What makes bikes handle differently? Can a bike be too light?

[Peter Cole]

"Tim McNamara" <[email protected]> wrote in message
news:[email protected]...
> In article <DqYna.515526$F1.72830@sccrnsc04>, "Peter Cole" <[email protected]> wrote:
>
> > You can toss the bike violently from side-to-side, or not at all.
Obviously
> > the side-to-side thrashing is harder on the bike
>
> In what way?

It can put big (relative to normal riding) side loads on the wheels. Also, from the recent frame
failure discussion, the consensus seemed to be that high intermittent peak loads can significantly
accelerate fatigue in frames and components. I had a lugged steel frame in a fixed gear
configuration, which I rode a good deal standing, it failed at the lower head tube (cracked), right
at the lug boundary, a typical failure mode for these frames. I think "frame tossing" puts more
out-of-plane, torsion (twisting) stresses on a frame.

 

[Peter Cole]

> > It is especially not common on hills, steep or otherwise. The type of
pedaling
> > you describe isn't sustainable for any duration. Unless it's a finish line sprint, it's posing
> > -- inefficient, dangerous, and hard on the bike.
> >
> > http://www.sheldonbrown.com/standing.html
>
> Disagree. Standing is just a different style, that's all. I'm not going to say it's more efficient
> or faster, but it's a valid technique and appropriate at times.

I was referring to the practice of swinging the bike when out of the saddle, not riding out of the
saddle in general.

 

[Peter Cole]

"Tom Sherman" <[email protected]> wrote in message news:[email protected]...
>
> eric bazan wrote:
> > ... Standing while going up hills makes it possible to push a bigger gear and use a lower
> > cadence....
>
> Is there any advantage to doing this, unless one is already using the lowest gear on the bicycle?

I think that a lot of the out of the saddle hill climbing you see is from people refusing (for ego
reasons) to buy lower gearing, forcing them to climb in a too tall gear.

 

[Mike S.]

"Captain Dondo" <[email protected]> wrote in message
news[email protected]...
> On Fri, 18 Apr 2003 15:36:47 +0000, Stephen Harding wrote:
>
> >
> > Neither do I see why banking the bike back and forth while standup
pedaling
> > would be especially bad for the bike. Perhaps putting more lateral
forces on
> > frame (frame weakest in lateral stiffness), but a quality bike frame
shouldn't
> > be too upset with such forces.
> >
>
> I ride with an ex-linebacker. This guy tips the scales at 260# + with power to match. If you're
> drafting him and he gets up to sprint, you can see the frame and the rear wheel flex. I mean the
> rear wheel gets out of line by about 3 inches with the front, due to frame flex.
>
That's not Skip Foley is it? I was watching Skip race the Manassas, VA crit one year and
noticed that his bike was just flexing all over the place under him! Certainly wouldn't want to
be THAT bike!

Most of us aren't blessed (cursed?) with being that large and strong.

> He completely trashed several Trek frames, due to excessive flex. Trek simply doesn't make frames
> strong enough for a rider like that. No frame failure, but simply a substantial loss of rigidity
> in the frame.
>
> So yes, a big powerful rider can overpower a bike or frame, and excessive flex can be hard on a
> quality frame.
>
> -Dondo

 

[Mike S.]

"Peter Cole" <[email protected]> wrote in message
news:x4goa.530944$F1.75049@sccrnsc04...
> "Mike S." <mikeshaw2@coxDOTnet> wrote in message news:Gb3oa.1592$366.810@fed1read06...
> >
> > Sprinting is one of the things I love about cycling. The speed, the
power,
> > the rush, the sense of accomplishment when you're done. Just riding
along
> > (JRA) doesn't have nearly the same effect. I understand that not
everyone
> > is like me, so YMMV when it comes to enjoying sprinting. But just like green eggs and ham, try
> > it, you may like it!
>
> Believe it or not, I have done the occasional sprint, but thanks for the condescension anyway. My
> comments weren't about sprinting, but thrashing
the
> bike from side-to-side.
>
>
> > Hmmm, the SDBC ride here in San Diego does about the same thing, but is always won by a guy
> > standing up sprinting for the last 50-100m. Towards
the
> > late spring/summer, I'm actually one of the ones up there sprinting "for
the
> > win." You ever see Cipollini take an all out sprint seated? He gets
the
> > big tow to the line seated, but for that last explosive burst to the
line,
> > nothing beats the standing sprint.
>
> I'm sure you and Cipollini are both impressive sights. Our finish sprints
tend
> to be much longer, and usually seated.
>
Acutally, I'm not as impressive as Cipo, nor do I look as good (on or off the bike), but I
do have fun.

