Front disc brake with dropouts

[NATURAL ANKLING]

Hi,
When I started using QR's back then (road bike, rim brake), I was obsessed with making sure they were tight, and over tightning them through fear the wheel may drop off
I see my old QR cam eye (internal) has gone oval.

Funny that my cheap and nasty suntour forks aluminium has a deep recess for QR.
Even the steel forks I have, cheap disc suspension, have a pressed recess, whether this is simply following fashion or good design?

Front axel is somewhat different from rear which sees drive side forward force from drive, and NDS rearward force from brakes, in a conventional set up, so more likely rear the axel will creep to and fro.
As said seems bananas that a disc fork has no lawyers lips.
I don't give it a second thought nowadays, just check that the QR does clamp.

As said the location of axel is held by QR, and ideal would be by the solid part of axel.
Not a situation that would be normal in an industrial application.
But bicycles are unique in many ways, having to be lightweight and safe / reliable, somewhat work of art.

Good start would be a good QR, wonder what the OP is using?

Edited for grammar

[reohn2]

See up thread,I only use hex bolt skewers on my bikes

I think they are more likely to get to a decent tension than a cam-type QR, if my experiments are anything to go by. But it doesn't change the basic nature of the argument, only the detail.

cheers

The devil is in the detail,Ive not had problems with mine.

[Brucey]

The devil is in the detail,Ive not had problems with mine.

it often is, for sure. But I still think there is a problem there, especially for riders who often brake aggressively. I'm guessing that you are not in the habit of doing stoppies...?

cheers

[Adnepos]

I'm sure a bike made for discs would have lawyers lips on the drop outs, unless it was from the early days (1990's) of disc brakes, before the wheel ejecting habit was discovered. In those days Galaxys didn't come in a disc version.
I assume your QRs are original, at one point someone made front QRs with a bigger cam throw, so you could open the QR wide enough for it to slip past the lawyers lips.....

Well, my Galaxy is a 2013 version, sold as original kit by Spa Cycles. I think this was the first model in this series that featured disc brakes. There is no secondary retention system and no, I haven't filed the lawyers lips off!

I note that there was a voluntary recall relating to the front brake cabling (cable rather than hydraulic actuation) on my model of bike. But no mention of wheels dropping off.

If there were a legal requirement for secondary retention on front dropouts, I would be sending Dawes an email -with some strong wording because I believe that they tend to ignore customer contacts...

[reohn2]

The devil is in the detail,Ive not had problems with mine.

it often is, for sure. But I still think there is a problem there, especially for riders who often brake aggressively. I'm guessing that you are not in the habit of doing stoppies...?

cheers

No,I dont do stoppies but we did have a disc braked tandem for 7+ years without any problem as did the couple rode with regularly and they had no problems either.
Currently our Circe Helios tandem is similarly equiped but it's to early to give an opinion yet.
I've also owned four solo bikes with discs over the past 7 years with any disasters,no ovalising of the dropouts,no movement of the axle in the fork,in fact no problems wharsoever.
There are many other people riding around on similar bikes who's wheels don't self eject on applying the front brake so I'd say generally you concerns are unfounded except in extremis and or bad or careless maintenance

[MikeDee]

Properly desiged frames overcome the problem by having the dropouts facing forward so the wheel axle is forced into them rather than out of under braking

they are a better idea for sure but it doesn't stop the hub from moving around, and potentially becoming a slack fit over time through wear on the dropout faces etc.

The reaction force on the axle from a front brake caliper is backwards and downwards, whereas the usual load (arising from the road) is upwards and backwards; if the QR isn't tight enough vs the braking loads then the axle will still move about which (sooner or later) causes trouble.

BTW the tension force in a QR skewer is estimated to be between 500 and 1000kgf (depending on type and method of closure used. A 100kg rider braking hard will manage 100kg at the contact patch which means a 200kg leverage load on the axle (regardless of brake type, by taking moments about the fork crown) plus a torque reaction load that varies with the brake type. The latter load is estimated to be up to ~x5 the load at the contact patch (assuming a 160mm disc and a 700C wheel). So conceivably you could get 500-700kgf load trying to make the hub move in the dropouts.

