Olmo

On Friday, July 14, 2017 at 5:35:15 PM UTC-7, John B. wrote:
On Fri, 14 Jul 2017 06:48:40 -0700 (PDT), wrote:

On Thursday, July 13, 2017 at 5:49:05 PM UTC-7, John B. wrote:
On Thu, 13 Jul 2017 07:39:08 -0700 (PDT), wrote:

On Wednesday, July 12, 2017 at 5:07:09 PM UTC-7, John B. wrote:
On Wed, 12 Jul 2017 07:45:10 -0700 (PDT), wrote:

On Tuesday, July 11, 2017 at 5:26:59 PM UTC-7, John B. wrote:
On Tue, 11 Jul 2017 07:29:14 -0700 (PDT), wrote:

On Monday, July 10, 2017 at 5:53:39 PM UTC-7, John B. wrote:
On Mon, 10 Jul 2017 07:17:51 -0700 (PDT), wrote:

On Friday, July 7, 2017 at 1:09:09 PM UTC-7, Joerg wrote:
On 2017-07-07 09:24, wrote:
On Friday, July 7, 2017 at 9:10:54 AM UTC-7, Frank Krygowski wrote:
On 7/7/2017 4:25 AM, John B. wrote:

I read an article about different handling between different
bikes. The author and his buddy, a frame maker, even cobbled up a
fork with adjustable trail.

Anyway, they found that the Italian frames tended toward lower
bottom bracket heights, in other words lower C/G, which they
attributed to a more stable feeling bike.

As I've said many times, I'm far from being a connoisseur of bike
handling. But it doesn't make sense to me that a lower center of
gravity would make a bike feel more stable.

First, the effect would seem to be minuscule if it existed. The
center of mass of a bike+rider is generally somewhere around the
saddle, i.e. maybe 40" high. I'd think lowering the center of mass
by half an inch would make a tiny difference compared to other
changes.

But more important: To me, stability in a bike means it requires
less frequent and energetic steering corrections to maintain
balance. And in that respect, an "ordinary" or "high wheeler" is
far, far more stable than a normal bike. Likewise, a recumbent is
far less stable. The first time I road an ordinary, I was able to
easily balance at 2 mph. The first time I rode a recumbent, I
couldn't even balance. Someone had to run alongside and hold me up
as I flopped left and right, until I could relax and let the bike
work properly.

The difference is polar moment of inertia about the axis along the
ground between the two tire contact patches. With the
"ordinary's" rider mass at about five feet or more, the sideways
rotation needed for a fall begins much more slowly. There's plenty
of time to correct even the tiniest deviation from vertical. By
contrast, with a recumbent's center of mass at maybe 18", the
sideways rotation initiates quickly.

The same effect can be observed by trying to balance a yardstick
(or meter stick) on its edge, vs. trying to balance a 6" (or 15 cm)
ruler. Or trying to vertically balance a shovel or hammer with
heavy side up vs. down.

So if a higher center of mass is more stable for ordinaries,
yardsticks and other objects, I don't see why it would be opposite
for bikes.

Well you're wrong. Firstly the saddle is also lower since the saddle
height is measured from the pedal center. And in many high speed
corners you put your weight on the outside pedal which is lower. Also
the arc through which it passes is lower. There is about an inch
difference in height and it is very noticeable believe me.


I'll second that. My MTB doesn't corner nearly as well as my much lower
CG road bike and the difference is not in the tires. I've tried with
another MTB that the owner had equipped with slick road tires (he
doesn't own a road bike), same thing.

With MTB cornering often happens in a very different way, keeping the
bike more straight up but leaning out and putting a leg out for
skidding. Like dirt bikers sometimes do.

While watching the Tour yesterday, one of the announcers was saying that one of the competitors had raced mountain bikes so that gave him an advantage in cornering road bikes. I told my wife that was a bunch of BS because cornering an MTB is totally different from cornering a road bike and sticking a knee out on a fast corner is more likely to get you in trouble than help. Most of the time the only way you can corner an MTB hard is by having a berm

Why is that? The larger tires or the suspension? Or the coarse tread
on the tires?

Apparently it gave him better knowledge of how to corner on hard surfaces. I just assigned it to the trash heap of things that announcers say to fill the silence.

I meant your comment that "Most of the time the only way you can
corner an MTB hard is by having a berm" and I wondered why.

I've ridden MTB's since the days of the fat tire bikes in Marin. I KNOW that you can't corner on most trails because they have loose surfaces.. Even hard surfaces are generally uneven.

So if you corner hard it's almost always against a berm. We did this in off-road motorcycles as well.

Ah, so it is the terrain not the actual bicycle that you were
referring to. I had thought that you meant a difference in cornering
ability of the bicycle itself.

MTB's do not corner. Despite the fat tires if you have any speed you have to corner either on hard rock with virtually no traction or loose dust with same.

When they show these marvelous scenes of hard cornering on off-road they are on berms.

Now with a full suspension you CAN do amazing drops over terrain you'd swear would throw you off-line and crash you. And you accelerate almost at the speed of gravity. But cornering is something else.

