Brake caliper flex

fwgx

Hi,
I have a 2013 Felt Z85 which has no-name brake calipers fitted. I've never been too happy with the braking performance of the bike, but initially I put this down to road bike brakes just not being as good. I recently decided that new pads would do the trick, so went for some Dura Ace pad inserts. They're a little better, but not loads.

So I was looking more closely at the calipers and what they're doing when I squeeze the leavers. It seems to me that the metal is flexing once the pads are on the rims, so as I squeeze harder it's not resulting in as much force on the rim as I'd expect - it's being absorbed by the metal in the caliper instead of applied to the wheel rim.

For reference I made a video showing the flex: http://www.youtube.com/watch?v=QjZz1jPk ... e=youtu.be

I was looking at getting a set of 105 calipers front and rear, but first of all I don't know if this is normal or not. I have read great things about the 105 calipers being a day and night difference, but I don't know if it will help me and whether it's true - I've seen lots of other people saying any old caliper will do.

Any help / adive would be much appreciated.

topdude

Yes, i've noticed the same with Tektro, Tiagra and Veloce !
Maybe 105 and Ultegra don't flex as much ?
Will be interesting to see if anyone checks theirs and reports back.

stueys

My Tiagra calipers do it, think the newer Tigara is better. It results in very crap braking performance, I've been waiting to get enough wear on the chain set to swap the whole thing out. There now thankfully.

kajjal

I weigh about 100kg and switched to 105's which gave me much better braking performance in the dry. In the wet the stock pads are poor but swisstop greens or similar work OK in the wet.

Haven't checked for flexing but they seem fine.

simon_masterson

Braking is friction - The surfaces involved therefore can have a huge influence on braking performance.If you've ever ridden in torrential rain on a bike with old Weinmann brakes and steel rimmed wheels, then you will know what I'm talking about - and if you haven't, then you have no idea what bad braking performance is.

Seriously though, whilst brake caliper flex obviously isn't helping, the pads you use can also make a big difference. I've never heard a good word for Shimano's own pads. Something like SwissStop or KoolStop could enhance your braking significantly.

fwgx

The Dura Ace pads I have now get rave reviews: http://www.wiggle.co.uk/shimano-dura-ac ... f-inserts/

sungod

read the first five pages of the dura ace reviews

then read the first five pages of the reviews http://www.wiggle.co.uk/swissstop-flash ... ance-pads/

the swissstop are waaaaaay better pads than the shimano ones, i've tried both, there's no contest, especially in the wet

bigflangesmallsprocket

I always thought my Veloce stoppers worked quite well, even with my placcy Mirage levers (not fitted at the mo, Miche Performance calipers waiting to be tried out on 'new' frame), but then again, there's not a lot of me to stop. Have to admit, that doesn't look too good.

thescouselander

fwgx wrote:

Hi,
I have a 2013 Felt Z85 which has no-name brake calipers fitted. I've never been too happy with the braking performance of the bike, but initially I put this down to road bike brakes just not being as good. I recently decided that new pads would do the trick, so went for some Dura Ace pad inserts. They're a little better, but not loads.

So I was looking more closely at the calipers and what they're doing when I squeeze the leavers. It seems to me that the metal is flexing once the pads are on the rims, so as I squeeze harder it's not resulting in as much force on the rim as I'd expect - it's being absorbed by the metal in the caliper instead of applied to the wheel rim.

For reference I made a video showing the flex: http://www.youtube.com/watch?v=QjZz1jPk ... e=youtu.be

I was looking at getting a set of 105 calipers front and rear, but first of all I don't know if this is normal or not. I have read great things about the 105 calipers being a day and night difference, but I don't know if it will help me and whether it's true - I've seen lots of other people saying any old caliper will do.

Any help / adive would be much appreciated.

This is simply not possible - force cannot be absorbed as you describe. Yes the caliper is bending but the additional force you put into the caliper is still equally opposed by the rim against brake block once the caliper stops bending and the forces equalise. That is the force on the brake block / rim will still have increased even though the calliper bent slightly.

In my experience the biggest factor determining how well brakes work is using the right brake pads and keeping the wheel rim clean. I usually wipe a rag soaked in a bit of white spirit round the brake track on the rim to remove any grease etc.

rolf_f

thescouselander wrote:

This is simply not possible - force cannot be absorbed as you describe. Yes the caliper is bending but the additional force you put into the caliper is still equally opposed by the rim against brake block once the caliper stops bending and the forces equalise. That is the force on the brake block / rim will still have increased even though the calliper bent slightly.

