How important are these small bits?

[NHAero]

The conical springs on QRs

The teeny bolts on rim brake pad holders, that keep the pads from sliding out if the holders are mounted on the wrong sides with the open end facing front?

And bonus question - why are the Swissstop carbon pads I just mounted on my Supersix labeled right and left?

[ColonelJLloyd]

Not.

Kinda. They're a failsafe.

To keep folks from more trial and error than necessary.

[tellyho]

I've tried to use QR with one spring missing. It works, but it's not easy.

As far as I know the L/R pads are slightly beveled to match the rim profile.

I suspect you could go without the fixing bolt on cartridge pads. You try and get back to us

[gravelreformist]

QR springs are for convenience, not safety.

You could probably go a long time on the road without missing the pad fixing bolts, although if you do any off-road, gravel, or other technical riding, it is possible for wheel rotation to work backwards under certain circumstances, forcing the pads from the holders. Yes, I've actually had this happen in my younger days.

[Hindmost]

Originally Posted by NHAero

The conical springs on QRs

Without them the skewers are no longer quick.

[ssb94]

#1. No idea
#2. Strictly speaking, probably not (under ideal conditions the force always pushes them into the holder). But is that something you want to risk? Especially with carbon rims!
#3. The pads are usually tapered, curved, and have an indent for the bolts you mentioned. If they were on the wrong side, something wouldn't fit properly.

[Mark McM]

Originally Posted by gravelreformist

QR springs are for convenience, not safety.

You could probably go a long time on the road without missing the pad fixing bolts, although if you do any off-road, gravel, or other technical riding, it is possible for wheel rotation to work backwards under certain circumstances, forcing the pads from the holders. Yes, I've actually had this happen in my younger days.

In the old days, many brake shoes had no pad fixing bolts, and the pads simply slide in and out of the back of the holder. Many years ago, one of my neighbors installed new brake shoes on his front brake, but he installed them backwards, so the open end was facing forward. The first time he applied his front brake, the pads flew out of the front of the shoes, leaving him with no front brake.

The brake pad bolts are likely the equivalent of lawyer lips on fork dropouts.

For the other questions:

#1 The conical springs are just for the convenience of holding the ends of the skewer apart when the lever is open, so the user doesn't have to center the skewer to guide the axle into the dropouts (this is similar to the tire guide wings on the bottoms of brake shoes). Once the skewer is closed, the springs serve no function.

#3 Brake pads often have an arch shape, to match the curve of the brake track. The pad retention screws will prevent the pads from being mounted backwards, but if right and left are mixed up the pads will be upside down, so the arch of the pads will also be upside down.

[NHAero]

Originally Posted by Hindmost

Without them the skewers are no longer quick.

I knew there was a good reason!

[bikinchris]

Originally Posted by NHAero

The conical springs on QRs

The teeny bolts on rim brake pad holders, that keep the pads from sliding out if the holders are mounted on the wrong sides with the open end facing front?

And bonus question - why are the Swissstop carbon pads I just mounted on my Supersix labeled right and left?

You need to have either both conical springs or no springs. Their only purpose is to keep the QR centered.
When I'm replacing worn brake pads I remove the keeper screws, apply the brakes slightly and turn the wheel backward. Both pads come out at the same time. If you were standing over your bike and bumped the brake lever and rolled the bike backwards, you might not have a brake pad.
Most rim brake pad holders are tapered and angled so the pads are labelled to keep you from putting them upside down.

[unterhausen]

I have had pads fall out without the retainers. In my case it was retaining clips. It usually happens when stopped for me. Apparently I use my brakes when backing the bike up, who knew?

[.RJ]

Originally Posted by unterhausen

I have had pads fall out without the retainers. In my case it was retaining clips. It usually happens when stopped for me. Apparently I use my brakes when backing the bike up, who knew?

When its time to change pads, remove the bolts, grab the brake lever and roll the wheel backwards to pop them out.

[avalonracing]

Trying to save two grams, are we?

[NHAero]

Originally Posted by avalonracing

Trying to save two grams, are we?

Just curious if they were a CPSC contribution like lawyer lips or had a real function, and I've received some useful answers.

[Mark McM]

Originally Posted by NHAero

Just curious if they were a CPSC contribution like lawyer lips or had a real function, and I've received some useful answers.

Actually, "Lawyer Lips" are not mandated by CPSC (or else they would have been called "CPSC Lips"). CPSC only requires secondary retention devices for front wheels not held on with quick release levers. Here's the text from the CPSC bicycle regulations:

§ 1512.12 Requirements for wheel hubs.

All bicycles (other than sidewalk bicycles) shall meet the following requirements:

(a) Locking devices. Wheels shall be secured to the bicycle frame with a positive lock device. Locking devices on threaded axles shall be tightened to the manufacturer's specifications.

(1) Rear wheels. There shall be no relative motion between the axle and the frame when a force of 1,780 N (400 lbf) is applied symmetrically to the axle for a period of 30 seconds in the direction of wheel removal.

(2) Front wheels. Locking devices, except quick-release devices, shall withstand application of a torque in the direction of removal of 17 N-m (12.5 ft-lb).

(b) Quick-release devices. Lever-operated, quick-release devices shall be adjustable to allow setting the lever position for tightness. Quick-release levers shall be clearly visible to the rider and shall indicate whether the levers are in a locked or unlocked position. Quick-release clamp action shall emboss the frame or fork when locked, except on fiber reinforced plastics.

(c) Front hubs. Front hubs not equipped with lever-operated quick-release devices shall have a positive retention feature that shall be tested in accordance with the front hub retention test, § 1512.18(j)(3), to assure that when the locking devices are released the wheel will not separate from the fork.