The finishing stretch on the SDBC ride is several miles long. The leadout starts in Leucadia, the
sprint actually happens at the Solana Beach sign. I watched from about 15th today as the leadout for
the sprint began in earnest at about 1/2mi to go, with the sprint happening in the last 50-100m.
When the two guys that I had marked jumped, I hesitated, and all was lost...

Not bad for someone with heavy legs today.

> > ...and when was the last time that happened to you? A chain skipping
isn't
> > going to cause a crash unless you're completely "equilibriumly
challenged."
> > Basic maintenence takes care of the rest...
>
> Last time for me was several years ago, new chain, worn sprocket, MTB with very low bars...
>
> I've seen quite a few of these though over the years, mostly pedal pull
outs,
> but even when riders haven't gone down from a chain skip, if they're
standing,
> they often wobble violently. I've seen a few pack crashes caused that way.
>

> > Hell, you might as well worry about some idiot in a car hitting you if you're worried about a
> > chain skipping or a pedal falling out. In the likelihood category, both occurences are very rare
> > for a decently
maintained
> > bike.
>
> Chain skips and pedal *pull outs* aren't all that rare in my neck of the woods.

 

[Andrew Bradley]

Tim McNamara :

> People stand to sprint in order to use their weight on the pedals, not because there's
> "significant extra power" available from the upper body.

Standing does of course make more weight available to push against and the arms provide extra
reaction force too. But it is still strange that riders will sprint out of the saddle on big gears
rather than sit and spin at the sort of revs that give max power on an ergometer (which I believe
isn't limited by reaction force).

The arm-work is not negligible and the legs work in a different way to when you are seated which
could also affect max power.

Do you think out-of-saddle riding is no more powerful than seated riding?

> Watch the pros race. Many of the top sprinters do most of their sprint sitting down; this is even
> more apparent in track sprinters. Standing for 200-300 meters of all-out sprinting is not
> effective for most riders (Abdujaparov being a notable exception). Amateurs tend to be more likely
> to sprint standing, but the sprints tend to only be 50-100 meters long.

Don't know which pros you're watching and your amateurs must be schoolboys. I'm only talking about
the maximal effort part not the wind up.

Trackies don't count since they don't have gears. You have to sit at those RPM. And when they ride
the road, they do like everybody else.

Andrew Bradley

 

[John Forrest To]

"Captain Dondo" <[email protected]> wrote in message

> Aluminum makes a lousy spring. You bend it enough times, it loses its strength. No single point
> failure, just goes soft as a noodle.

Losing strength and going soft are not at all the same thing. Bend some aluminum back and forth a
bit and see what happens. It may get weaker yes, but not softer.

JT

--
*******************************************
NB: reply-to address is munged

Visit http://www.jt10000.com
*******************************************

 

[Mark Hickey]

"Captain Dondo" <[email protected]> wrote:

>On Sat, 19 Apr 2003 16:28:50 +0000, Mark Hickey wrote:
>
>> You need to do an experiment. Sneak over to the linebacker's house, and get his bike. Now
>> wedge it between a couple solid objects and pull on the back end until it moves three inches
>> "out of line".
>
>I'm talking lateral flex. The front wheel tracks true; the rear wheel tracks in an S curve... Some
>of it may be line of sight stuff, but any frame will flex under enough power. His far more than
>most. Trek frames aren't built for that kind of weight...

I figured it was lateral flex. My point was that if you DID manage to actually flex a frame 3"
off-center, it was going to be permanently damaged.

>> 'Splain me, Lucy. How does the structure of the metal change without failing?
>
>Aluminum makes a lousy spring. You bend it enough times, it loses its strength. No single point
>failure, just goes soft as a noodle. That's why springs are steel. I've had one alum. frame end up
>that way after about 5 hard seasons. The frame just loses its liveliness.

Heh. That is entirely, totally, and unreservedly false, but common mythology in many bike shops
among the "experts".

Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame

 

[Fabrizio Mazzol]

"Captain Dondo" <[email protected]> wrote in message >
> I ride with an ex-linebacker. This guy tips the scales at 260# + with power to match. If you're
> drafting him and he gets up to sprint, you can see the frame and the rear wheel flex. I mean the
> rear wheel gets out of line by about 3 inches with the front, due to frame flex.
>
Well for one thing that guy is 105 lbs too heavy to be a cyclist.

You can't go from being a linebacker to cyclist, it's just not done.

 

[Tom Keats]

In article <[email protected]>, [email protected] (John Forrest
Tomlinson) writes:

> Losing strength and going soft are not at all the same thing. Bend some aluminum back and forth a
> bit and see what happens. It may get weaker yes, but not softer.

Maybe it becomes work-hardened (and more brittle)?

I truly don't know. I'm asking out of curiosity. Can aluminum be work-hardened, and does the process
make it more brittle?

cheers, Tom

--
-- Powered by FreeBSD Above address is just a spam midden. I'm really at: tkeats [curlicue] vcn
[point] bc [point] ca

 

[Mike S.]

"Andrew Bradley" <[email protected]> wrote in message
news:[email protected]...
>
> Tim McNamara :
>
> > People stand to sprint in order to use their weight on the pedals, not because there's
> > "significant extra power" available from the upper body.
>
> Standing does of course make more weight available to push against and the arms provide extra
> reaction force too. But it is still strange that
riders
> will sprint out of the saddle on big gears rather than sit and spin at
the
> sort of revs that give max power on an ergometer (which I believe isn't limited by
> reaction force).
>
> The arm-work is not negligible and the legs work in a different way to
when
> you are seated which could also affect max power.
>
> Do you think out-of-saddle riding is no more powerful than seated riding?
>
> > Watch the pros race. Many of the top sprinters do most of their sprint sitting down; this is
> > even more apparent in track sprinters. Standing for 200-300 meters of all-out sprinting is not
> > effective for most riders (Abdujaparov being a notable exception). Amateurs tend to be more
> > likely to sprint standing, but the sprints tend to only be 50-100 meters long.
>
> Don't know which pros you're watching and your amateurs must be
schoolboys.
> I'm only talking about the maximal effort part not the wind up.
>
> Trackies don't count since they don't have gears. You have to sit at those RPM. And when they ride
> the road, they do like everybody else.
>
At least THIS trackie does...

Mike

 

[Andy Dingley]

On Sat, 19 Apr 2003 16:28:50 GMT, Mark Hickey <[email protected]> wrote:

>A big powerful rider can experience excessive flex, and it's possible excessive flex can cause a
>failure in a frame eventually. Just don't get your knickers in a twist over your frame "going
>soft"... it simply doesn't happen.

Mine did. Remember those old (late '90s) GT LTS frames, with the four link rear suspension ? It
wasn't the frame tubes failing, but thunder-thighed mashers who stood up and pummeled those on a
climb could leave a trail of broken frame bearings behind them.

I got rid of mine - couldn't keep up with bearing maintenance on it.

 

[Andy Dingley]

On Sat, 19 Apr 2003 12:04:52 -0400, "Captain Dondo" <[email protected]> wrote:

>Aluminum makes a lousy spring. You bend it enough times, it loses its strength. No single point
>failure, just goes soft as a noodle.

"Strength" doesn't control "softness" against flex, that's stiffness.

Fatigued aluminium loses strength, but it gains stiffness (until it actually fails).

If your linebacker friend can actually feel the frame go soft, he should get off and walk - by that
point he's started to fracture it.

 

[B. Sanders]

"Robert Quindazzi" <[email protected]> wrote in message
news:<[email protected]>...
>
>
> While my experience is more limited than yours, I have riden/owned quite a few bikes

Then you have lived well, Bob. I hope you're still riding and enjoying bikes of all kinds.

> and while I agree they can all feel different, I have come to the conclusion that there is no
> practical effect.

They're all rideable, if that's what you mean.

> I don't think light weight, super rigidity, flexibility, different trail distances, shorter or
> longer seatstays, different materials etc... make any practical difference regardring the speed at
> which corners can be negotiated.

Hmm. Well, personally, I wasn't addressing cornering behavior in my posting; but now that you
mention it...

> While I doubt such a test has been done, it is my educated guess that bikes of widely varying
> designs, when shod with similar tires, would all corner at so similar a g level that any
> difference would be lost in the noise.

You could be right.

Changing tires changes handling. Changing tire size always changes handling noticeably (IME).