In my experience the biggest factor determining how well brakes work is using the right brake pads and keeping the wheel rim clean. I usually wipe a rag soaked in a bit of white spirit round the brake track on the rim to remove any grease etc.

Stop spoiling it for everyone - folk on here just want to buy new calipers and they don't want you pointing out that the best calipers in the world are going to feel no different to the ones they've already got on account of the braking power being mostly about the stuff that's pressing against each other - ie pads and rims! There's no fun in buying new pads and rags!

And yes, just to confirm - Centaur and Super Record are exactly the same. As I expected them to be. And that will be the same as Veloce.

Grill

sungod wrote:

read the first five pages of the dura ace reviews

then read the first five pages of the reviews http://www.wiggle.co.uk/swissstop-flash ... ance-pads/

the swissstop are waaaaaay better pads than the shimano ones, i've tried both, there's no contest, especially in the wet

This.

simon_masterson

That and actually applying the brakes correctly.

stueys

thescouselander wrote:

fwgx wrote:

Hi,
I have a 2013 Felt Z85 which has no-name brake calipers fitted. I've never been too happy with the braking performance of the bike, but initially I put this down to road bike brakes just not being as good. I recently decided that new pads would do the trick, so went for some Dura Ace pad inserts. They're a little better, but not loads.

So I was looking more closely at the calipers and what they're doing when I squeeze the leavers. It seems to me that the metal is flexing once the pads are on the rims, so as I squeeze harder it's not resulting in as much force on the rim as I'd expect - it's being absorbed by the metal in the caliper instead of applied to the wheel rim.

For reference I made a video showing the flex: http://www.youtube.com/watch?v=QjZz1jPk ... e=youtu.be

I was looking at getting a set of 105 calipers front and rear, but first of all I don't know if this is normal or not. I have read great things about the 105 calipers being a day and night difference, but I don't know if it will help me and whether it's true - I've seen lots of other people saying any old caliper will do.

Any help / adive would be much appreciated.

This is simply not possible - force cannot be absorbed as you describe. Yes the caliper is bending but the additional force you put into the caliper is still equally opposed by the rim against brake block once the caliper stops bending and the forces equalise. That is the force on the brake block / rim will still have increased even though the calliper bent slightly.

In my experience the biggest factor determining how well brakes work is using the right brake pads and keeping the wheel rim clean. I usually wipe a rag soaked in a bit of white spirit round the brake track on the rim to remove any grease etc.

All I can say us that I run swiss stop pads on both my road bikes. My dura ace bike stops brilliantly, great modulation and power. Pretty good in the wet as well. My Tigara bike stops ok in the dry, poor in the wet. Same pads on both.

rolf_f

Stueys wrote:

All I can say us that I run swiss stop pads on both my road bikes. My dura ace bike stops brilliantly, great modulation and power. Pretty good in the wet as well. My Tigara bike stops ok in the dry, poor in the wet. Same pads on both.

So we should be able to find plenty of folk who can say that Tiagra brakes are bendier than Dura Ace and no-one who finds them much the same unless there are other factors at play in your case (eg dirty vs clean rims etc).

It seems odd though. Unless the Tiagra design was fundamentally flawed, for them to be flexier than the Dura Ace calipers Shimano would have had to deliberately engineered them to be that way (given that presumably they are both at heart simple alloy levers) which seems rather poor!

cougie

Simon Masterson wrote:

Braking is friction - The surfaces involved therefore can have a huge influence on braking performance.If you've ever ridden in torrential rain on a bike with old Weinmann brakes and steel rimmed wheels, then you will know what I'm talking about - and if you haven't, then you have no idea what bad braking performance is.

Yes just ride an old bike and you'll be more than pleased with your tektro braking ! :-)

Grill

Rolf F wrote:

Stueys wrote:

All I can say us that I run swiss stop pads on both my road bikes. My dura ace bike stops brilliantly, great modulation and power. Pretty good in the wet as well. My Tigara bike stops ok in the dry, poor in the wet. Same pads on both.

So we should be able to find plenty of folk who can say that Tiagra brakes are bendier than Dura Ace and no-one who finds them much the same unless there are other factors at play in your case (eg dirty vs clean rims etc).

