https://picclick.de/Absolute-Seltenheit-Answer-Manitou-4-Disc-Sachs-132360174010.html

https://www.pinkbike.com/photo/5488181/

Apparently, people also ground down the lips on the dropouts to make it easier to change wheels in a hurry (I’ve never seen this, but there were rumours about it).

also to make it easy to put a bike in a front wheel off roof rack ?

“Apparently, people also ground down the lips on the dropouts to make it easier to change wheels in a hurry”

https://www.uci.org/docs/default-source/equipment/clarificationguideoftheucitechnicalregulation-2018-05-02-eng_english.pdf?sfvrsn=fd56e265_92

Relevant section of the PDF linked to above:

It is essential that the equipment used in competition meets the prevailing quality and safety standards for bicycles. Mechanics and riders should also be aware of the ISO 4210 Standard on safety that applies to cycling equipment. They should refer to this Standard before modifying or adjusting any bicycle component. From 2019, all the frames and forks submitted to the UCI for approval will have to join a certification confirming the compliance with the ISO 4210 security norm. The certification template is available in the section « Equipment » of the UCI website.

Modifying equipment used in competition in relation to products supplied by the manufacturer is prohibited for obvious safety reasons. Whether it is a matter of modifying the length of the saddle, adapting approved wheels, filing off fork drop-out safety lugs or meeting the 3:1 rule by adding tape to handlebars. No modification of equipment that is not conducted by the manufacturer is authorised by the UCI without prior approval.

Strange this is that doping and a bunch of other things are also prohibited, but people still do it if they think they can get away with it.

Thanks for the Cotic link antigee ..some interesting stuff in there and clearly explained.

like above really not much of a issue, normally down to user error or a crap QR, so a cheap fix.
there is plenty of road QR disc bikes out ther with no issues.

Also it would cost Suspension manufacturers to redesign, change assembly procedure etc.
As the RH leg normally holds the most oil – (damping normally open bath back in the day) and if the seals fail (common ish back then) it would leak out and get on the Disc if fitted on the RH making braking interesting!
So have discs on the left is a bit of a fail safe in case the forkstarts leaking oil.

The lips on dropout ends are a fairly recent thing, I have old disc forks which don’t have lips. I think litigation may have precipitated the move to lips.

“And tension on bolts…have you any idea how strong steel is? (obvs not)”

Threads in magnesium lowers are less strong though

Repeated hard pull out on the threads, different materials, possible heat cycles, and lots of water for us British mud riders. Don’t think those bolts would ever come out of the brake was tension mounted. [exaggeration, but still a consideration.]

And by doing it the conventional way, no load on the threads at all.

^^^^^^Hence why they were known as lawyers lips

Cannondale place the caliper on the right of their Lefty forks

😉

It’s odd when you think about it because car calipers are frequently mounted on the front of the suspension upright. As well as motorbike’s right through to the 80’s.

Obviously motorbikes don’t have QR’s so either there must be other advantages to mounting them out front unless designers really didn’t care and just flipped a coin until armchair engineers and the marketing departments convinced them that rear mounted and radial bolts offered a benefit?

On motorbikes the reason given for the switch to behind the fork leg was steering inertia IIRC. I do’t see it myself.

there are two different forces involved in wheels coming out@:

Precessional forces from uneven side loading that is cyclic – that tends to unscrew QRs and also the ejecting force that pushes the wheel out

The lips on dropout ends are a fairly recent thing, I have old disc forks which don’t have lips.

Nah – Lawyer Lips an ancient. I had some Mag21’s in 1995 that had them, and I’m fairly sure the rigid forks they replaced had them, too (about ’92-’93). The 1990 Raleigh Mirage I had, didn’t.

Was the QR/Disc thing a real problem for most people

Clearly not for most people, but for the small number for whom it was a problem, it was quite a big problem.

From what I recall of the stuff at the time, the forces generated under braking are potentially more than half the clamping force required by the relevant ISO standard for QRs, which specifies a force on the wheel as a whole. Obviously the force from a disc brake is going to be very much on one side, so you’re relying on the extent to which QRs exceed the ISO standard, and how they behave under loads essentially acting on just one drop out.

Decent QRs, done up properly very comfortably exceed the standard, but relying on that isn’t a great place for a safety-critical device that is operated by end users.

That said, only time I’ve ever had an issue is with a through axle which had almost completely backed itself out of its thread by the time I stopped to find out why the disc brake was rubbing quite so much!

Road bikes heading towards using through-axles, but why?

https://yarchive.net/bike/disk_brake_qr.html

That said, only time I’ve ever had an issue is with a through axle which had almost completely backed itself out of its thread by the time I stopped to find out why the disc brake was rubbing quite so much!

Thats the precessional forces unscrewing it.

Must be the season of good will or something, I was expecting more sarcasm and abuse with this one.
He’s making his list and checking it twice, gonna find out who’s naughty or nice…

Didn’t someone die / have a serious accident in the UK because their front wheel came out?

Sorry, I remember now. Russell Pinder – paralysed from the chest down.

I have a Cotic fork with the brake on the right. Junk. It gets much more mucky that a left brake. No idea why. Way the crap goes I guess. Ges well with the rest of the bike though. An X made of railway irons.
The lawyers lips are a newish invention. Only started appearing in the early 90’s and a pain. Ground off most of my bikes as the whole point of a QR was just that. Proper QRs won’t come undone.
Why on the left? To match the rear of course.