I have a bike here with Avid BB7s-Road disc brakes. In trying to align the brake bodies with the rotors I notice that the spherical washers which are supposed to be on the mounting bolts (and allow precise angle alignment) are missing.

The pictures below show the difference.



The alignment is pretty close even without the washers; but there will be some uneven pad wear.

Big deal or not?

Bonus question--what size disc will these brakes handle? It looks to me as though the disc is too small; and the pads are not getting as big a bite as they are supposed to.

As always, thank you!

I sure hope you plan to do the right thing and not pass that bike back as "fixed" until you advise the owner that their brakes are seriously compromised. Those washers are vital to the brake design.

Yep, without them the pads won't be in the correct position over the rotor, the pads won't be using the outer 5mm of the rotor and they'll be rubbing on the rotor arms.

Without those washers the outer edge of the rotor must nearly be hitting the caliper.

Actually it's the reverse situation, where the disc does not extend far enough into the caliper, which led to my bonus question in the OP.

Actually I've already called it to his attention, although I need to stress that it is apparently a more serious problem than I initially thought.

What I like to do in cases like this is just pass along the link to this thread and let the owner read the experts' opinions for himself.

What a great resource this is!

The incorrect adapter must be on the bike.

What size rotor is being used?

Adapters need to match rotor size and you need to take into account what size brake mounts are on the bike.

Post a size on photo of the brake setup.

Pads overhanging the rotor will get a step worn into them and this could lead to brake failure.

I am not an expert, nor do I play one on the internet. Though, it is obvious that someone has been playing mechanic on this bike. (Not you, of course.)

Lavish photo spread will be posted in an hour or so, stay tuned!!!!!

The washers are a convex-concave pair.. made by the Many Millions and used on all V brake Brake shoes in pairs on either side of the brake arm..


The alignment using them on the Post mount bolts is super simple ... with the bolts a bit Loose You hold the brake lever , so the pads grip the rim.

and while still holding the brakes on You tighten the 2 bolts on the caliper.

on the V brake pad set there is a thicker and thinner concave faces washer that will offer a bit of radial adjustment when screwing into your adapter

of the size for the disc chosen.

same adapter functions with the next larger disc size on the front than the rear ..
and will usually be marked as such .

140/160; 160/180; 180/210 ..

Hate to report that i have seen bike shops do this before. Even seen customers bikes with the spherical stack located on top of the caliper which causes the same.
Easy fix but certainly needs to be addressed.

I'm guessing this setup will be a 140mm rotor with a 160mm adapter and the CPS washers were removed in an attempt to get more pad / rotor contact.

Some setups require these washers on top.

https://si.shimano.com/php/download.p...0A-001-ENG.pdf

With that adapter, the underside of the bolt heads aren't parallel with the top of the caliper, these washers allow the bolt heads to properly tighten down on the caliper.

The photo of the pads that I posted earlier were from a incorrectly setup Shimano brake which had the washers placed underneath the caliper.



* Only Avid brakes require these washers on the underside of them and Avid now makes 'standard' brake calipers that don't require these washers anymore except in a similar setup to what's in that Shimano document.

Currently the installed rotors are 140 rear and 160 front
Installed adapters are marked F180/R160



Sooooo, as I understand it so far, the bike needs
new rear brake wire
new rearmost section of brake cable housing
new washer setups for all 4 caliper attachment bolts
new larger disks for front and rear, OR new adaptors in size F160/R140
and . . . . . ..?

As you can tell, this is not my area of expertise. Owner brought me the wheel for truing and you know how one thing leads to another . . .

I would get the proper mounts rather than swap the rotors;those are plenty big for that bike.



Your client is going to die. When he doesn't close his skewer,it's going to go into the rotor and the bike will catch fire and explode. Unfortunately,this isn't a Trek,so all you can do is move the skewer lever to the right side. Preferably behind the fork leg.

New adapters & washers would be the cheaper option.

I don't like the way that front qr skewer looks either.

Situation's handled, customer's happy, I'm happy, bike is happy. Thanks, Guys!

A round of squeals. Wheee!

The one word answer to BB7 problems, is Shimano!