braking on a good surface is considerable. In the early days of road-going disc brake bikes there were incidents of bent forks as well as buckled down tubes.
One of the events I witnessed, half the caliper side dropout of a Marzocchi Bomber simply broke off.
Also remember that there's a sneaky unscrewing action going on here. Depending on how much the acorn manage to unscrew, and the exact configuration of the mating surfaces, the fit might get sloppy enough for the acorn/skewer base simply to tilt a little and then slide over the lawyer lip(s).
If there's force enough available to split a dropout, there's probably enough force to stretch a skewer too.

dabac

I'm not too sure on how much added security that would actually bring. Sure, a thicker axle will be less prone to stretch to the point where the nuts can slip past the lawyer lips. But a nutted axle wouldn't be immune to the forces that makes quick-releases unscrew.

Homebrew01

Even if lips prevent wheel ejection, couldn't wheels get forced cockeyed in the dropout, as one end of the axle gets forced down to the lip ?
Unless a careful rider sets the axle against the lip, instead of the usual practice of setting the axle against the inside of the dropout.

dabac

Certainly. Noticing sudden rubbing, or seeing the tire pull to one side while braking can save a rider from the wheel ejection experience.

Trouble is, particularly with "real" mtb riding, you may not have the attention to spare to watch how your tire tracks in the fork very often.

Gresp15C

I'm not a mechanical engineer, but my thought is that on a nutted axle, the two nuts are virtually independent of one another. If one of them works loose, or is forgotten about for some reason, the other one is still there. What I like is the redundancy -- a single mode failure is not a disaster. Even lawyer lips don't protect from breakage of the skewer, but only a particular user error.

But thinking about it, I'm not sure how lawyer lips plus nuts would be an improvement.

intransit1217

Do lawyer lips add to the strength of the dropout thereby reducing the likelyhood of a split dropout?

Homebrew01

No. They are little tabs of extra material at the very tip of the dropout.

dabac

Depends on design. Current suspension forks tends to have a circular recess for the q/r and acorn to seat into. That design does add a bit of material in a place where it does a little good.

mstateglfr 

Huh- cutting boards? Though that has nothing to do with this, I get that you are including it because you are ranting about the good things that have been lost due to the greedy litigious lawyers.
...I bought a tri-wood cutting board a few months ago. Maple was one of the woods. What mass force change are you referring to? Did big plastic's fatcat lawyers lobby for a mass ban of wood cutting boards?

As for reflectors- just remove em. It isn't tough.

fietsbob

Plastic cutting boards, that you sterilize in the dishwasher, are best when cutting raw pork and other meats.

Department of Health won't inspect your Home Kitchen .. they will shut down Commercial Kitchens that are poisoning people.

WizardOfBoz

dabac, Very interesting incident reports. Kind of a a good illustration why it's not a great idea to retrofit disks to a bike frame (and fork) not designed for such stress.

Gresp15c, Used to do FMECA (Failure Mode Effects and Criticality Analysis - the criticality part because this was in the nuclear fuels processing sphere). A blast from my past. You're probably right- we engineers may be complicit in this. To some extent, I am sympathetic to adding engineering overrides that prevent user/pilot error. I guess I just resent the beautiful, simple, elegant and effective QR system on (for example) Campy hubs in a hand-built Colnago or Waterford being morked up with something that completely obviates the function of the QR. Might as well use fixed nuts and not a QR.

Regarding you redundancy argument, you may not be an engineer but your note shows you are thinking like one. Not always a good thing, but in this case it's a compliment!

WizardOfBoz

fietsbob,

That's my point. Wooden cutting boards, properly used, were not poisoning people. The regulators did come in and mandate that maple blocks were illegal and that polypro must be used commercially. Without research. On a theory. I'm trained in science: I like theories. But if you are going to put the full force of government (including the power to imprison people or close businesses and destroy people's livelihoods) behind regulations, shouldn't the theory used to create those regualtions be tested first? Your last sentence underscores the basis for my skepticism: The gubmint shouldn't be shutting places down due to a false theory.

First, an admission: I used the polypro cutting boards at home. I don't have a big maple butcher's block at home. Nothing against those big butcher's blocks, but I can put it in the dishwasher. In fact, I'd love to have one of the big butcher blocks, but I don't have the space and I don't want to lay out the dough (I'd rather set aside those $ for a set of Shimano C35 wheels).

