Toed brake pads.... why toe in, not out?

[Dead Man]

Seems like such an elementary topic, but I was kinda shocked to learn that I've been doing this "backwards" for years.

Starting with a CX w/cantis years ago, I started toeing my brake pads. It instantly reduced squeak, seemed to improve braking, and I was convinced it reduced wear on pads and rim, by keeping them way cleaner. 'Cause I was toeing OUT, not in- The rear of the pad would wedge down onto the rim before the rest of the pad, thereby swiping the rim clean of grit and water before the full pad clamped down on the rim.

Couple weeks ago, I read somewhere... Park website? to angle in the FRONT/trailing edge of the pad. WTMF? So I googled some, and every thread/article/whatever I found also indicated the FRONT of the pad should be "toed in."

This seems crazy to me. Why would you want to essentially guide grit/mud/water into the brake contact area??

Could be my assumptions are all off.... It's happened before.

[benb]

It's not about grit...

When you're moving fast & you start applying the brakes hard the whole fork, posts, calipers, etc.. all flex. Assuming you're traveling forwards that will bend the brake pads in a way that toes them out.

By toeing them in they go parallel to the rim when everything starts flexing. Better braking & can prevent chatter.

[Wesley37]

Odd, at the Winterborne Bicycle Institute we were taught to toe-in the way you suggest, and we generally followed Barnett pretty closely (ie the published and reputable wisdom re: wrenching a bike)

[Mark McM]

Brake pads are actually inherently self-toeing, to some extent. As mentioned, the brake caliper arms, pad holders, etc., will flex under the force of braking, causing the pads to rotate slightly which tends to cause the lead edge of the pads (which is the rear of the pads) to press more firmly against the rim than the trailing edge (front of the pads). This uneven pressure will result in uneven wear, with the leading edge wearing more than the trailing edge - at least initially.

After some time, the initial uneven wear will help even out the pad pressure against the rim, so that subsequent wear will be more even. The final result will be that pad surface will be at a slight angle to the rim when the brakes are open, such that when the brakes are applied the calipers will flex so that the pads are parallel to the rim with an even pressure distribution across the pad.

This means that the regardless of the initial angle of the pads, they will wear down to this final surface angle. But until they wear into this final shape, there may be shuttering, squeeling, grabbing, or other affects. That is why install pads with a toe-in angle - so that pads start out close to the final wear angle, and break-in faster.

[Davist]

Interesting, the Kool Stop mt bike pads have an "ear" at the leading (back) edge for scraping off the mud/scree prior to braking, but you toe them "in" as well. The old Scott/Mathausers told you to use the cardboard of the package folded double as a toe in guide. I've always toed in..

http://media.nashbar.com/images/nashbar/products/500/KS-EDP-NCL-TOP.jpg

[Gummee]

If you're working on a hoopty and NOTHING but nothing will get the squeak out, toeing backwards is a good option to explore.

M