On 2017-10-13 08:50, wrote:
On Friday, October 13, 2017 at 8:15:57 AM UTC-7, Joerg wrote:
On 2017-10-12 09:26, jbeattie wrote:
On Thursday, October 12, 2017 at 7:36:15 AM UTC-7, Joerg wrote:
On 2017-10-11 18:16, jbeattie wrote:
On Wednesday, October 11, 2017 at 2:36:03 PM UTC-7, Joerg
wrote:
The adapters to increase rotor size in a post-post
situation (which I have front and back) look like this:

http://i.ebayimg.com/images/g/oK8AAO...Au/s-l1600.jpg

My MTB has a factory one from 160 to 180mm up front but I
am considering 203mm. That would make the thing even more
extreme, like this where the screws would look more
cattywompus or out of line than they already do:

https://i.ebayimg.com/images/g/w4MAA...bTa/s-l500.jpg

Why are the spacings so different on both sides while for
160mm their are not?

The angle of the caliper changes as you get into the larger
rotor sizes and thus the disparity.


Understood. This is also what Ralph wrote. However, many
calipers such as mine have round pads where it doesn't matter
if the angle is slighlty different.

I don't know your brakes, but the rotor might hit the internals
if the caliper is not angled correctly. You want the mechanism
following the arc of the rotor, which is what you will get with
your spacer.


It should also work with this spacer which avoids long screws:

https://erpimgs.idealhere.com/ImageF...963c864243.jpg



It moves the rotor out plus up so the angle should remain roughly
similar. Shimano has these as well but I just got an answer from
Jenson USA which carries them. They are flat and only 10mm (looks
less though) and my calipers need more "dive room" than that.

http://www.jensonusa.com/Shimano-F20...Z47&l=BR407Z47



So I'd need the bellied ones like in the link.


You also want to engage as much of the rotor as possible. I
don't think any of this is optional, is it? You just put in the
spacer, and you're done.


Just have to make sure it's the correct adapter. Adding a washer
here or there for fine tuning isn't a problem.

I'm still having this problem with why you would want disk brakes on
a road bike in California.


It is for my mountain bike. Currently it has 7" up front and 6" in back.
That is only borderline adequate for the loading and riding I do.
Yesterday I rode a trail where I taxed them a bit much again. I want to
upgrade both wheels to 8". Both are native 160mm and the front has an
adapter which I'd have to change out.

There is nothing that can replace brake power. Except more brake power.


... Extra weight, extra rolling resistance,
extra cost, far too much power the way it was and there is little
rain in California to worry about the slight delay in action between
a rim and disk brake.


In the winter it rains a lot up here in the Sierra foothills. There is
also a lot of standing water and creek crossings after which I
experience that dreaded 1-2sec "free fall" with rim brakes. Plus dirt
where I reach in and while getting some tepid brake response there is a
goose bump generating sandpaper noise.

So yes, if I ever need a new road bike I have two non-negotiable
requirements. Number one is disk brakes and number two is that the frame
must accept cyclocross-width tires. And must tolerate a serious rack.

--
Regards, Joerg

http://www.analogconsultants.com/