Wider tires, All-road bikes

Frank Krygowski wrote:
On 1/27/2019 8:21 PM, Roger Merriman wrote:
wrote:
On Sunday, January 27, 2019 at 3:43:22 AM UTC-8, Roger Merriman wrote:
Tom Evans wrote:
On 25/01/2019 00:19, Mark J. wrote:

I've been tempted to buy a cheap fat bike for the novelty; I expect it
would handle like a tank.


I got a cheap adventure (like a cross) bike, 40mm tyre, as a stopgap
when my normal road bike was out of action for a few weeks.

The results were very surprising. The geometries were the same, the tyre
rolling resistance didn't appear to be much different and the extra 4kg
didn't appear to make much difference to my speed.

On the plus size it was a more comfortable to ride, it felt slightly
more solid on the road.

I now ride it all the time in preference to my road bike.




Few years back I bought a cheap but relaxed CX bike pre adventure bikes
etc, it had its issues mainly it’s brakes which where canti and couldn’t
cope with being used like a MTB lite, it’s weight I generally didn’t
notice, I even took it up Mt Teide

I replaced it last year with a adventure bike, which main advantages are
better brakes cable disk vs canti and 2/9 vs 3/7 gearing.

It is my road bike, I do tend to run CX sized tyres as generally is more
choice and to give mud clearance. But I do notice how it rides bumps and
frankly is much more grip, some will be the type of tyres, some the size.

I don’t appear to be any slower, checking my times. Any differences are
marginal.

Roger Merriman

I had exactly the same problem with my Ridley XBow. Then I bought a set
of TRP 9.0 V-brakes and all of the stopping problems disappeared.

On my Redline Conquest I fitted Avid hydraulic disks and the braking was
WAY too strong. So strong that it is difficult to modulate it. I would
suspect that if I were doing it again I would use those tiny diameter road bike disks.


I assume they where mini Vs? Either way in the end though I used posh pads
to improve the brakes, I was unconvinced that there would be much
improvement for my use, ie MTB lite in many cases.

I’ve never yet had a Hydro system that was too powerful, don’t get me wrong
the play MTB has far more powerful brakes than the old Commute beast, so I
if I forget it’s a bit of surprise how much bite, how quickly but you adapt
quickly.

My worry about touchy brakes is about reflex action in a true emergency
situation. I've written about the time I was on a 30mph downhill and a
couple deer walked out of the woods. It was the hardest braking I'd ever
done at high speed, and I feel lucky to not have crashed.

I was on a bike I've ridden for over 30 years. I modulated the
cantilever brakes perfectly. But I think if I had new discs with low
hand effort, I'd almost certainly have locked them up and gone down hard.

Granted, such an experience is extremely rare for me. But I'd still like
all my bikes to require roughly the same amount of brake lever force.



You’d think it would be so, but really quite differing brakes don’t seem to
cause confusion. I will admit that first time I use the MTB with is 180mm
etc disks they are so instant, but actually you don’t lock, it’s a very
easy system to use to it’s full, ie tyres at the point of locking but not
quite etc.

Roger Merriman

On Tuesday, January 29, 2019 at 6:07:16 AM UTC-8, Roger Merriman wrote:
Frank Krygowski wrote:
On 1/27/2019 8:21 PM, Roger Merriman wrote:
wrote:
On Sunday, January 27, 2019 at 3:43:22 AM UTC-8, Roger Merriman wrote:
Tom Evans wrote:
On 25/01/2019 00:19, Mark J. wrote:

I've been tempted to buy a cheap fat bike for the novelty; I expect it
would handle like a tank.


I got a cheap adventure (like a cross) bike, 40mm tyre, as a stopgap
when my normal road bike was out of action for a few weeks.

The results were very surprising. The geometries were the same, the tyre
rolling resistance didn't appear to be much different and the extra 4kg
didn't appear to make much difference to my speed.

On the plus size it was a more comfortable to ride, it felt slightly
more solid on the road.

I now ride it all the time in preference to my road bike.




Few years back I bought a cheap but relaxed CX bike pre adventure bikes
etc, it had its issues mainly it’s brakes which where canti and couldn’t
cope with being used like a MTB lite, it’s weight I generally didn’t
notice, I even took it up Mt Teide

I replaced it last year with a adventure bike, which main advantages are
better brakes cable disk vs canti and 2/9 vs 3/7 gearing.

It is my road bike, I do tend to run CX sized tyres as generally is more
choice and to give mud clearance. But I do notice how it rides bumps and
frankly is much more grip, some will be the type of tyres, some the size.

I don’t appear to be any slower, checking my times. Any differences are
marginal.

Roger Merriman

I had exactly the same problem with my Ridley XBow. Then I bought a set
of TRP 9.0 V-brakes and all of the stopping problems disappeared.

