1987

I quite often see a extra aluminum washer fitted behind Campagnolos knurled washer called Rondella dentata on vintage bikes. But why? Off course if there is not enough room under the bottom head race and crown race. But usually it's and a extra washer there works against the intention of knureled washer to grabbing on to the brake caliper and the fork.

One of my bikes had this extra washer and it caused the front brake not recentering, so I removed the extra washer and now it works like it should.


Photo credit https://www.speedbicycles.ch

1987

Another example, but this time the extra washer against the brake caliper.


Photo credit https://www.speedbicycles.ch

rootboy 

That's an interesting question, 1987. Not that I can answer definitively but I just went and looked at my two Record-equipped bikes.
Both have the washer on the front, between the bolt boss and the crown. But, the fork crowns on my bikes have a curve to them so the washer, milled with a "concave" on one side, sits against the convex form of the fork crown, thus providing a flat surface for the toothed washer to sit. BTW, my front brake calipers both seem to center OK with this arrangement.

miamijim

3 reasons...

1. Flats. Campy's center bolt has 'flats', a cone wrench is used on the flats to hold the caliper in place while its tightened down. Without the extra spacer sometimes its next to impossible to get a wrench on the flats.

2. Clearance. sometimes the back edge of the brake pads will hit the fork blades thus preventing the caliper from opening all the way, a spacer solves that problem. I suppose thats the same as my 'flats' answer...it gives clearance for the wrench.

3. And of course rootboy's reason....to provide a flat surface for the toothed washer.

rootboy 

Right Jim,

and I really like my Park offset brake wrench for holding the flats.

1987

Good reasons

1. But you could hold the cone wrench from below. Mostly less comfortble but would work.

2. Never seen that, but that's what you have to do. If you don't do it like Richards Sachs, who cuts the pads.

3. Oh yes, forgot about that one. To obvious . The way the extra spacer should be used.

One solution I sometimes come across is two Rondella dentatas, a bit more exclusive but clever.

1987

Do you tighten them very hard?

Is it this wrench, Park Tool OBW-3?
https://www.parktool.com/product/offs...e-wrench-obw-3

rootboy 

Not sure what "very hard" means, 1987, but I tighten the rear nuts firmly, but not so tight the little flats wrench can't still center the caliper arms. My wrench is older I guess. It is OBW-1 which, apparently, they don't make anymore. A shame because with 10 mm on one end and 13 on the other , it's a very handy little tool. The OBW-4 might be a better choice now.

BTW, I can't use this wrench from underneath, with the wheel in place. And of course, you have to have the wheel in place.

1987

Thanks. I have probably been using some unorthodox methods for centering the break calipers. Will try yours next time.

What do you think about this new tool, Park Tool OBW-4?
https://www.parktool.com/product/offs...e-wrench-OBW-4

rootboy 

Yup. That OBW-4 is essentially the same as the OBW-1, but with two additional sizes added.

norskagent

I suppose you could eyeball the adjustment with the wheel in place, remove the wheel, make an estimated adjustment from underneath, replace wheel and check. Then repeat as necessary. Or just get the OBW.

Chombi

I use the appropriate number or thickness of washers to get the best fit of my calipers under the headset lower race for each of my bikes. If the one the caliper came with works, I use it, if if doesn't and things are getting too close or too far from each other, I find another one with a different thickness from all the extras I have from other caliper sets (French Brake makers usually supply a number of different ones with their brakesets) that will work. Thing is, the profile of forks from different brands of bikes are slightly different at the crown/brake mount area, and you will usually have to fiddle around with what washer thickness works with each bike.....

Chombi

1987

Thanks, I will tro to do it by the book next time. Noticed that Park Tool had a step by step tutorial:
https://www.parktool.com/blog/repair-...-brake-service

IthaDan 

Could the fork rake factor in? The washer could be a standoff to get the pads clamping onto the wheel on the proper side of "noon" so the pads are perpendicular to the caliper's arms?