Road Discs

On Monday, September 25, 2017 at 8:07:52 AM UTC-7, Frank Krygowski wrote:
On Monday, September 25, 2017 at 10:06:45 AM UTC-4, jbeattie wrote:

Cable discs can be better or worse than rim brakes in terms of stopping power and modulation. If you don't watch your pad adjustment and wear, you can find yourself with really bad braking -- like "oh, crap, man!" That happened to me on my way home from work, flying down a super-steep hill. I stopped (after a while) and adjusted the pads, and everything was AOK. Hydraulics adjust automatically. You can blow through pads on both and have to watch pad wear. My front hydraulics on the Roubaix were stopping me with NO pads -- I was stopping with the pad carriers. Ooops. Not so great on the rotors. Other downsides are complexity (bleeding hydraulic), dragging, pad break-in, adjustment for different wheels if any change in disc location. Wheel changes are a little more complicated, but then again, if you had fat tires and were trying to get them through calipers, that would slow you down more. If you have through axles, that can mean rack and work-stand incompatibility. There is a weight and aerodynamic penalty, which is meaningless for most people.

Regarding the fat tire issue: I think the logical comparison should be discs vs.
cantilever brakes (either classic ones or V-brakes), not discs vs. close clearance caliper brakes. ISTM most of the advantages of discs apply to
situations that _should_ lead to wider tires, ones that wouldn't fit through
most caliper brakes.

Disks are pretty much a requirement on a full suspension off-road bike. But putting this power on a bike that already has problems with too much braking is asking the question - why? Modulation? Yesterday I did a ride over a hill road where I hit 40 mph around a right angle turn. Calipers don't have enough modulation? I didn't even touch them.

On Monday, September 25, 2017 at 9:37:54 AM UTC-7, jbeattie wrote:
On Monday, September 25, 2017 at 8:48:58 AM UTC-7, Sir Ridesalot wrote:
On Monday, September 25, 2017 at 11:35:45 AM UTC-4, jbeattie wrote:
On Monday, September 25, 2017 at 7:55:26 AM UTC-7, Frank Krygowski wrote:
Snipped
I have tried some, which is why I'm concerned! Granted, I haven't done long
rides on any. My tests were on bikes belonging to friends, one bike I was
fixing for a bike tourist we were hosting, bikes I tested briefly while
helping a good friend shop for a new bike, and a mountain bike owned by an
acquaintance who let me ride it for maybe half an hour in our local forest
preserve.

The latter was the most upscale bike of the lot. When he traded bikes with me,
he cautioned me "Don't forget, you never need more than one finger on the
brakes." He was right, of course. And I'd be unlikely to forget on that
bike because it had undersized brake levers, plus it was way different than any
of my bikes. But on a road bike with normal sized levers, I'd worry about
forgetting.

I once saw a woman go over the bars because she wasn't familiar with the
reduced lever force of Shimano dual pivots, back when those were new technology.

It seems to me that stopping a bike hard should require a bit of a hard squeeze
on the levers. At least, until bicycles come with something vaguely akin to the
anti-lock brakes on cars. (Anti-pitchover brakes?)

I don't think front discs are a problem for most normal people coming from a dual pivot or other efficient brake. Rear hydraulic discs do require some adjustment because they are far more powerful than any cable operated brake, being that there aren't the usual losses from cable or housing. I was skidding my rear on the Roubaix, but that hasn't been an issue on the Norco for some reason. Maybe I'm acclimated -- or maybe the Roubaix had too much system pressure. The rear cable disc is no better than a rim brake in dry weather. A rear dual pivot is actually stronger, but I hope to remedy that problem with a new rear brake. The first generation Avid BB7s (mine are 13 years old) had crappy return springs that can't manage all the cable drag, and the caliper will rub after braking if the pads are set close to the disc.

-- Jay Beattie.

I can easily apply my front Dura Ace AX brake to a force where the rear wheel lifts a lot and I have to release the front brake lever to avoid going over the bar.

On my MTB with the roller cam rear brake under the chainstays, I can easily lock up the rear wheel in ant weather = dry or wet.