On my Redline Conquest I fitted Avid hydraulic disks and the braking was
WAY too strong. So strong that it is difficult to modulate it. I would
suspect that if I were doing it again I would use those tiny diameter road bike disks.


I assume they where mini Vs? Either way in the end though I used posh pads
to improve the brakes, I was unconvinced that there would be much
improvement for my use, ie MTB lite in many cases.

I’ve never yet had a Hydro system that was too powerful, don’t get me wrong
the play MTB has far more powerful brakes than the old Commute beast, so I
if I forget it’s a bit of surprise how much bite, how quickly but you adapt
quickly.

My worry about touchy brakes is about reflex action in a true emergency
situation. I've written about the time I was on a 30mph downhill and a
couple deer walked out of the woods. It was the hardest braking I'd ever
done at high speed, and I feel lucky to not have crashed.

I was on a bike I've ridden for over 30 years. I modulated the
cantilever brakes perfectly. But I think if I had new discs with low
hand effort, I'd almost certainly have locked them up and gone down hard.

Granted, such an experience is extremely rare for me. But I'd still like
all my bikes to require roughly the same amount of brake lever force.



You’d think it would be so, but really quite differing brakes don’t seem to
cause confusion. I will admit that first time I use the MTB with is 180mm
etc disks they are so instant, but actually you don’t lock, it’s a very
easy system to use to it’s full, ie tyres at the point of locking but not
quite etc.

Roger Merriman

If you're applying the disk brakes and hit a bump it is WAY too easy to lock the brakes up.

wrote:
On Tuesday, January 29, 2019 at 6:07:16 AM UTC-8, Roger Merriman wrote:
Frank Krygowski wrote:
On 1/27/2019 8:21 PM, Roger Merriman wrote:
wrote:
On Sunday, January 27, 2019 at 3:43:22 AM UTC-8, Roger Merriman wrote:
Tom Evans wrote:
On 25/01/2019 00:19, Mark J. wrote:

I've been tempted to buy a cheap fat bike for the novelty; I expect it
would handle like a tank.


I got a cheap adventure (like a cross) bike, 40mm tyre, as a stopgap
when my normal road bike was out of action for a few weeks.

The results were very surprising. The geometries were the same, the tyre
rolling resistance didn't appear to be much different and the extra 4kg
didn't appear to make much difference to my speed.

On the plus size it was a more comfortable to ride, it felt slightly
more solid on the road.

I now ride it all the time in preference to my road bike.




Few years back I bought a cheap but relaxed CX bike pre adventure bikes
etc, it had its issues mainly it’s brakes which where canti and couldn’t
cope with being used like a MTB lite, it’s weight I generally didn’t
notice, I even took it up Mt Teide

I replaced it last year with a adventure bike, which main advantages are
better brakes cable disk vs canti and 2/9 vs 3/7 gearing.

It is my road bike, I do tend to run CX sized tyres as generally is more
choice and to give mud clearance. But I do notice how it rides bumps and
frankly is much more grip, some will be the type of tyres, some the size.

I don’t appear to be any slower, checking my times. Any differences are
marginal.

Roger Merriman

I had exactly the same problem with my Ridley XBow. Then I bought a set
of TRP 9.0 V-brakes and all of the stopping problems disappeared.

On my Redline Conquest I fitted Avid hydraulic disks and the braking was
WAY too strong. So strong that it is difficult to modulate it. I would
suspect that if I were doing it again I would use those tiny diameter road bike disks.


I assume they where mini Vs? Either way in the end though I used posh pads
to improve the brakes, I was unconvinced that there would be much
improvement for my use, ie MTB lite in many cases.

I’ve never yet had a Hydro system that was too powerful, don’t get me wrong
the play MTB has far more powerful brakes than the old Commute beast, so I
if I forget it’s a bit of surprise how much bite, how quickly but you adapt
quickly.

My worry about touchy brakes is about reflex action in a true emergency
situation. I've written about the time I was on a 30mph downhill and a
couple deer walked out of the woods. It was the hardest braking I'd ever
done at high speed, and I feel lucky to not have crashed.

I was on a bike I've ridden for over 30 years. I modulated the
cantilever brakes perfectly. But I think if I had new discs with low
hand effort, I'd almost certainly have locked them up and gone down hard.

Granted, such an experience is extremely rare for me. But I'd still like
all my bikes to require roughly the same amount of brake lever force.



You’d think it would be so, but really quite differing brakes don’t seem to
cause confusion. I will admit that first time I use the MTB with is 180mm
etc disks they are so instant, but actually you don’t lock, it’s a very
easy system to use to it’s full, ie tyres at the point of locking but not
quite etc.

Roger Merriman

If you're applying the disk brakes and hit a bump it is WAY too easy to lock the brakes up.


