On 19/3/19 6:32 am, Joerg wrote:
On 2019-03-14 18:36, James wrote:

Now I use a 25 mm rear tyre (that measures 27 mm), and to remove the
wheel I must release the brake lever (Campagnolo) or deflate the tyre.
With a 23 mm tyre I don't need to do that.Â* With a disc brake I don't
need to fiddle with the brakes regardless of tyre width.Â* That's a
benefit.


That I don't understand. Even the early 80's Shimano 600 set on my road
bike has little release handles on each caliper to get out a 25mm+ wheel
with lots of room to spare.


The Campagnolo calipers on my bike don't have a quick release, but there
is a button on the lever that has the same effect.


In fact sometimes when you go to shove a wheel in with rim brakes and
centre or dual pivot callipers, you can catch the calliper and move it
from centred.Â* Then you have to fix that or have rubbing brakes. That
doesn't happen with discs.


Though a disc does get bent easily and you have to pay more attention
when re-installing a wheel. Fixing is easy as well as long as you do not
touch the disc with bare hands.


I haven't tried bending a disc, but it doesn't look easy to me. You
must be very rough.


Hydraulic disc callipers are self adjusting like car hydraulic disc
callipers. ...


Ahm, sort of. The reservoirs are typically a bit small to accommodate
all the wear. I have to top off with DOT-4 at times which is nasty stuff
when it gets onto clothes and things.


Shimano hydraulics use mineral oil. Not nasty like some other brands.


Â*Cable actuated disc callipers are not.Â* Benefit and detriment.


Cable calipers are very easy to adjust, just turn a knurled trim knob. A
downside of many is that they only have one moving piston while the
opposite piston is fixed. The rotor flexes to the side every time you
brake. Beats me why they design them that way.


"Some mechanical disc brakes, such as the TRP Spyre, work by pushing
both brake pads simultaneously against the rotor. "

https://cyclingtips.com/2018/05/complete-faq-to-road-disc-brakes/

And for Frank, "Disc brakes have been around on bicycles for a decent
amount of time – as early as the 50s, in fact."

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JS