But after the regulation came out, some experts suggest that polypro boards are worse (keeping a higher bacterial load in deep grooves) than maple. Here is a synopsis, from https://news.ncsu.edu/2014/09/cuttin...s-food-safety/

The point is, if you clean and sterilize your butcher block, and let it dry overnight, it's as sterile as the polypro you ran through the dishwasher.

The whole point about cutting boards was an analogy. I am not against well-considered, tested regulations that address a real problem in way that other approaches cannot or have not solved. I am against knee-jerk reactions realized as regulations or laws based upon untested theories that address imaginary problems that could be addressed by less coercive measures. I submit that, as a society, we have swung too far towards the latter.

Lawyer lips or other retaining measures on kids or general population bikes? Fine. In fact (because we have a few data points from other posters) this leads me to believe that those lips are probably useful on a wide variety of bikes.

Insisting that lawyer lips be placed on QR hubs (when the whole point of QR hubs was to allow the wheels to be removed and replaced quickly)? I vote no.

Through-axles may make the issue of retention devices on QR hubs moot, though.

Gresp15C

Well, I'm a physicist, so my job is to provide the failure modes.

I switched to nutted axles on two bikes. Both were old frames without lawyer lips. One had little shoulder washers with nutted axle, so you had to loosen the nuts a fair amount in order for the wheel to fall off. That was on my old Schwinn, so you can see that front wheel ejection failures were on their minds even before they adopted QR's. In other threads, I've referred to the front QR skewer as the Jesus bolt of the bike.

One thing to note is that I already had nutted axles in back, thanks to IGH's, so I already carry a wrench. But I think that if nutted axles were common, an axle nut wrench would just be one of the things in every seat pouch, along with tire levers, patch kit, and an innertube.

fietsbob

the Schwinn solution to have a tab with a hole in it as part of the Axle nut stack on both ends,
which snapped over a screw head inside of the lower fork leg, worked fine for purpose.

WizardOfBoz

fietsbob,
Thanks for that. I wondered how it worked. Your note made me curious. I referred to the font of bicycle wisdom that is the site of the late Sheldon Brown, RIP. It had pictures! Apparently invented by a Schwinn engineer named Frank Brilando. Patent number 4103922, granted in 1978. Article here. A fascinating thing is that Mr. Brilando competed in cycling in the Olympics in 1948 and 1952, if its the same Frank Brilando.


Brilando, the cyclist:

erikz

Someone tried to steal my dynohub front wheel but I had set the brake pads set so close to the rim that it wasnīt possible to reomve the brake pipe. The thief didnīt retighten the QR and I took a bad dive on the concrete. Knocked out three teeth, split my upper lip in shreds and got a small bleeding in my skull. Got some obvious rough looking scars in my face since then. My fork did NOT have lawyer lips. Early ninties Focus Crater lake. Needless to say I now regularly check my QR skewers. Just thought I should share that with you. Oh yeah, broke my nose too.

WizardOfBoz

erikz,

I, too took a trip over the handlebars when I didn't put enough glue on my rim and my sewup rolled off the rim and stuck in the brake. I would still have a lot of antipathy towards that thief, but in my case, it was pilot error. Broke my jaw, cracked 13 teeth, and they had to scrape the road pebbles out of my jaw bone before sewing me up.

A long time ago, but your caution is worth repeating. I was not aware that the reason for the curve in the QR handle was to indicate that the thing was tight...

Glad you recovered and (given that this is a bike forum) are still riding. Is it "Sicher Riesen" or just "Gute Reisen"? Both, I hope!

gsa103

Yes, I had to resort to that practice on my previous disc brake equipped mountain bike. If I seated the wheel in the top of the drop-out it would tilt causing brake rub. This is why RockShox has adopted QR locations which are basically conical, so the the wheel is consistently aligned. The irony is that they require you to pracitally un-screw the QR, negating any advantage over a proper through axle. A few manufacturers have altered the drop-out angle (rotating more forward) to help alleviate the issue. It's especially problematic with lower price-point bikes, where the manufacturer will spec an external cam skewer, which will never have enough clamping force to hold a wheel in place under aggressive riding.

I'm currently looking at buying a new commuter/path bike, and I'm seriously considering getting a proper 29er hardtail, just because the cheaper 700c disc commuters still have QR levers. This is really more of a consumer education issue, people are used to QR levers, but a proper through axle is strictly better with discs, especially when you start comparing to compromised QR designs. Don't get me wrong, QR's work great with rim brakes. I'm got DA skewers on my road bike and they phenomenal, but its really about the appropriate tool for the job. Once through-axles become standard, it won't be an issue. From a manufacturing cost perspective, its probably a wash between a QR and through axle.