It seems odd though. Unless the Tiagra design was fundamentally flawed, for them to be flexier than the Dura Ace calipers Shimano would have had to deliberately engineered them to be that way (given that presumably they are both at heart simple alloy levers) which seems rather poor!

Makes perfect sense. Dura Ace is the halo groupset of the line so both the design and the materials should be superior to Tiagra (this is apparent by their lighter weight, superior materials and fantastic stopping power). Make components lighter and stiffer also makes them more expensive which is where the difference in price comes in. Example; DA rings are cold-forged, Tiagra rings are not. There's also trickle down with the tech which is shown in my 6800 calipers.

Bar Shaker

thescouselander wrote:

This is simply not possible - force cannot be absorbed as you describe. Yes the caliper is bending but the additional force you put into the caliper is still equally opposed by the rim against brake block once the caliper stops bending and the forces equalise. That is the force on the brake block / rim will still have increased even though the calliper bent slightly.

That is not the case if the arm is flexing.

Ask yourself about how force transfer to the pads would be affected if the caliper arms were:
1) more flexible
2) less flexible.

Think about how springs (flexible structures) store potential energy and then give this back when the force is removed. Is a flexible caliper arm storing potential energy, or transferring it to the pad?

The stiffness of the arms and the friction of the pads are both important factors.

rolf_f

Grill wrote:

Rolf F wrote:

Stueys wrote:

All I can say us that I run swiss stop pads on both my road bikes. My dura ace bike stops brilliantly, great modulation and power. Pretty good in the wet as well. My Tigara bike stops ok in the dry, poor in the wet. Same pads on both.

So we should be able to find plenty of folk who can say that Tiagra brakes are bendier than Dura Ace and no-one who finds them much the same unless there are other factors at play in your case (eg dirty vs clean rims etc).

It seems odd though. Unless the Tiagra design was fundamentally flawed, for them to be flexier than the Dura Ace calipers Shimano would have had to deliberately engineered them to be that way (given that presumably they are both at heart simple alloy levers) which seems rather poor!

Makes perfect sense. Dura Ace is the halo groupset of the line so both the design and the materials should be superior to Tiagra (this is apparent by their lighter weight, superior materials and fantastic stopping power). Make components lighter and stiffer also makes them more expensive which is where the difference in price comes in. Example; DA rings are cold-forged, Tiagra rings are not. There's also trickle down with the tech which is shown in my 6800 calipers.

Shimano must be relieved that in this cynical age there are still some folk that read and have faith in their marketing spiel!

Possibly a good reason not to buy Shimano though - since Campagnolo don't penalise their lesser groupsets with inferior performing brakes (just a bit heavier -which is fair enough).

Bar Shaker wrote:

The stiffness of the arms and the friction of the pads are both important factors.

Don't forget the pads - they are flexing as well. Incidentally, if you want to see real flexiness in calipers - have a look at a pair of Weinmann centre pulls (from the 70s/80s). With a set of hard blocks firmly pressed against the rim you can continue to move the brake lever an alarmingly long way with only the cable end of the caliper arms moving!

Grill

Rolf F wrote:

Grill wrote:

Rolf F wrote:

Stueys wrote:

All I can say us that I run swiss stop pads on both my road bikes. My dura ace bike stops brilliantly, great modulation and power. Pretty good in the wet as well. My Tigara bike stops ok in the dry, poor in the wet. Same pads on both.

So we should be able to find plenty of folk who can say that Tiagra brakes are bendier than Dura Ace and no-one who finds them much the same unless there are other factors at play in your case (eg dirty vs clean rims etc).

It seems odd though. Unless the Tiagra design was fundamentally flawed, for them to be flexier than the Dura Ace calipers Shimano would have had to deliberately engineered them to be that way (given that presumably they are both at heart simple alloy levers) which seems rather poor!

Makes perfect sense. Dura Ace is the halo groupset of the line so both the design and the materials should be superior to Tiagra (this is apparent by their lighter weight, superior materials and fantastic stopping power). Make components lighter and stiffer also makes them more expensive which is where the difference in price comes in. Example; DA rings are cold-forged, Tiagra rings are not. There's also trickle down with the tech which is shown in my 6800 calipers.

Shimano must be relieved that in this cynical age there are still some folk that read and have faith in their marketing spiel!

Possibly a good reason not to buy Shimano though - since Campagnolo don't penalise their lesser groupsets with inferior performing brakes (just a bit heavier -which is fair enough).