You can lock-up a rear wheel with basically any decent, well-adjusted brake. It's just a matter of effort at the lever. You need less effort to lock-up your rear wheel with a hydraulic disc, and the brake modulates differently -- braking force is delivered more quickly, particularly in wet weather.. Whether this is worth the price of admission is up to you.

In that case enjoy your .8 kg carbon fiber frame and fork with your 20 gram reduced brakeset. And then talk about modulation and add a disk brake set that weights in a kg more than the caliper.

On Monday, September 25, 2017 at 7:58:06 PM UTC+2, wrote:
On Monday, September 25, 2017 at 6:48:44 AM UTC-7, wrote:
On Monday, September 25, 2017 at 3:20:58 PM UTC+2, wrote:
On Monday, September 25, 2017 at 1:27:54 AM UTC-7, wrote:
On Sunday, September 24, 2017 at 11:16:25 PM UTC+2, wrote:
On Tuesday, September 19, 2017 at 2:11:36 PM UTC-7, Roger Merriman wrote:
jbeattie wrote:
So, my SuperSix was crushed in a roof-rack accident and last weak my
Roubaix was stolen out of the garage that I left open all night. I've
done that many times -- apparently one too many. I'm down to a gravel
bike and my commuter -- the reborn warranty CAADX (which is a great bike).

The gravel bike is a pig, but I'll use that for fall/winter/spring sport
riding. I want a fast bike, though -- and I've got a line on a nice bike
that I can get with rim brakes or discs, but the disc model will not be
available until December -- which really means that I get to ride it in
dry weather some time around May. I can get a rim brake model by the end of the month.

All the shops are pushing discs, and I did like the discs on the Roubaix
and on my gravel bike. I know this is absolutely the wrong group to ask
because it's wall-to-wall curmudgeons, but if you were buying your last
nice road bike, would you go rim brakes or discs? It will be a dry
weather bike or ridden in the rain only because of bad luck. There would
be no real weight penalty because the bike is so light to start with. I'm
not aero, so I don't care about the aero penalty with discs.

My concern with getting rim brakes is not really even a performance issue
because in dry weather, I've never had a problem with rim brakes -- but
to listen to the guys at the local shop, rim brakes are going the way of
the dodo. I'm worried about buying an antique!

-- Jay Beattie.









You will be able to get rim brakes and bits for them, I’d though though my
lifetime, I’m currently 42, my dad has managed to get some new tyres for
the NewHudson that they have for rolling along after grandchildren!

As a point of interest - the reason for disks is supposed to be stronger braking. And yet Campagnolo has just gone back from dual pivot back brake to single pivot because too many racers were locking the rear wheel up.


The real reason is weight, the rest is marketing BS.

A hydraulic disk has probably five times the stopping power.

Tom, really that is no problem for the majority of people. You can have an opinion about disk brakes, but one thing that almost everyone agree upon
is the positive feedback you get from disk brakes.

Lou, there is NO weight difference between the single and double pivot.

On 9/25/2017 5:09 PM, Doug Landau wrote:
On Monday, September 25, 2017 at 3:20:56 PM UTC-7, sms wrote:
On 9/25/2017 3:00 PM, jbeattie wrote:
On Monday, September 25, 2017 at 1:48:21 PM UTC-7, AMuzi wrote:
On 9/25/2017 2:23 PM, Frank Krygowski wrote:
On Monday, September 25, 2017 at 11:52:16 AM UTC-4, AMuzi wrote:
On 9/25/2017 9:59 AM, Frank Krygowski wrote:
On Monday, September 25, 2017 at 9:50:28 AM UTC-4, AMuzi wrote:

Uh, Tom, Super Record DP are 149 grams, the rear single
pivot caliper is 123 grams.

So, important to those cyclists who get outraged when the barista gives them
four quarters change instead of a dollar bill?


Aside from your opinion about which criteria other people
should find significant to their own riding, bike
manufacturers are relentless in demanding lighter weight
component sets from parts makers every season. There's more
than just caprice and vanity here.

