Getting brake block surface parallel with rim

[Brucey]

There is an excellent gadget available from TACX to set up brake blocks to align precisely with the rim, and to provide the very modest toe-in recommended....

that is an interesting gizmo but with a DP brake like that I would aim to set the left block slightly lower than the right block, which I would wager that gizmo does not do. The reason for this is that as the blocks wear, the left pad moves upwards, and the right block moves downwards. In the picture it looks as if, after comparatively little wear, the left block will be at risk of going into the tyre.

cheers

[Valbrona]

There is an excellent gadget available from TACX to set up brake blocks to align precisely with the rim, and to provide the very modest toe-in recommended....

that is an interesting gizmo but with a DP brake like that I would aim to set the left block slightly lower than the right block, which I would wager that gizmo does not do. The reason for this is that as the blocks wear, the left pad moves upwards, and the right block moves downwards. In the picture it looks as if, after comparatively little wear, the left block will be at risk of going into the tyre.

cheers

That's just because the gizmo isn't actually in the right position. It needs to go downwards a little so the inner lip engages with the very edge of the rim, which I am sure Rob knows, but it was just not in that position when the picture was taken.

I chucked my Tacx gizmo away. It can place the blocks too low on rims with a very narrow brake track, but it is okay for the vast majority of rims.

[Brucey]

am I right in thinking that the gizmo sets the brake blocks the same height each side? That was in good part my criticism of it, for DP brakes, anyway.

cheers

[Audax67]

I put a fine cable tie round the wheel, not too tightly, and position it at the rear of the blocks, then I put the brakes on and put a bit of Velcro round the lever to hold them. It's then simple to position the blocks and tighten them.

[GarethF]

+1 for the piece of card under the trailing edge of the new pad. Most new pads I've bought come in a special pack where you can tear off a piece for each side. Unfortunately if they need to be reset as the pads wear I have to use whatever is at hand in the garage, which is often course sandpaper and that seems to work ok too.

[PH]

There is an excellent gadget available from TACX to set up brake blocks to align precisely with the rim, and to provide the very modest toe-in recommended.



Rob

Is that on the right way?
They are a handy bit of kit (In the right hands)

[landsurfer]

Just someone put me right on this ...
Whatever angle I set the blocks at, toe in or out, will count for nothing after the first 30 miles as the block surface will wear parallel to the rim surface.
Or 10 miles in my case, I live on top of a big hill. And I'm heavy.
The angle of the block carrier will have no effect on the resultant friction co-efficient of the block after the parallel state is achieved ...
SO ... all the set up stuff does not matter as the blocks will wear in and find their own parallel state.
Get the blocks lined up vertically and in line with the rim and all will wear in ok ...
Therefore..... ?????
I've only been doing this for 40 years without a problem, or squealing brakes, so I may have missed something and need to buy a really "must have" tool to do the job..
Have fun, Stay safe..ish .

[Brucey]

they do wear so that the brake block surface is paralell to the rim when under braking load . Brake arms twist under load, and you don't know how much. The toe-in ensures that you don't get heel-first contact of the pad during bedding-in; this makes for an increased risk of a noisy, ineffective brake.

With many brakes you may well find that the 'worn-in' state is still very slightly toe-in because of caliper arm twist.

cheers

[PH]

Just someone put me right on this ...
Whatever angle I set the blocks at, toe in or out, will count for nothing after the first 30 miles as the block surface will wear parallel to the rim surface.
Or 10 miles in my case, I live on top of a big hill. And I'm heavy.
The angle of the block carrier will have no effect on the resultant friction co-efficient of the block after the parallel state is achieved ...
SO ... all the set up stuff does not matter as the blocks will wear in and find their own parallel state.
Get the blocks lined up vertically and in line with the rim and all will wear in ok ...
Therefore..... ?????
I've only been doing this for 40 years without a problem, or squealing brakes, so I may have missed something and need to buy a really "must have" tool to do the job..
Have fun, Stay safe..ish .

Get better brake blocks, mine remain toe in for a few hundred miles. And no one said it was a must have tool, just that it can be handy.

[robgul]

There is an excellent gadget available from TACX to set up brake blocks to align precisely with the rim, and to provide the very modest toe-in recommended.



Rob

Is that on the right way?
They are a handy bit of kit (In the right hands)

No it's not the right way round! - and it's a pic from Google, not my bike. The logo is a directional arrow off a circle ... just visible.

Rob

[PH]

Here's maybe a better image

[HKW]

Disadvantage with letting them wear in to the correct angle is that you need to throw them out prematurely? Over 40 years that must add up!

[Brucey]

maybe... but then again not all brake blocks cost the same, or wear the same rate, or wear the rims the same, or have a much thickness on them to wear. So it is just one factor amongst many.

cheers