You have to go to Record to get the central fulcrum with bearing system which they say will keep "braking modulatation, reliability, and performance consistently maintained over time." SRAM, TRP, AVID and everyone else do the same. Why you would expect the same performance over different groupsets is beyond me (does Athena shift as nicely as SUper Record?).

rolf_f

Grill wrote:

You have to go to Record to get the central fulcrum with bearing system which they say will keep "braking modulatation, reliability, and performance consistently maintained over time." SRAM, TRP, AVID and everyone else do the same. Why you would expect the same performance over different groupsets is beyond me (does Athena shift as nicely as SUper Record?).

Not talking about the shifting (though, if most of the parts are the same - as they were pre Powertorque/Ultratorque, why not?). But as to the brakes. As I said, there isn't really much difference between Centaur Skeleton and SR. The design of the arms is the same, the metal is the same and that's pretty much what will define the performance. Maintenance of that performance over time? Yes - that is another issue. All I can go on is the performance of my Centaur brakes over 18,000 miles of often terrible weather. They can get affected by grit. Performance has slightly degraded - but then I haven't got round to changing the cables yet - changing the outers on the rear mech the other day certainly made a big difference so maybe I should get round to doing that. So far, the bushing doesn't appear to be worn so I think the benefits of that "central fulcrum with bearing system" (I think by this they mean 'bearing'! ) but maybe another few 10's of thousands of miles will show it to be a weakness.

Much of what Campag says confers great bragging rights (to be honest, I can't really tell that the lever bodies on my Centaur shifters are plastic rather than composite as they would be on Record but it's nice to know if you do have Record), a modicum of lightness, a flashier finish, possibly some increased longevity (though, in other cases, reduced longevity) but minimal difference that you'd actually notice on a bike (unless £1500 of investment demands that you notice it.....).

Of course they all do the same. By banging in a bearing or two, increasing the composites and making a nicer looking finish, the manufacturers get to increase the retail price of a groupset by four times or more without it costing them so much more to make. I'd love to see what the relative margins are on Veloce vs Super Record.....

BTW - Avid = SRAM.

Runtothehills

Bar Shaker wrote:

thescouselander wrote:

This is simply not possible - force cannot be absorbed as you describe. Yes the caliper is bending but the additional force you put into the caliper is still equally opposed by the rim against brake block once the caliper stops bending and the forces equalise. That is the force on the brake block / rim will still have increased even though the calliper bent slightly.

That is not the case if the arm is flexing.

Ask yourself about how force transfer to the pads would be affected if the caliper arms were:
1) more flexible
2) less flexible.

Think about how springs (flexible structures) store potential energy and then give this back when the force is removed. Is a flexible caliper arm storing potential energy, or transferring it to the pad?

The stiffness of the arms and the friction of the pads are both important factors.

Assuming the same lever arm and force in the cable the force transfer to the pad will be exactly the same. You might have to pull the brake lever further to get there (which is where the stored energy come in) but the force on the pad for a given force on the lever will not change. Force does not equal energy.

The stiffness of the arms will have an effect on the feel of the brakes but not the braking force.

Think about sitting on a bike with suspension (wrong forum but still), you will exert a certian force on the ground because of your weight. Now lock the suspension out and sit on the bike again - will that force change? Of course it won't, even though the system transfering the force of your weight to the ground (the bike) is a lot stiffer.

taon24

Runtothehills wrote:

Assuming the same lever arm and force in the cable the force transfer to the pad will be exactly the same. You might have to pull the brake lever further to get there (which is where the stored energy come in) but the force on the pad for a given force on the lever will not change. Force does not equal energy.

The stiffness of the arms will have an effect on the feel of the brakes but not the braking force.

Think about sitting on a bike with suspension (wrong forum but still), you will exert a certian force on the ground because of your weight. Now lock the suspension out and sit on the bike again - will that force change? Of course it won't, even though the system transfering the force of your weight to the ground (the bike) is a lot stiffer.

However arm flex will affect the time of onset of braking force. You will need to pull the cable further and harder to brake with the same force as a stiffer calliper. In your suspension example the idea of suspension is to smooth the ride, by increasing the time period over which the change of force. You sit on your bike and you will sink further before the bike resists your whole weight. While you are sinking the force the bike exerts on the ground is less than that exerted by your whole weight when stationary.