I won't accuse the manufacturers of caprice and vanity. They're making
business decisions, both in how they choose to advertise and how they
choose to meet market demands - including those generated by their advertising.

But I will question the judgment of a customer who thinks 25 grams or so will
improve his riding experience in any significant way.

Not that I'm cynical or anything but a guy can only read so
many "carves through a turn like [latest trendy idiom]"
reviews.

We're left with the only quantifiable aspects of a new bike
purchase (real or 'enhanced truth'): weight and price.

Although, there are a lot of differences between bikes these days -- and particularly between rigid and suspended frames e.g. Domane and Roubaix. People are willing to accept the weight and aerodynamic penalty with discs, apparently on the belief that ordinary rim brakes are inadequate or because they want to use CF wheels. Who knows. We are in a real gizmo era, kind of like the late '70s and early '80s when we bought brakes that truly did not work. http://tinyurl.com/y79s3z4a But they were cool. We were much cooler back then, even if we couldn't stop

In the past two weeks I've seen one bicycle with a front drum brake, and
two with rod brakes. The front drum brake bicycle was one of the Chinese
bike share bicycles and it was in my office at City Hall, locked. The
hub is a drum brake/dynamo combination.

The brake is locked?

No, the bicycle is locked with the automatic nurse lock. I downloaded
the app and put in the bicycle number but it says that it's out of
service. I think the company delivered it for us to evaluate. Hard to do
so when it's locked up like that.

On Monday, September 25, 2017 at 3:20:56 PM UTC-7, sms wrote:
On 9/25/2017 3:00 PM, jbeattie wrote:
On Monday, September 25, 2017 at 1:48:21 PM UTC-7, AMuzi wrote:
On 9/25/2017 2:23 PM, Frank Krygowski wrote:
On Monday, September 25, 2017 at 11:52:16 AM UTC-4, AMuzi wrote:
On 9/25/2017 9:59 AM, Frank Krygowski wrote:
On Monday, September 25, 2017 at 9:50:28 AM UTC-4, AMuzi wrote:

Uh, Tom, Super Record DP are 149 grams, the rear single
pivot caliper is 123 grams.

So, important to those cyclists who get outraged when the barista gives them
four quarters change instead of a dollar bill?


Aside from your opinion about which criteria other people
should find significant to their own riding, bike
manufacturers are relentless in demanding lighter weight
component sets from parts makers every season. There's more
than just caprice and vanity here.

I won't accuse the manufacturers of caprice and vanity. They're making
business decisions, both in how they choose to advertise and how they
choose to meet market demands - including those generated by their advertising.

But I will question the judgment of a customer who thinks 25 grams or so will
improve his riding experience in any significant way.

Not that I'm cynical or anything but a guy can only read so
many "carves through a turn like [latest trendy idiom]"
reviews.

We're left with the only quantifiable aspects of a new bike
purchase (real or 'enhanced truth'): weight and price.

Although, there are a lot of differences between bikes these days -- and particularly between rigid and suspended frames e.g. Domane and Roubaix. People are willing to accept the weight and aerodynamic penalty with discs, apparently on the belief that ordinary rim brakes are inadequate or because they want to use CF wheels. Who knows. We are in a real gizmo era, kind of like the late '70s and early '80s when we bought brakes that truly did not work. http://tinyurl.com/y79s3z4a But they were cool. We were much cooler back then, even if we couldn't stop

In the past two weeks I've seen one bicycle with a front drum brake, and
two with rod brakes. The front drum brake bicycle was one of the Chinese
bike share bicycles and it was in my office at City Hall, locked. The
hub is a drum brake/dynamo combination.

Too bad I donated my old U brake mountain bike.


I see legions of drum brake bikes. https://www.biketownpdx.com/how-it-works/meet-the-bike I'm getting one for fast group rides! Nothing like a peppy shaft drive, metal basket and a drum brake.

-- Jay Beattie.

