On 2019-03-15 07:08, wrote:
On Thursday, March 14, 2019 at 6:36:52 PM UTC-7, James wrote:
On 15/3/19 2:17 am, Frank Krygowski wrote:
On 3/13/2019 6:32 PM, Joerg wrote:
On 2019-03-12 11:13, AMuzi wrote:

How many new bicycles have drum brakes? Vanishingly few.


This was just meant as an example. Bicycles have largely
remained in the stone age, like chuck wagons where a chunk of
wood pressed against the steel ring of the wheels to brake. So
bicycles kind of skipped a technology.

Bikes didn't skip drum brake technology because bikes are
primitive. Only a very few bikes adopted drum brakes because that
technology wasn't optimum for bikes.

It's simplistic at best to pretend what's best for one
application is best for all applications. Every design choice
comes with benefits and detriments, and those are not the same
for a 4000 pound car as for a 20 pound bike.

Bicycle rim brakes have worked fine for over 99.999% users for
the past 100+ years. When mountain bikes came into fashion, some
off-roaders found a different set of benefits vs. detriments, and
discs made sense for them. But then fashion and marketing took
over, pushing discs toward road bikes.

Yes, we'll get a few testimonials here claiming discs are
"better." We get very few details on benefits vs. detriments.



For a while, the trend for road bikes was very narrow tyres pumped
up to very high pressure. 18 mm of tyre is pretty skinny.

Gradually the tyre width had become standard at 23 mm for road
bikes.

Now there is an emerging trend to ride wider tyres, with some
claiming much wider tyres are not only as fast but faster! I
suspect there is a diminishing return with wind resistance.

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. With a disc
brake I don't need to fiddle with the brakes regardless of tyre
width. That's a benefit.

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. Then you have to fix that or have rubbing
brakes. That doesn't happen with discs.

It is possible with hydraulic disc callipers to squeeze the brake
lever while the wheel is out, and then have trouble moving the pads
apart again to insert the wheel. That's a detriment, but doesn't
affect cable actuated disc brake callipers.

Hydraulic disc callipers are self adjusting like car hydraulic
disc callipers. Cable actuated disc callipers are not. Benefit
and detriment.

Hydraulic disc systems sometimes need bleeding. This requires
either a visit to a shop or a bit more kit ($30 - $50) for the home
maintenance person. Detriment. Probably not good if you are out
on a tour. Cables are probably more reliable. Cable operated discs
work fine, and there are also cable/hydraulic systems, where the
calliper is hydraulic and self adjusting, and actuated via a
cable.

Disc brake modulation is generally better. That is you can hold
the point of not quite skidding more easily. Benefit.

Disc brakes tend to work better in wet weather, or IOW, work the
same regardless of wet weather. Rim brakes rarely work as well
when the rims are wet.

Rim brakes on carbon fibre rims has never been a happy marriage,
but with disc brakes that problem is eliminated. Thus aerodynamic,
strong, stiff, light weight rims are now easier to manufacture and
use - made of carbon fibre.

Rim brakes do erode rims. Disc brakes do not. I guess the disc
rotor will wear out, but I'd rather replace a rotor than a rim.

It seems to me that many people try disc brakes and find few
drawbacks. That's just my opinion, unsubstantiated by statistics.

Are rim brakes good enough? Sure! They have been for a long time.
Are disc brakes better? Yes I think so. Not outstandingly, but
better. I'm not about to have my road bike modified to take disc
brakes, and I wouldn't let the choice of brakes on a new bike
dictate what I bought. YMMV.

-- JS
I took out the Colnago yesterday since I've been riding the cheaper
bikes with all the rain this year. I just put on a set of 25 mm
tubeless carbon rims with the Continental GP5000TL tires. Old person
with less than 400 miles and very little climbing so far this years
means that I'm am slower than frozen snot.

But I waited at the top for the group who started 5 minutes after me.
They caught me at the top. Rolling down the other side I could COAST
faster than the others could pedal. I started as tail end charley
because I assumed they would be a fast downhill as up. But I kept
overrunning the group and there was one out in front with a new
custom steel bike with a new 11 speed Ultegra. I accelerated to catch
him and then had to actually put the brakes on to keep from passing
him FAST. And then I was 4 bike lengths behind him and coasting most
of the rest of the way. When the road flattened out I had to only
pedal half the time. As soon as the road went up even a little I was
working a whole lot harder than he was.


How much do you weigh? I am around 220lbs and that, combined with a
steel frame, full tool set and other stuff in the panniers, makes me
pass almost everyone else on the downhill. On the uphill, not so much ...

Disc and rim brakes don't make a difference in that respect IME.

--
Regards, Joerg

http://www.analogconsultants.com/