The effect will be that you need to brake for longer for the same braking effect, which is a definite disadvantage, and that you will continue braking once you release your brake levers as the callipers flex back to their original shape.

simon_masterson

cougie wrote:

Simon Masterson wrote:

Braking is friction - The surfaces involved therefore can have a huge influence on braking performance.If you've ever ridden in torrential rain on a bike with old Weinmann brakes and steel rimmed wheels, then you will know what I'm talking about - and if you haven't, then you have no idea what bad braking performance is.

Yes just ride an old bike and you'll be more than pleased with your tektro braking ! :-)

I still do ride old bikes. With Tektro brakes too.

I look back on it with some disbelief, but a couple of years back I was riding around with brakes that pretty much didn't work at all. The turning point came when I pretty much had to intentionally ride into a hedge to stop for oncoming traffic, and then later in the same ride almost ended up under a lorry.

That said, my front wheel was in a bad way recently and I ended up needing to sub one of my old steel rims onto the main bike, and even with perfectly functional brakes, riding home in a rainstorm was still a bit hairy; hence I take it with a large pinch of salt when I hear complaints about modern stopping equipment.

Runtothehills

taon24 wrote:

Runtothehills wrote:

Assuming the same lever arm and force in the cable the force transfer to the pad will be exactly the same. You might have to pull the brake lever further to get there (which is where the stored energy come in) but the force on the pad for a given force on the lever will not change. Force does not equal energy.

The stiffness of the arms will have an effect on the feel of the brakes but not the braking force.

Think about sitting on a bike with suspension (wrong forum but still), you will exert a certian force on the ground because of your weight. Now lock the suspension out and sit on the bike again - will that force change? Of course it won't, even though the system transfering the force of your weight to the ground (the bike) is a lot stiffer.

However arm flex will affect the time of onset of braking force. You will need to pull the cable further and harder to brake with the same force as a stiffer calliper. In your suspension example the idea of suspension is to smooth the ride, by increasing the time period over which the change of force. You sit on your bike and you will sink further before the bike resists your whole weight. While you are sinking the force the bike exerts on the ground is less than that exerted by your whole weight when stationary.

The effect will be that you need to brake for longer for the same braking effect, which is a definite disadvantage, and that you will continue braking once you release your brake levers as the callipers flex back to their original shape.

You're correct that you need to pull the cable further for the same braking force, but NOT that you need to pull it harder. It's basic physics - under braking there must be a moment and force equilibrium on the caliper and that equilibrium is not affected by the stiffness of the caliper, unless there is a large change in geometry: much larger than is actually seen.

The transition period that you refer to with the suspension is irrelevent: the final position is what matters. Any caliper has high enough damping and low enough mass that the transition period is essentially zero. Simially the brakes won't stick on due to a lack of stiffness in the calipers- By my rough calcs the natural frequency of a brake caliper will be in the order of kHz, therefore any variation in force will be of the order of milliseconds. There will be some hystereses but that will tend to give a lower force when releasing the brake levers compared to applying them.

If in any doubt sketch the deformed shape of the caliper. Now note that the deformed shape takes the pads further away from the rims when the brake levers are released (ei the cable goes back to the original length). To stick on they'd need to be closer

lawrences

Change your cables too.

taon24

Runtothehills wrote:

You're correct that you need to pull the cable further for the same braking force, but NOT that you need to pull it harder. It's basic physics - under braking there must be a moment and force equilibrium on the caliper and that equilibrium is not affected by the stiffness of the caliper, unless there is a large change in geometry: much larger than is actually seen.

The transition period that you refer to with the suspension is irrelevent: the final position is what matters. Any caliper has high enough damping and low enough mass that the transition period is essentially zero. Simially the brakes won't stick on due to a lack of stiffness in the calipers- By my rough calcs the natural frequency of a brake caliper will be in the order of kHz, therefore any variation in force will be of the order of milliseconds. There will be some hystereses but that will tend to give a lower force when releasing the brake levers compared to applying them.

If in any doubt sketch the deformed shape of the caliper. Now note that the deformed shape takes the pads further away from the rims when the brake levers are released (ei the cable goes back to the original length). To stick on they'd need to be closer

I meant harder in the more vague sense to pulling further in a shorter period of time, but accept that the force of the braking is equal once the callipers are on.

I also accept that the variation will be small, but that might be noticeable.