Debates about the distribution of the load between the dropouts aside, it looks as if the coefficient of friction between the hub and dropouts needs to be between 0.5 and 1.0 to have any chance that the wheel might not move. Between random pieces of steel with a trace of oil present, it is very unlikely that the coefficient of friction will be that high.

My suspicion is that in most disc-braked bikes (with QR wheels and lawyer's lips) the front wheel moves under hard braking and then doesn't always move back again during normal riding.

Arguably the lips are on the wrong face of the dropout, anyway; it would be more secure if the locknuts see the load from the lips, not the QR skewer, which isn't really designed for it.

cheers

I believe an article by James Annan said that all that movement also causes the skewer nut to unscrew, so it is prudent to check your skewer tension often.

[Brucey]

I believe an article by James Annan said that all that movement also causes the skewer nut to unscrew, so it is prudent to check your skewer tension often.

it may well have done, and indeed it may be possible for the nut to unscrew. But if there is any repeated relative movement between parts, wear will cause the tension in the skewer to be lost anyway.

It isn't uncommon for the paint wearing off dropouts to causes conventional wheels to loosen in a new frame; with disc brakes it seems more likely and of course more harmful.

cheers

[Brucey]

....There are many other people riding around on similar bikes who's wheels don't self eject on applying the front brake so I'd say generally you concerns are unfounded except in extremis and or bad or careless maintenance

I don't think I have seen a factory built bike with disc brakes and conventionally oriented dropouts that didn't also have lawyer's lips. If the QR fails to restrain the wheel properly in such bikes, the result is not usually wheel ejection, it is that the brake rubs and needs adjusting constantly.

Plenty of people complain about that....

I think it is a very common issue that the skewer does not hold the wheel adequately; I rarely see an MTB (with QR wheels and disc brakes) where the wheels obviously haven't been on the move...

cheers

[CJ]

I thought the retention tabs - "lawyers lips" - had been a legal requirement on the front forks for quite some time?

Done a search and not found anything about these tabs being a legal requirement -I don't have a problem with them by the way, I wish my forks had them. How could they be a legal requirement when many bikes have thru' axles so no way of sensibly deploying them -or other secondary retention system?

"Lawyers lips" is a colloquial term, so I'm not surprised that a search did not reveal the fact that some such feature has been a legal requirement (at the point of sale only - you can file 'em off later if you wish) on any new bicycle sold in EU for at least the last ten years. Here's a link to the page about these regulations I originally wrote for CTC. I suggest you read that, as it will tell you how it comes to pass that any new bike, since long before disc brakes became available on touring bikes, has to conform with the relevant British/EU Standard, or else the retailer is committing an offence.

I wish I could post a link to the Standard, but it's a copyright publication behind paywalls, which is probably another reason your searches didn't bear fruit. And the pdf I brought with me when I left the employ of the erstwhile CTC, does not allow copy and paste, so I'll have to paraphrase.

It does not mention lawyers lips. It does not even say front wheels must be equipped with secondary retention devices. What it says is that the wheel must not fall out when the quick-release is opened (or axle nuts etc are undone by one full turn) and the wheel is pulled in what I will simply call the out direction with a force of 100N. It's up to the manufacturer how he ensures that can't happen. Putting lawyer's lips on slotted dropouts just happens to be the cheapest and easiest way with conventional slotted dropouts. A thru-axle design is another way, more capable of sustaining the far higher ejection forces that may arise with a disc brake, which wasn't a consideration on the likes of 'Trekking Bikes' when my 2005 edition of the Standard was written. So that clause may well have been beefed up a bit by now. But sure as eggs is eggs, it'll still be in there.

So the sale of that bike was certainly illegal. If prosecuted, the retailer will of course send the chicken home to roost with his supplier.

[gloomyandy]

That's interesting. I bought a TT bike frameset about 3 years ago (brand new). The forks on that do not seem to have any sort of retention device, if you open the QR the wheel will drop out. Should this frame have been sold like that? I don't have any problem with it as I often change front wheels and remove the wheel for transport, so in some respects it is easier the way it is, but I'm just curious.