On Mon, 25 Sep 2017 08:48:53 -0700 (PDT), Sir Ridesalot
wrote:

On Monday, September 25, 2017 at 11:35:45 AM UTC-4, jbeattie wrote:
On Monday, September 25, 2017 at 7:55:26 AM UTC-7, Frank Krygowski wrote:
Snipped
I have tried some, which is why I'm concerned! Granted, I haven't done long
rides on any. My tests were on bikes belonging to friends, one bike I was
fixing for a bike tourist we were hosting, bikes I tested briefly while
helping a good friend shop for a new bike, and a mountain bike owned by an
acquaintance who let me ride it for maybe half an hour in our local forest
preserve.

The latter was the most upscale bike of the lot. When he traded bikes with me,
he cautioned me "Don't forget, you never need more than one finger on the
brakes." He was right, of course. And I'd be unlikely to forget on that
bike because it had undersized brake levers, plus it was way different than any
of my bikes. But on a road bike with normal sized levers, I'd worry about
forgetting.

I once saw a woman go over the bars because she wasn't familiar with the
reduced lever force of Shimano dual pivots, back when those were new technology.

It seems to me that stopping a bike hard should require a bit of a hard squeeze
on the levers. At least, until bicycles come with something vaguely akin to the
anti-lock brakes on cars. (Anti-pitchover brakes?)

I don't think front discs are a problem for most normal people coming from a dual pivot or other efficient brake. Rear hydraulic discs do require some adjustment because they are far more powerful than any cable operated brake, being that there aren't the usual losses from cable or housing. I was skidding my rear on the Roubaix, but that hasn't been an issue on the Norco for some reason. Maybe I'm acclimated -- or maybe the Roubaix had too much system pressure. The rear cable disc is no better than a rim brake in dry weather. A rear dual pivot is actually stronger, but I hope to remedy that problem with a new rear brake. The first generation Avid BB7s (mine are 13 years old) had crappy return springs that can't manage all the cable drag, and the caliper will rub after braking if the pads are set close to the disc.

-- Jay Beattie.

I can easily apply my front Dura Ace AX brake to a force where the rear wheel lifts a lot and I have to release the front brake lever to avoid going over the bar.

On my MTB with the roller cam rear brake under the chainstays, I can easily lock up the rear wheel in ant weather = dry or wet.

Cheers

Given that the braking force of a wheeled vehicle is a factor of the
coefficient of friction between the tires and the road I am at a bit
of a loss as to why a disk brake is so much superior to a rim brake as
with vee brakes I can easily skid either the front wheel (very
carefully :-) or the rear wheel, or both wheels together on ordinary
black asphalt pavement, either dry or wet, using two fingers on the
brake lever.

Will disk brakes somehow magically improve this.
--
Cheers,

John B.

On Mon, 25 Sep 2017 11:15:20 -0700 (PDT), wrote:

On Monday, September 25, 2017 at 9:37:54 AM UTC-7, jbeattie wrote:
On Monday, September 25, 2017 at 8:48:58 AM UTC-7, Sir Ridesalot wrote:
On Monday, September 25, 2017 at 11:35:45 AM UTC-4, jbeattie wrote:
On Monday, September 25, 2017 at 7:55:26 AM UTC-7, Frank Krygowski wrote:
Snipped
I have tried some, which is why I'm concerned! Granted, I haven't done long
rides on any. My tests were on bikes belonging to friends, one bike I was
fixing for a bike tourist we were hosting, bikes I tested briefly while
helping a good friend shop for a new bike, and a mountain bike owned by an
acquaintance who let me ride it for maybe half an hour in our local forest
preserve.

The latter was the most upscale bike of the lot. When he traded bikes with me,
he cautioned me "Don't forget, you never need more than one finger on the
brakes." He was right, of course. And I'd be unlikely to forget on that
bike because it had undersized brake levers, plus it was way different than any
of my bikes. But on a road bike with normal sized levers, I'd worry about
forgetting.

I once saw a woman go over the bars because she wasn't familiar with the
reduced lever force of Shimano dual pivots, back when those were new technology.

