Cycling UK Forum

Brucey wrote:

Mick F wrote:Nowt to do with the spring.

Everything to do with the spring....

It's NOTHING to do with the spring.

Take the spring off and the brake will still be centred and operate, though floppily of course and rub a bit.
The spring is a release spring and gives "feel" to the brake lever.

Mick F wrote:

Brucey wrote:

Mick F wrote:Nowt to do with the spring.

Everything to do with the spring....

It's NOTHING to do with the spring.

Take the spring off and the brake will still be centred and operate, though floppily of course and rub a bit.
The spring is a release spring and gives "feel" to the brake lever.

The spring is what keeps the blocks off the rims when you are not pressing the lever, isn't it? I would expect that a calliper without its spring would still slow / stop the bike when you needed it, but the rest of the time the blocks would scrape the rims and the whole assembly would rattle.

FWIW, Mick, Brucey, I think you are both right. Just not completely right.

And now for something calming and pleasant.

pwa wrote:The spring is what keeps the blocks off the rims when you are not pressing the lever, isn't it?

That's exactly what it's for.
Return spring.

Just done an experiment with Mercian.
Rear brake is single pivot.

Bike on the stand.
Unlatched the spring on both sides so it was free do as it pleased ............. and the brake works just as well as before and remains properly centred. It doesn't release very well of course, but the wheel spun fine.

Because the brake levers are Ergos, the brake lever returns ok by dint of the gear shift paddle being sprung-loaded forwards.

I say again.........
Single pivot brakes are centred by the centre bolt. If the brake is uneven and won't pull the same on both sides, it'll be the cable restricting it. Trial and error will sort it.

Doing it without the spring is a good experiment. I must try that again sometime when and if I need to set up a single pivot brake again.

Hi,

Mick F wrote:

Brucey wrote:

Mick F wrote:Nowt to do with the spring.

Everything to do with the spring....

It's NOTHING to do with the spring.

Take the spring off and the brake will still be centred and operate, though floppily of course and rub a bit.
The spring is a release spring and gives "feel" to the brake lever.

It's common sense to have a spring on brakes and you would call it a return spring so the brakes don't rub on the inside of your drums on your car

.......... except disc brakes.
They rub (gently) all the time as there's no return spring.

Hi,

Mick F wrote:.......... except disc brakes.
They rub (gently) all the time as there's no return spring.

Piston seals.........They are designed to return the piston just clear of the disc to prevent rubbing.

I can confirm 2 centring tools for 500 and 605, I have one of each.

Spindles aren't Alloy on my 405/605's , I know because I have had them to bits to extend the threaded bit at the back for use on the trike.

Can't comment on Carrera , never messed with one but allot through bold does seem unlikely to me.

Sorry, wasn’t referring to the pivot being alloy, just the arms. Hence reference to the spongy feel.

I spent happy hours as a teenager, bending the springs on Weinmann 500s and 730s, to get them to centre properly. I gradually got better at tightening different bits in the right sequence instead, but it was still tricky. I have one of those Weinmann tools in my box, from the last such brakes I ever had.

Braking is strange. I got some Universals, then fairly soon went on to some Mark II Dura Ace models on my road bike. They stayed till I got some of the last SP Athenas.

When I first got the Dura Ace calipers, I nearly went over the bars first time, because they were so effective. But I finally replaced them with Shimano DPs because they were the opposite. That was on a different bike, could have been MA I suppose (see another thread) because the shoes were a bit lower, but not much. Maybe that's what they call brake fade

NATURAL ANKLING wrote:Hi,

Mick F wrote:.......... except disc brakes.
They rub (gently) all the time as there's no return spring.

Piston seals.........They are designed to return the piston just clear of the disc to prevent rubbing.

Disc runout (there's always some, even if it's 0.05mm) does this too, or in place of a retracting seal.

The late Jobst Brandt worked on disc brakes for Porsche and it was a major breakthrough when they realised it added virtually no drag if the pads touched the disc without any force. Prior to this, all sorts of fancy retraction mechanisms were tried. However, even a tiny amount of drag is unacceptable on a bicycle, with a fraction of the power to waste.

Mick F wrote:

Brucey wrote:

Mick F wrote:Nowt to do with the spring.

Everything to do with the spring....

It's NOTHING to do with the spring.

Take the spring off and the brake will still be centred and operate, though floppily of course and rub a bit.
The spring is a release spring and gives "feel" to the brake lever.

Nonsense.

Moving the centrebolt only affects the brake centring because it moves the spring.

By your logic you would park a car with a bomb in it and when the bomb blew up, you would blame it on the car, not the bomb....

Try unhooking one side of the spring and see how you get on....

[BTW in case it isn't b-obvious to you (like it should be) once the spring is unhooked from both sides of a SP brake, you can twirl the centrebolt into any position you like.]

Hi,

peetee wrote:FWIW, Mick, Brucey, I think you are both right. Just not completely right.

And now for something calming and pleasant.
5CFBD2A0-C0D6-4DFF-8F80-95FA5EAE459B.jpeg

Where's the cows

Brucey wrote:

Mick F wrote:

Brucey wrote:

Everything to do with the spring....

It's NOTHING to do with the spring.

Take the spring off and the brake will still be centred and operate, though floppily of course and rub a bit.
The spring is a release spring and gives "feel" to the brake lever.

Nonsense.

Moving the centrebolt only affects the brake centring because it moves the spring.

Try unhooking one side of the spring and see how you get on....

[BTW in case it isn't b-obvious to you (like it should be) once the spring is unhooked from both sides of a SP brake, you can twirl the centrebolt into any position you like.]

So, you're agreeing with me as well as disagreeing!

The centring of the brake is by dint of how its mounted.
The spring has to be the same on both sides to stop it being off-centre ............. of course!
Remove the spring, and the brake is still centred.

Try it.
I have, and what I say it true.

Hi,
So there