I asked as I've got a MTB frame that I use. I replaced the telescoping
forks with sold and use it as a "utility bike". With 1-1/2 inch tires
it seems to corner just fine on paved and unpaved roads.

John, I would have thought it to be self evident that I was speaking of the terrain and not the geometry.

Perhaps so, I suppose I read MTB+cornering and just assumed that it
meant cornering and not cornering on loose soil. I stand corrected.

It is still true on pavement because you are riding knobbies

On 7/14/2017 5:44 PM, AMuzi wrote:
On 7/14/2017 4:32 PM, Doug Landau wrote:
On Friday, July 14, 2017 at 12:43:51 PM UTC-7, wrote:
On Friday, July 14, 2017 at 9:21:19 AM UTC-7, Doug Landau wrote:

sports bikes?

What sort of bikes do you have Doug? And then which one's do you ride?

It doesn't matter thats my point
The group is no more for competitive riders than it is for commuters


Hence Sports, the perfect bicycle:
http://www.yellowjersey.org/53sports.jpg

Cool! He and I have the same front hub! (Except mine is two years newer.)


--
- Frank Krygowski

On Friday, July 14, 2017 at 2:32:45 PM UTC-7, Doug Landau wrote:
On Friday, July 14, 2017 at 12:43:51 PM UTC-7, wrote:
On Friday, July 14, 2017 at 9:21:19 AM UTC-7, Doug Landau wrote:

sports bikes?

What sort of bikes do you have Doug? And then which one's do you ride?

It doesn't matter thats my point
The group is no more for competitive riders than it is for commuters

BS - while I have no problem with whatever you ride and however your ride, your opinion on fast race bikes isn't pertinent unless you ride fast race bikes fast.

On Friday, July 14, 2017 at 7:49:04 PM UTC-7, Frank Krygowski wrote:
On 7/14/2017 5:44 PM, AMuzi wrote:
On 7/14/2017 4:32 PM, Doug Landau wrote:
On Friday, July 14, 2017 at 12:43:51 PM UTC-7, wrote:
On Friday, July 14, 2017 at 9:21:19 AM UTC-7, Doug Landau wrote:

sports bikes?

What sort of bikes do you have Doug? And then which one's do you ride?

It doesn't matter thats my point
The group is no more for competitive riders than it is for commuters


Hence Sports, the perfect bicycle:
http://www.yellowjersey.org/53sports.jpg

Cool! He and I have the same front hub! (Except mine is two years newer..)

Frank, to remind you of our argument: I said that a lower CG allowed riders to corner faster and you came up with the cyclist diagram that you didn't appear to understand. (If you shorten leg B-C you shorten the hypotenuse and reduce corning forces. Granted, this isn't much but it is descernable.)

Here is an article from Bicycling: (Cervelo R5)

"Engineers also tweaked handling -- increasing BB drop by 4 mm...to improve the bike's stability".

So this isn't just me pulling something off of the top of my head.

On 7/15/2017 3:43 PM, wrote:

Frank, to remind you of our argument...

Don't "remind me of the argument." Quote me, using the
ultra-sophisticated "highlight, copy, paste" technique. If you can't
show I'm wrong by that method, just drop it.

--
- Frank Krygowski

On Saturday, July 15, 2017 at 8:21:36 PM UTC-7, Frank Krygowski wrote:
On 7/15/2017 3:43 PM, wrote:

Frank, to remind you of our argument...

Don't "remind me of the argument." Quote me, using the
ultra-sophisticated "highlight, copy, paste" technique. If you can't
show I'm wrong by that method, just drop it.

--
- Frank Krygowski

If you can't remember your center of mass vs, force illustration then perhaps this is too complicated for you. Quote indeed!

On Saturday, July 15, 2017 at 12:44:02 PM UTC-7, wrote:
On Friday, July 14, 2017 at 7:49:04 PM UTC-7, Frank Krygowski wrote:
On 7/14/2017 5:44 PM, AMuzi wrote:
On 7/14/2017 4:32 PM, Doug Landau wrote:
On Friday, July 14, 2017 at 12:43:51 PM UTC-7, wrote:
On Friday, July 14, 2017 at 9:21:19 AM UTC-7, Doug Landau wrote:

sports bikes?

What sort of bikes do you have Doug? And then which one's do you ride?

It doesn't matter thats my point
The group is no more for competitive riders than it is for commuters


Hence Sports, the perfect bicycle:
http://www.yellowjersey.org/53sports.jpg

Cool! He and I have the same front hub! (Except mine is two years newer.)

Frank, to remind you of our argument: I said that a lower CG allowed riders to corner faster and you came up with the cyclist diagram that you didn't appear to understand. (If you shorten leg B-C you shorten the hypotenuse and reduce corning forces. Granted, this isn't much but it is descernable.)

Here is an article from Bicycling: (Cervelo R5)

"Engineers also tweaked handling -- increasing BB drop by 4 mm...to improve the bike's stability".

So this isn't just me pulling something off of the top of my head.

What does Jan Heine say?