It seems to me that stopping a bike hard should require a bit of a hard squeeze
on the levers. At least, until bicycles come with something vaguely akin to the
anti-lock brakes on cars. (Anti-pitchover brakes?)

I don't think front discs are a problem for most normal people coming from a dual pivot or other efficient brake. Rear hydraulic discs do require some adjustment because they are far more powerful than any cable operated brake, being that there aren't the usual losses from cable or housing. I was skidding my rear on the Roubaix, but that hasn't been an issue on the Norco for some reason. Maybe I'm acclimated -- or maybe the Roubaix had too much system pressure. The rear cable disc is no better than a rim brake in dry weather. A rear dual pivot is actually stronger, but I hope to remedy that problem with a new rear brake. The first generation Avid BB7s (mine are 13 years old) had crappy return springs that can't manage all the cable drag, and the caliper will rub after braking if the pads are set close to the disc.

-- Jay Beattie.

I can easily apply my front Dura Ace AX brake to a force where the rear wheel lifts a lot and I have to release the front brake lever to avoid going over the bar.

On my MTB with the roller cam rear brake under the chainstays, I can easily lock up the rear wheel in ant weather = dry or wet.

You can lock-up a rear wheel with basically any decent, well-adjusted brake. It's just a matter of effort at the lever. You need less effort to lock-up your rear wheel with a hydraulic disc, and the brake modulates differently -- braking force is delivered more quickly, particularly in wet weather. Whether this is worth the price of admission is up to you.

In that case enjoy your .8 kg carbon fiber frame and fork with your 20 gram reduced brakeset. And then talk about modulation and add a disk brake set that weights in a kg more than the caliper.

You don't understand Tom. It is NEW, it is DIFFERENT! and for those
reasons it must be BETTER.

--
Cheers,

John B.

On 9/25/2017 6:00 PM, jbeattie wrote:
People are willing to accept the weight and aerodynamic penalty with discs, apparently on the belief that ordinary rim brakes are inadequate or because they want to use CF wheels. Who knows.

Many people are willing to accept anything that's in fashion in their
own little world. Fashion is amazingly powerful, and doesn't need to
make any particular sense.

At least we can claim that disc brakes are marginally more useful than
tattoos.

--
- Frank Krygowski

On Mon, 25 Sep 2017 23:06:43 -0400, Frank Krygowski
wrote:

On 9/25/2017 6:00 PM, jbeattie wrote:
People are willing to accept the weight and aerodynamic penalty with discs, apparently on the belief that ordinary rim brakes are inadequate or because they want to use CF wheels. Who knows.

Many people are willing to accept anything that's in fashion in their
own little world. Fashion is amazingly powerful, and doesn't need to
make any particular sense.

At least we can claim that disc brakes are marginally more useful than
tattoos.


I'm not sure of that. Down tha pub in your wife beater showing your
"sleeves" makes you a lot more impressive then if you come in the door
with a disk brake under your arm :-)
http://tinyurl.com/y79f4md9

Just like your $449.00 Road Glasses makes you a far better cyclist
than some old fellow wearing a pair of $6.00 safety glasses :-)
http://tinyurl.com/y9wq8ceq
--
Cheers,

John B.

On 26/09/17 13:06, Frank Krygowski wrote:
On 9/25/2017 6:00 PM, jbeattie wrote:
People are willing to accept the weight and aerodynamic penalty with
discs, apparently on the belief that ordinary rim brakes are
inadequate or because they want to use CF wheels. Who knows.

Many people are willing to accept anything that's in fashion in their
own little world. Fashion is amazingly powerful, and doesn't need to
make any particular sense.

At least we can claim that disc brakes are marginally more useful than
tattoos.


If a person wants to use wheels with CFRP rims, a bike with disc brakes
makes sense.

CFRP rims with rim brakes usually work ok in dry conditions provided the
correct brake blocks are used. Some CFRP rims can be damaged if the
wrong pads are used, and some have been damaged even with the "correct"
pads.

But in wet conditions, the braking performance is generally very much worse.

Disc brakes solve those problems, and allow rim manufacturers to save
more grams because there's no need for a braking surface.

--
JS