[CJ]

That's interesting. I bought a TT bike frameset about 3 years ago (brand new). The forks on that do not seem to have any sort of retention device, if you open the QR the wheel will drop out. Should this frame have been sold like that? I don't have any problem with it as I often change front wheels and remove the wheel for transport, so in some respects it is easier the way it is, but I'm just curious.

Sale of a bare frameset isn't covered by the Regs or the Standard, just a complete (or near complete) bike. And if you tried to argue the matter under General Product Safety, that the frame ought to be capable of assembly into a conforming bicycle, they could argue that this frame is designed for use with (goofy) add-on secondary retention devices or since it's a time-trial frameset then it's for use in sanctioned competitive events and hence beyond any published standard's scope.

[gloomyandy]

Thanks CJ, no intention of complaining, was just curious really as to what the situation may be.

[Valbrona]

I know little about Dawes Galaxy. And I have a low opinion of Dawes. But are the dropouts on the Galaxy Disc fork front-facing? They will still need lips, but with disc braking they are not going to jump out of the fork in the case of front-facing dropouts.

[rmurphy195]

The info pointed to by CJ is interesting - do the regulations apply, I wonder, when your LBS orders in the frame of your choice and builds it into a complete bike for use on the public road?

The reason I ask is that I did have this done a couple of years back, the bike was built but I didn't ask for reflectors or lamps, and specified a pair of pedals that did not have reflectors fitted. The tyres had reflective sidewalls, but his wasn't consciously asked for.

So the LBS supplied a bike without reflectors or lamps to front and rear, and without reflectors on the pedals. Does this mean that technically they were infringing the regs? If so, it's something that bike shops need to be aware of.

Ref the Dawes - my original Galaxy had the "lawyers lips" on the front fork, and its replacement (the Condor the LBW built for me) has the same. I can't imagine why Dawes haven't fitted these to the OP's bike. Anyone else got one?

[Adnepos]

..."Lawyers lips" is a colloquial term, so I'm not surprised that a search did not reveal the fact that some such feature has been a legal requirement (at the point of sale only - you can file 'em off later if you wish) on any new bicycle sold in EU for at least the last ten years. Here's a link to the page about these regulations I originally wrote for CTC. I suggest you read that, as it will tell you how it comes to pass that any new bike, since long before disc brakes became available on touring bikes, has to conform with the relevant British/EU Standard, or else the retailer is committing an offence.

I wish I could post a link to the Standard, but it's a copyright publication behind paywalls, which is probably another reason your searches didn't bear fruit. And the pdf I brought with me when I left the employ of the erstwhile CTC, does not allow copy and paste, so I'll have to paraphrase.

It does not mention lawyers lips. It does not even say front wheels must be equipped with secondary retention devices. What it says is that the wheel must not fall out when the quick-release is opened (or axle nuts etc are undone by one full turn) and the wheel is pulled in what I will simply call the out direction with a force of 100N. It's up to the manufacturer how he ensures that can't happen. Putting lawyer's lips on slotted dropouts just happens to be the cheapest and easiest way with conventional slotted dropouts. A thru-axle design is another way, more capable of sustaining the far higher ejection forces that may arise with a disc brake, which wasn't a consideration on the likes of 'Trekking Bikes' when my 2005 edition of the Standard was written. So that clause may well have been beefed up a bit by now. But sure as eggs is eggs, it'll still be in there.

So the sale of that bike was certainly illegal. If prosecuted, the retailer will of course send the chicken home to roost with his supplier.

From what you write, Statutory Instrument 2010 No. 198, which is the most recent enactment of the Pedal Bicycles Safety Regulations, is not a legal basis for the illegality of selling cycles that do not have a secondary retention system. The legal basis would be The General Product Safety Regulations 2005 (GPSR) and a reliance on ISO 4210-6 being a product safety code of good practice in the cycle sector. GPSR would lay culpability with the producer rather than the distributor.

Can you confirm that you are quoting ISO as the standard for secondary retention?

Do you agree that the producer has a case to answer rather than the distributor?