I’ve not noticed that, with my bikes. The only bike I do lock occasionally
is the gravel bike which has weaker brakes as its cable and much more
forward position so braking for folks in single track lanes the rear has
momentary locked, braking over bumps though no.

Roger Meriman

On 30/1/19 6:13 am, wrote:
On Tuesday, January 29, 2019 at 6:07:16 AM UTC-8, Roger Merriman wrote:


You’d think it would be so, but really quite differing brakes don’t seem to
cause confusion. I will admit that first time I use the MTB with is 180mm
etc disks they are so instant, but actually you don’t lock, it’s a very
easy system to use to it’s full, ie tyres at the point of locking but not
quite etc.


If you're applying the disk brakes and hit a bump it is WAY too easy to lock the brakes up.


Disk brakes are normally associated with better brake modulation than
rim brakes. That means with disk brakes you can achieve more brake
effort without locking a wheel. You seem to be contradicting that.

--
JS

On Tuesday, January 29, 2019 at 2:59:39 PM UTC-8, James wrote:
On 30/1/19 6:13 am, wrote:
On Tuesday, January 29, 2019 at 6:07:16 AM UTC-8, Roger Merriman wrote:


You’d think it would be so, but really quite differing brakes don’t seem to
cause confusion. I will admit that first time I use the MTB with is 180mm
etc disks they are so instant, but actually you don’t lock, it’s a very
easy system to use to it’s full, ie tyres at the point of locking but not
quite etc.


If you're applying the disk brakes and hit a bump it is WAY too easy to lock the brakes up.


Disk brakes are normally associated with better brake modulation than
rim brakes. That means with disk brakes you can achieve more brake
effort without locking a wheel. You seem to be contradicting that.

My front hydraulic disc modulates a lot like a good dual pivot. The rear takes less lever force than a rear dual pivot to generate the same stopping power. I had to recalibrate my right hand. Locking a rear brake is usually low consequence.

-- Jay Beattie.

On 1/29/2019 9:14 PM, jbeattie wrote:
On Tuesday, January 29, 2019 at 2:59:39 PM UTC-8, James wrote:

Disk brakes are normally associated with better brake modulation than
rim brakes. That means with disk brakes you can achieve more brake
effort without locking a wheel. You seem to be contradicting that.

My front hydraulic disc modulates a lot like a good dual pivot. The rear takes less lever force than a rear dual pivot to generate the same stopping power. I had to recalibrate my right hand. Locking a rear brake is usually low consequence.

Trying for some actual technical discussion here. (Weird, I know.)

As I understand it, good brake modulation would mean the retarding force
on the wheel would be strictly proportional to hand force on the lever.
There would be no situation where a slight increase in lever force
caused a sharp increase in brake force. There would be no situation
where slightly decreasing hand force did not reduce brake force
proportionally.

So what makes a brake have bad modulation?

Friction in mechanical bits, I'm sure. That would include brake inner
wires in their housing or leaving their housing. (Sometimes things are
crooked at the exit.) Also any friction at pivots or bearing surface,
any sliding contact like where return springs contact the brake arms on
certain models of caliper brakes.

Any non-linear linkage systems, at least once friction material contacts
the rim, disc or whatever. Like the infamous Campy Delta brakes, whose
mechanical advantage changed radically as pads wore. (I suppose you
could have non-linear linkages in the levers as well as in the brakes
themselves.)

Moisture on brake pads that must be wiped away before the friction
coefficient can rise.

Any "self actuation" mechanism, like what's designed into almost every
drum brake.

Is there anything I'm missing?

And is there a chance "good modulation" would use something other than a
direct proportion between hand force and brake retarding force? For
example, might we want the slope of the brake force vs. hand force curve
to decrease for large hand forces, to lessen the chance of an
over-the-bars event? ISTM Shimano did something like this by putting a
spring in series with the front brake cable on some "comfort bikes."

Thoughts? (Or should we just go back to arguing about bombing Viet Nam?)

--
- Frank Krygowski

On Tuesday, January 29, 2019 at 2:59:39 PM UTC-8, James wrote:
On 30/1/19 6:13 am, wrote:
On Tuesday, January 29, 2019 at 6:07:16 AM UTC-8, Roger Merriman wrote:


You’d think it would be so, but really quite differing brakes don’t seem to
cause confusion. I will admit that first time I use the MTB with is 180mm
etc disks they are so instant, but actually you don’t lock, it’s a very
easy system to use to it’s full, ie tyres at the point of locking but not
quite etc.


If you're applying the disk brakes and hit a bump it is WAY too easy to lock the brakes up.


Disk brakes are normally associated with better brake modulation than
rim brakes. That means with disk brakes you can achieve more brake
effort without locking a wheel. You seem to be contradicting that.

