Trouble adjusting brake pads - advice please.

[swayzak]

Hi

After 9 months or so, it was time to change my Swissstop Blue pads for my Thorne Sterling Shimano LX V brakes.

However I can't seem to adjust them perfectly.

The back pads rub, and it appears that at least one of them is kind of toed in towards the rear e.g even though there is plenty of clearance at the front of the pad, the rear tip seems to catch on the rim.

So I have to have the pads further away from the rim than necessary to minimise the rub.

Is there an easy way to make the pads more parallel to the rim ?

The rub seems to be only at certain parts of the rotation - so maybe the wheel needs truing ?


thanks

It also only seems to catch

[julk]

The adjustment is usually done by loosening the nut holding the brake pad and moving it around until the pad faces the way you want.

I temporarily put a piece of cardboard under the trailing edge of the pad and holding the pad against the rim, tighten the nut up. This gives a bit of toe in which usually avoids brake squeal.

If the brake pad needs to be nearer to, or further from, the rim then swap the thick and thin washers over whilst the nut is off.

If none of this makes sense, then post again and I will put some photos up.

And yes the wheel needs to be true for the best results.

[swayzak]

Thanks.

The adjustment is usually done by loosening the nut holding the brake pad and moving it around until the pad faces the way you want

Does it matter where they sit in the vertical plane e.g. closer to tyre or centre of rim ?

If the brake pad needs to be nearer to, or further from, the rim then swap the thick and thin washers over whilst the nut is off

I've been adjusting this by altering cable slack and/or adjusting spring screw for altering distance of pad from rim. Is this incorrect ?

[julk]

I try to get mine in the centre of the rim, the only thing that really matters is for it to hit the rim and not touch the tyre.

Altering cable slack is fine for small cable adjustments, v-brake arm spring adjustment is good for centering the pads so each arm moves the same distance.
Swapping thin/thick washers over would be for a bigger adjustment which the cable cannot give without being pulled through and reclamped or maybe when fitting new pads.

Whatever works for you is correct, there are just some choices available.

[expr]

sometimes it is also easier as julk has suggested to put a small shim / cardboard at the leading edge of the pad but use the brake lever then to apply the pressure to the brake arms while the pad nut is tightened up.

The one thing to make sure of is the correct installation of the concave and convex washers which creates a ball joint effect. If this is incorrect it will allmost allways never allow the correct movement of the joint.

To centre the pads so that equal distance from pad to rim is the same both sides you should use the adjusting screw that alters the spring tension on the arm usually a small philips head screw.

[swayzak]

sometimes it is also easier as julk has suggested to put a small shim / cardboard at the leading edge of the pad but use the brake lever then to apply the pressure to the brake arms while the pad nut is tightened up.

Thanks

But do you mean trailing edge (to create a toe-in anteriorly) or leading edge (for posterior toe-in) ?

[julk]

I have the blocks just a fraction nearer to the rim at the front of the bike.
The rotation of the wheel then closes the gap for you as the block grips and the brake flexes.
I find this makes for the quietest braking.

[expr]

Swayzak,

my apologies, yes I do mean at the trailing edge just having a pre senior moment I think. sorry for the confusion!

[swayzak]

Wouldn't toeing-in eventually need redoing, as the tendency with braking would be for the pad/rim to flatten against each other & therefore remove the angle between the 2 surfaces ?

[Erudin]

The way I install new v-blocks is to unscrew the cable adjuster bolts on the lever almost fully (or use a toe-strap/velcro watch strap to apply brake lever) then set the pads onto the rims and tighten, then screw the adjuster bolt back in (or remove strap) until pads are clearing rims sufficiently.

http://bicycletutor.com/adjust-v-brakes/

[julk]

Wouldn't toeing-in eventually need redoing, as the tendency with braking would be for the pad/rim to flatten against each other & therefore remove the angle between the 2 surfaces ?

Yes, eventually, but it takes a long time.
The pads wear evenly because the brake flex is just enough to put the pads flat on the rim under braking pressure.
You do need something to maintain on a Thorn Rohloff, they are just too reliable and you would get bored otherwise

[PH]

There's a little tool to help get the adjustment spot on, it isn't essential, it just makes it easier and quicker.
http://www.bikeradar.com/gear/category/tools/cycling-tools/brake-toe-in-tool/product/brake-shoe-tuner-19005