Perhaps a slightly random subject to focus on, but it’s one I’ve been asked about a lot – or rather, as much as anything is one which is answered with a blank expression when mentioned.
What’s brake pad ‘toe-in’? It’s when the front of the brake pad touches the wheel rim before the rear.
Why bother with toe-in? Well, under the forces of forward momentum combined with the application of braking force from each side, the brake pads undergo a twisting motion. If you set your pads square against the wheel rim this twisting means the rear of the pad drags against the rim whilst the front of the pad is barely touching. This is what makes rim brakes squeal.
By toeing in you are basically setting up to account for the twisting forces. This not only improves your braking power (and thus bike control) but also eliminates that nasty squeal.
How? Easy. When adjusting your brake pads stick something thin behind the back of the pad – and only the very back edge. When I say “something thin” I’m talking a credit card, a half width of matchstick, flat elastic band or a folded puncture repair patch. If you have an old LeMond wedge then cut that up to brake pad width a slot it in between the pad and rim. Failing that or any of the other options above, use a Tacx brake shoe toeing tool. Yes, that really does exist!:
Once you have one of these objects in place adjust your pad so that it contacts the rim nice and squarely, front first leaving the gap offered by your object of choice at the rear of the pad. If you use the LeMond wedge or Tacx tool the just wedge that in place and push your pad up hard against it – wind on some cable tension and it’ll do the job for you meaning all you need to do is tighten the pad holder and you’re sorted.
One last tip: if you’re running Mavic Exalith rims, use a full matchstick width on new pads – after the first 500km you can then apply the methods above.
Get it? Got it? Good.