The addition of "Lawyer lips" was likely instigated by the many, many law suits from bike rider's whose QR front wheels fell off, and who claimed that it only happened because the bike was "faulty".


As far as brake pad retaining screws/clips, these might have been a response to the "rocking" test in the CPSC regulations:

1512.5 Requirements for braking system.

(a) Braking system. Bicycles shall be equipped with front- and rear-wheel brakes or rear-wheel brakes only.

(b) Handbrakes. Handbrakes shall be tested at least ten times by applying a force sufficient to cause the handlever to contact the handlebar, or a maximum of 445 N (100 lbf), in accordance with the loading test, § 1512.18(d)(2), and shall be rocked back and forth with the weight of a 68.1 kg (150 lb) rider on the seat with the same handbrake force applied in accordance with the rocking test, § 1512.18(d)(2)(iii); there shall be no visible fractures, failures, movement of clamps, or misalignment of brake components.

(1) Stopping distance. A bicycle equipped with only handbrakes shall be tested for stopping distance by a rider of at least 68.1 kg (150 lb) weight in accordance with the performance test, § 1512.18(d)(2) (v) and (vi), and shall have a stopping distance of no greater than 4.57 m (15 ft) from the actual test speed as determined by the equivalent ground speed specified in § 1512.18(d)(2)(vi).

(2) Hand lever access. Hand lever mechanisms shall be located on the handlebars in a position that is readily accessible to the rider when in a normal riding position.

(3) Grip dimension. The grip dimension (maximum outside dimension between the brake hand lever and the handlebars in the plane containing the centerlines of the handgrip and the hand brake lever) shall not exceed 89 mm (31⁄2 in) at any point between the pivot point of the lever and lever midpoint; the grip dimension for sidewalk bicycles shall not exceed 76 mm (3 in). The grip dimension may increase toward the open end of the lever but shall not increase by more than 12.7 mm (1⁄2 in) except for the last 12.7 mm (1⁄2 in) of the lever. (See figure 5 of this part 1512.)

(4) Attachment. Brake assemblies shall be securely attached to the frame by means of fasteners with locking devices such as a lock washer, locknut, or equivalent and shall not loosen during the rocking test, § 1512.18(d)- (2)(iii). The cable anchor bolt shall not cut any of the cable strands.

(5) Operating force. A force of less than 44.5 N (10 lbf) shall cause the brake pads to contact the braking surface of the wheel when applied to the handlever at a point 25 mm (1.0 in) from the open end of the handlever.

(6) Pad and pad holders. Caliper brake pad shall be replaceable and adjustable to engage the braking surface without contacting the tire or spokes and the pad holders shall be securely attached to the caliper assembly. The brake pad material shall be retained in its holder without movement when the bicycle is loaded with a rider of at least 68.1 kg (150 lb) weight and is rocked forward and backward as specified in the rocking test, § 1512.18(d)(2)(iii).

Note that not all brake pads have retaining screws or clips. For example, Campagnolo has used a tight friction fit to retain pads in holders.

[carpediemracing]

Originally Posted by Mark McM

The addition of "Lawyer lips" was likely instigated by the many, many law suits from bike rider's whose QR front wheels fell off, and who claimed that it only happened because the bike was "faulty".

When I started an IT job a while ago, my boss found out I know something about bikes. He immediately came over and asked me about the retaining clips on Schwinns (I'm sure people know about this but I'll explain, they used an actual device, not just a lip on the dropouts). He proudly claimed that it was because of him that those were there. He also pointed to his (pretty obviously) fake teeth and said he lost most of his teeth when his front wheel fell off.

He used to coach football at a local-to-him school (not in the area - I want to say NJ but I don't remember) and he left practice one day, rode off the curb, and the front wheel fell off. He said that he did that all the time and nothing happened until that day.

Thing is, the guy was maybe not super people-skilled. In fact, he was one of the reasons I left the company. Not because he was mean, he was just clueless.

My theory (and it's just a theory) is that one or a few of his football players decided to play a joke on him and loosened the skewer. It would explain why he was able to ride the bike around for a long time without anything happening, and then one day the front wheel falls out.

On that day he was obviously quite hurt and I imagine that if someone did play a joke on him, they weren't going to fess up if there was a scapegoat. And of course there was - the bike manufacturer.

From Sheldon Brown's site, the patent drawing of the clip:


And just below that, a picture of a clip on a bike:


It was quite ingenious. The long flat piece was mounted to the axle but was free floating, meaning it spun independent of the axle. It was spring steel.

There was a hole in the end that touched the fork (the "top" if you will), and a screw in the fork (which had its own braze-on) would fit in it. Once the screw head was in the lever, you couldn't take out the front wheel, until either the screw broke or the screw broke off the fork.

The lever thing had a wedge shape on one side. You could swing the lever up to the fork and the wedge would allow the lever to smoothly slide over the screw head, and then the lever would snap into place with a reassuring and distinctive sound.

To remove a wheel, you simply pushed in on the levers and let them swing down - it was quickest to do both at once. They would dangle like a pair of ponytails on the wheel. Then undo the skewer and the wheel would drop down. On a good day it was a half second slower than no clips.

It was much, much better than the axle washers with the hook that hooked into a corresponding slot in the dropout. But those washers were cheap and only required a slight modification to the dropout.

The Schwinn clips would be much faster than unscrewing the QR to clear the lawyer tabs.

The clips cost money, added weight and complexity, required a screw mount in each fork blade... so it disappeared.