By my reckoning in three situations.
a) callipers open - cable pull force closes calliper (Nil rim resistance.)
b) calliper pads touch rim - cable pull force is now acting to generate two results, Movement of the calliper and force against rim - slight reduction in braking force during any flex of calliper.
c) brakes hard on - cable pull force equivalent to braking force (nil calliper movement.)

a) brakes hard on - cable released - callipers apply force against rims as they release their energy to come straight (braking continues as the callipers are unbending towards the rim). The movement of the callipers from bent to straight generates a force at the rim to resist the brake pads movement towards the centreline.
b) calliper pads just touch rim - callipers are straight with nil force to cause flexion.
c) callipers open - nil braking.

Sure, the flex of the callipers pushes the callipers further from the centreline during braking, but as you release the brakes, the brakes must first flex back to straight (brake pads don't move, while calliper does), maintaining force against the rim as they do so. It is inaccurate to suggest that the callipers spring open so rapidly that the flex of the callipers is resolved in the air.

Runtothehills

Ok I think we're on the same page now - though if you can notice the time taken for step b) in the loading process above I'll be impressed - the time period will be measured in milliseconds.

Not that flexy calipers aren't horrible - they are.

Also as a side point my comment about hysteresis doesn't depend upon how rapidly the calipers spring open. For any material the force-extension curve for loading will have higher forces for the same extension than the unloading curve. For most metals the difference is pretty low but for rubbers it can be significant.

jds_1981

I'm still waiting for a cheap road bike geometry disc brake frame to come along. Sod your silly road bike brakes.

Bar Shaker

Runtothehills wrote:

Bar Shaker wrote:

thescouselander wrote:

This is simply not possible - force cannot be absorbed as you describe. Yes the caliper is bending but the additional force you put into the caliper is still equally opposed by the rim against brake block once the caliper stops bending and the forces equalise. That is the force on the brake block / rim will still have increased even though the calliper bent slightly.

That is not the case if the arm is flexing.

Ask yourself about how force transfer to the pads would be affected if the caliper arms were:
1) more flexible
2) less flexible.

Think about how springs (flexible structures) store potential energy and then give this back when the force is removed. Is a flexible caliper arm storing potential energy, or transferring it to the pad?

The stiffness of the arms and the friction of the pads are both important factors.

Assuming the same lever arm and force in the cable the force transfer to the pad will be exactly the same. You might have to pull the brake lever further to get there (which is where the stored energy come in) but the force on the pad for a given force on the lever will not change. Force does not equal energy.

The stiffness of the arms will have an effect on the feel of the brakes but not the braking force.

Think about sitting on a bike with suspension (wrong forum but still), you will exert a certian force on the ground because of your weight. Now lock the suspension out and sit on the bike again - will that force change? Of course it won't, even though the system transferring the force of your weight to the ground (the bike) is a lot stiffer.

I am sorry but you are delusional. Let me put this into a simple exercise that you may be able to understand, with objects that you may have close to you in the office, or at school. Perhaps you have a clear plastic 12" (300mm) ruler. Hold one the bottom end between your thumb and index finger so that the ruler is vertical. Now push the top end sideways so it bends the ruler.

Repeat this exercise with a less flexible ruler, such as an engineering scale rule.

How does the force transfer to your finger and thumb?

Your comment above is that the flexibility makes no difference to the force that results but as we can see the stiffer ruler applies much more force for a given lateral load at the other end of the ruler.

Imagine if your caliper arms were made out of the same bendy plastic as your ruler. Would you be able to apply:
1) Less pad pressure
2) More pad pressure
3) The same amount of pad pressure a a forged alloy arm would apply

ednino

I've got Ultegra brakes, loads better than my old Tiagras. The Ultegra pads are still crap in the wet though

rolf_f

Bar Shaker wrote:

Imagine if your caliper arms were made out of the same bendy plastic as your ruler. Would you be able to apply:
1) Less pad pressure
2) More pad pressure
3) The same amount of pad pressure a a forged alloy arm would apply

Now imagine that you have two pairs of brake calipers - one with arms that are ever so slightly more bendy than the other pair.

Would you:

1) Pull the brake lever a few millimetres further to achieve the same pressure on the rims as you get with the less bendy arms?
2) Not pull the brake lever a few millimetres further and have less effective braking?

Analogies are fine but you have to keep them to the same magnitude as the point of interest or they end up misleading.