On 2017-07-13 07:39, wrote:
On Wednesday, July 12, 2017 at 5:07:09 PM UTC-7, John B. wrote:
On Wed, 12 Jul 2017 07:45:10 -0700 (PDT),
wrote:

On Tuesday, July 11, 2017 at 5:26:59 PM UTC-7, John B. wrote:
On Tue, 11 Jul 2017 07:29:14 -0700 (PDT),
wrote:

On Monday, July 10, 2017 at 5:53:39 PM UTC-7, John B. wrote:
On Mon, 10 Jul 2017 07:17:51 -0700 (PDT),
wrote:

On Friday, July 7, 2017 at 1:09:09 PM UTC-7, Joerg
wrote:
On 2017-07-07 09:24, wrote:
On Friday, July 7, 2017 at 9:10:54 AM UTC-7, Frank
Krygowski wrote:
On 7/7/2017 4:25 AM, John B. wrote:

I read an article about different handling
between different bikes. The author and his
buddy, a frame maker, even cobbled up a fork with
adjustable trail.

Anyway, they found that the Italian frames tended
toward lower bottom bracket heights, in other
words lower C/G, which they attributed to a more
stable feeling bike.

As I've said many times, I'm far from being a
connoisseur of bike handling. But it doesn't make
sense to me that a lower center of gravity would
make a bike feel more stable.

First, the effect would seem to be minuscule if it
existed. The center of mass of a bike+rider is
generally somewhere around the saddle, i.e. maybe
40" high. I'd think lowering the center of mass by
half an inch would make a tiny difference compared
to other changes.

But more important: To me, stability in a bike
means it requires less frequent and energetic
steering corrections to maintain balance. And in
that respect, an "ordinary" or "high wheeler" is
far, far more stable than a normal bike. Likewise,
a recumbent is far less stable. The first time I
road an ordinary, I was able to easily balance at 2
mph. The first time I rode a recumbent, I couldn't
even balance. Someone had to run alongside and
hold me up as I flopped left and right, until I
could relax and let the bike work properly.

The difference is polar moment of inertia about the
axis along the ground between the two tire contact
patches. With the "ordinary's" rider mass at about
five feet or more, the sideways rotation needed for
a fall begins much more slowly. There's plenty of
time to correct even the tiniest deviation from
vertical. By contrast, with a recumbent's center
of mass at maybe 18", the sideways rotation
initiates quickly.

The same effect can be observed by trying to
balance a yardstick (or meter stick) on its edge,
vs. trying to balance a 6" (or 15 cm) ruler. Or
trying to vertically balance a shovel or hammer
with heavy side up vs. down.

So if a higher center of mass is more stable for
ordinaries, yardsticks and other objects, I don't
see why it would be opposite for bikes.

Well you're wrong. Firstly the saddle is also lower
since the saddle height is measured from the pedal
center. And in many high speed corners you put your
weight on the outside pedal which is lower. Also the
arc through which it passes is lower. There is about
an inch difference in height and it is very
noticeable believe me.


I'll second that. My MTB doesn't corner nearly as well
as my much lower CG road bike and the difference is not
in the tires. I've tried with another MTB that the
owner had equipped with slick road tires (he doesn't
own a road bike), same thing.

With MTB cornering often happens in a very different
way, keeping the bike more straight up but leaning out
and putting a leg out for skidding. Like dirt bikers
sometimes do.

While watching the Tour yesterday, one of the announcers
was saying that one of the competitors had raced mountain
bikes so that gave him an advantage in cornering road
bikes. I told my wife that was a bunch of BS because
cornering an MTB is totally different from cornering a
road bike and sticking a knee out on a fast corner is
more likely to get you in trouble than help. Most of the
time the only way you can corner an MTB hard is by having
a berm

Why is that? The larger tires or the suspension? Or the
coarse tread on the tires?

Apparently it gave him better knowledge of how to corner on
hard surfaces. I just assigned it to the trash heap of things
that announcers say to fill the silence.

I meant your comment that "Most of the time the only way you
can corner an MTB hard is by having a berm" and I wondered
why.

I've ridden MTB's since the days of the fat tire bikes in Marin.
I KNOW that you can't corner on most trails because they have
loose surfaces. Even hard surfaces are generally uneven.

So if you corner hard it's almost always against a berm. We did
this in off-road motorcycles as well.

Ah, so it is the terrain not the actual bicycle that you were
referring to. I had thought that you meant a difference in
cornering ability of the bicycle itself.

MTB's do not corner. Despite the fat tires if you have any speed you
have to corner either on hard rock with virtually no traction or
loose dust with same.

When they show these marvelous scenes of hard cornering on off-road
they are on berms.


Can be done sans berms but a lot of stuff goes flying and it causes
serious trail erosion. Which is why I usually don't do it (and because I
often don't wear suitable shoes):

https://www.youtube.com/watch?v=jA0vy9sbiNw


Now with a full suspension you CAN do amazing drops over terrain
you'd swear would throw you off-line and crash you. And you
accelerate almost at the speed of gravity. But cornering is something
else.


Until the rear bottoms out. That is a horrid sound. Happend twice to me
and I don't want to experience that again.

--
Regards, Joerg

http://www.analogconsultants.com/