Road Bike Brake Pad Problem - Little contact!

[willjohnsonuk]

Hi, to start off apologies if this is a newbie question, but i've looked all over and cant find an answer to my question anywhere..

I've just bought a mid-ish range road bike for the first time, and have a bit of a problem with the back brakes. They are caliper brakes, i have them adjusted and centered fine, so both pads DO contact the rim at the same time, and are not too close to the tyre or slipping off towards the spokes.

The problem is, the whole pad doesn't contact the rim, i dont have the bike with me so made a crude drawing on the computer:

This is the same on both sides (but not on the front brakes)

I understand back brakes are never as effective, but i know they should be more responsive than this, and probably shouldn't look like this either!

Is this something that will solve itself as the pads wear? Or is there a solution which im too stupid to see?

thanks!

 

[summerdays]

Depends which way the wheel is rotating in that image. You can toe in your brakes which helps to stop them squealing, as mentioned on this page. I do find that brand new pads don't stop quite as well immediately out of the packet.

 

[willjohnsonuk]

ah it may be the toe-in (wheel rotating to the right), as you can tell i dont know too much about bikes, after googling that it looks like what ive seen
also forgot to mention the bike is second hand (~100miles)
i think maybe i should just have a play about with cable tension etc to get them tuned properly

 

[bykeshed]

Toeing in of brake pads is common to help stop brake squeal. However, the toe should be minimal - half to 1mm max - otherwise you risk the rear end of the pad not making contact at all, reducing efficiency. Most pads are secured to the caliper with several washers and a nut. Two or more of the washers are bowl shaped, almost giving a ball joint effect, so the pads can be set at various angles. Pads are quite easy to adjust yourself if you have a little patience and time.

 

[willjohnsonuk]

thanks guys i will have a tinker once i am home, hopefully get it sorted! dont enjoy the feeling of "i hope i stop" haha

 

[Smokin Joe]

Orft the top o' me 'ead I'd say you've nothing to worry about, looks like the brakes have been set up by someone who knows what he (Or she, before The Claud starts spitting at me) is doing. From your sketch I assume it's the front of the brake block in contact first as it should be.

 

[MickeyBlueEyes]

I've never understood why 'toe-in' is seen as a fix. I'm not surprised that it reduces squeal as by setting the blocks up this way you've reduced the amount if contact on the rim, but, it's not fixing a problem it's putting a plaster over it. The 'toe' however will only last so long before it becomes parallel with your wheel and you then have to change your pads before the rear half has reached it's minimum depth. Surely if 'toe-in' were the way to have your pads set up then manufacturers would make them this way, i.e. thicker one side than the other. Pads are manufactured parallel, that's how they should function. If they squeal then something else is wrong.

 

[Dogtrousers]

I've never understood why 'toe-in' is seen as a fix. I'm not surprised that it reduces squeal as by setting the blocks up this way you've reduced the amount if contact on the rim, but, it's not fixing a problem it's putting a plaster over it. The 'toe' however will only last so long before it becomes parallel with your wheel and you then have to change your pads before the rear half has reached it's minimum depth. Surely if 'toe-in' were the way to have your pads set up then manufactures would make them this way, i.e. thicker one side than the other. Pads are manufactured parallel, that's how they should function. If they squeal then something else is wrong.

I'm glad you posted this because I've always thought this too.

I can see why applying the toe first will prevent the block from going into a kind of stick-slip situation which would result when the leading edge applied first. But like you I've always thought that once the pads have been used for a bit and worn they would end up presenting a parallel face to the rim.

Anyway, despite the above, I still toe in my pads when replacing them, by putting a cardboard shim between the rim and the pad, at the rear, then applying the brake and tightening the nuts so they are toed in. Because I don't have the courage of my convictions.

 

[MickeyBlueEyes]

Anyway, despite the above, I still toe in my pads when replacing them, by putting a cardboard shim between the rim and the pad, at the rear, then applying the brake and tightening the nuts so they are toed in. Because I don't have the courage of my convictions.

"I firmly believe its the wrong thing to do but I'll do it anyway"
Set up your pads level top to bottom, set them to run at the same radius as the centre of your braking surface, burn the cardboard and lose the toe. Go on, live a little

 

[Dogtrousers]

"I firmly believe its the wrong thing to do but I'll do it anyway"
Set up your pads level top to bottom, set them to run at the same radius as the centre of your braking surface, burn the cardboard and lose the toe. Go on, live a little

The god of brake blocks would punish me.

Makes me think of the following from Dylan Thomas I read somewhere of a shepherd who, when asked why he made, from within fairy rings, ritual observances to the moon to protect his flocks, replied: "I'd be a damn' fool if I didn't!"