--
JS

Not really. A full suspension MTB has a different center of gravity and weighs twice what a road or cross bike does. When you have 2" wide tires and a great deal of weight disks do modulate much better because you can retain traction most of the time.

There are two problems with a xcross bike - it weighs very little - a 32 mm cross knobbie can easily have so much traction that the bike can rotate around it's much high center of gravity. And on hard surfaces you can lock the brakes very easily since there is less traction.

With road bikes they reduced the size of the disks dramatically. The reason that they even went to disks was to not wear out expensive carbon rims. So instead they wear out easily and cheaply replaceable metal disks. Using Campy skeleton brakes I can easily lock the brakes if I wish to. So what would I gain using disks other than cheaper replacement costs?

I am not anti-disk brakes but there are horses for courses. If you are building a superlight bike with superlight components why would you put an very un-aerodynamic and heavy disk brake systems on it?

3 months of riding my Colnago with carbon wheels show less wear that a single month on aluminum wheels. Though I have to replace the basalt brake pads all the time.

Frank Krygowski wrote:

:As I understand it, good brake modulation would mean the retarding force
n the wheel would be strictly proportional to hand force on the lever.
:There would be no situation where a slight increase in lever force
:caused a sharp increase in brake force. There would be no situation
:where slightly decreasing hand force did not reduce brake force
roportionally.

:So what makes a brake have bad modulation?

A large part of it is the friction materials. brake pad linings as
used on rim brakes are grabby and don't slide well. the retarding
force they generate isn't linear with the force pushing them into the
surface, espcially at low pressure. the harder material used for most
disk brake pads slides better, and have more linear behavior.


--
sig 65

On Wednesday, January 30, 2019 at 11:58:45 AM UTC-8, David Scheidt wrote:
Frank Krygowski wrote:

:As I understand it, good brake modulation would mean the retarding force
n the wheel would be strictly proportional to hand force on the lever.
:There would be no situation where a slight increase in lever force
:caused a sharp increase in brake force. There would be no situation
:where slightly decreasing hand force did not reduce brake force
roportionally.

:So what makes a brake have bad modulation?

A large part of it is the friction materials. brake pad linings as
used on rim brakes are grabby and don't slide well. the retarding
force they generate isn't linear with the force pushing them into the
surface, espcially at low pressure. the harder material used for most
disk brake pads slides better, and have more linear behavior.

I'm not an engineer, but it seems to me that rear rim brakes have lots of losses from cable housing compression and a long cable runs. A rear hydraulic disc feels like a really good front dual pivot -- except on the rear. Most people are not used to getting that kind of stopping power from a fairly light pull on the lever.

-- Jay Beattie.

Frank Krygowski wrote:
On 1/29/2019 9:14 PM, jbeattie wrote:
On Tuesday, January 29, 2019 at 2:59:39 PM UTC-8, James wrote:

Disk brakes are normally associated with better brake modulation than
rim brakes. That means with disk brakes you can achieve more brake
effort without locking a wheel. You seem to be contradicting that.

My front hydraulic disc modulates a lot like a good dual pivot. The
rear takes less lever force than a rear dual pivot to generate the same
stopping power. I had to recalibrate my right hand. Locking a rear
brake is usually low consequence.

Trying for some actual technical discussion here. (Weird, I know.)

As I understand it, good brake modulation would mean the retarding force
on the wheel would be strictly proportional to hand force on the lever.
There would be no situation where a slight increase in lever force
caused a sharp increase in brake force. There would be no situation
where slightly decreasing hand force did not reduce brake force
proportionally.

So what makes a brake have bad modulation?

Friction in mechanical bits, I'm sure. That would include brake inner
wires in their housing or leaving their housing. (Sometimes things are
crooked at the exit.) Also any friction at pivots or bearing surface,
any sliding contact like where return springs contact the brake arms on
certain models of caliper brakes.

Any non-linear linkage systems, at least once friction material contacts
the rim, disc or whatever. Like the infamous Campy Delta brakes, whose
mechanical advantage changed radically as pads wore. (I suppose you
could have non-linear linkages in the levers as well as in the brakes
themselves.)

Moisture on brake pads that must be wiped away before the friction
coefficient can rise.

Any "self actuation" mechanism, like what's designed into almost every
drum brake.

Is there anything I'm missing?

And is there a chance "good modulation" would use something other than a
direct proportion between hand force and brake retarding force? For
example, might we want the slope of the brake force vs. hand force curve
to decrease for large hand forces, to lessen the chance of an
over-the-bars event? ISTM Shimano did something like this by putting a
spring in series with the front brake cable on some "comfort bikes."

Thoughts? (Or should we just go back to arguing about bombing Viet Nam?)


About the only thing I would add is that there may be hysteresis in the
mechanism, so a single force vs hand force curve may not show everything,
and you may have to plot it going up and coming back down.