> I would also point out that corners taken at full g's are a rarity (at least when I ride), and
> that total time spent in all corners is so small when compared to total ride length, that even if
> there were a significant if cornering speed (say 2%), it would still be insignifcant in totality.

What I was saying is that during rapid acceleration, a light bike is going to be faster. This is
especially true for out-of-the saddle riding, particularly when climbing hills. I submit that while
the difference in the rider + bike system differs very little (between heavier and ligher bikes),
the effect of riding a light(er) bike up hills is an actual increase in climbing speed, due to the
ease of "tossing" the bike, and less energy lost in the riding technique due to the bike's inertia.
I call this property "flickability." There may be some additional benefit to having lighter wheels,
too; due to a reduced energy loss from fighting the rotational inertia of the wheels as their
attitude is changed constantly (while tossing the bike from side to side).

This also points to the likelihood that smaller wheels are ideal for fast bikes, since they are
lighter and thus have less rotational inertia than larger wheels. Alex Moulton believed this to be
true, as have many others.

I have not conducted a scientific test of my hypotheses. Yet.

> The above comments apply only to bikes used on pavement, as, obviously, mountain bikes are a
> different kettle of fish.

Mountain bikes are bikes, too. They benefit from superior engineering similarly to road bikes;
though their target handling characteristics are likely to be quite different.

Ride to ride,

-Barry

 

[B. Sanders]

"eric bazan" <[email protected]> wrote in message
news:[email protected]...
> "B. Sanders" <[email protected]> wrote in message
news:<wDAna.492580$F1.70476@sccrnsc04>...
> > Every spring, I re-learn the handling quirks of my various bikes. I'm somewhat fascinated with
> > bike handling, and I keep at least 8 bikes in
my
> > collection, usually more. I have owned 30+ bikes in the past 10 years, mainly for the purpose of
> > experiencing a wide array of basic designs,
frame
> > materials, wheel diameters and geometries. I've owned a huge range of bikes, from a sleek M5 low
> > racer recumbent (a wonderful beast) to a full-custom Merlin Ti hardtail, and quite a few
> > dumpster specials as
well.
> > They all have their own handling quirks, and all have contributed to my understanding of bike
> > handling factors.
> >
> (...)
>
> Nice post.

Thank you Eric.

> I too have owned many bikes, just not at the same time. ;-) Probably at least a dozen or so. This
> winter my last bike, which I'd owned for six years and put at least 50K miles on, got stolen (a
> giant iguana).

OMG! A giant iguana stole your bike!? Any leads? Did he shed his tail in the getaway?

> I've been out of the game for a while, so I was saddened when I finally got around to looking for
> another bike. Where have all the cheap steel bikes gone?

They're around.

> All the low to mid-range bikes now seem to made of aluminum. There's a very large bicycle dealer
> where I live (budget bicycle center, madison, wi). They have several shops in a small area,
> including a rather large warehouse full of used bikes. An overwhelming number of used bikes.

Have you been to Bicycle Exchange? I love that shop. Hope they're still around.

> They allow you to test ride a bike before you buy it, which is essential IMO.

Yes, it is essential. Walk away from any shop that won't let you test ride before you buy.

> It's amazing because you can look at a bike all day, but you've got to ride it to really know how
> it's going to handle and feel.

Some unscrupulous salespeople will try to deter you from assessing the bike's ride, and fill your
head with unsupportable claims and hyperbole. Add in a cup of pressure-sales tactics, and you have a
typical Saturday in a high-volume big-city bike shop.

> For this reason I'll never buy any bike unless I can ride it first. I probably tried about six
> bikes before I chose one, and test riding one after another really made the differences in
> handling obvious. Subtle, almost unnoticable variances in geometry really make a tremendous
> difference in how a bike handles.

Quite true! However, tire pressure is also a large contributor to handling characteristics. Other
important factors are handlebar width and height, saddle type and size, saddle fore/aft and tilt
adjustments, shifter adjustment, brake adjustment and stem length. All of these make a noticeable
difference.

> I don't claim to be able to quantify these things, but I know what I like.

And if you like what you bought, then you have done well.

> I agree that one can learn to accomodate any bike, and usually the one that feels best of the
> one you are used to riding. I'd have to disagree if you think a light bike really makes you
> any faster.

It does. I don't know how much faster; but it is a factor.

> I'd rather have a stiff no nonsense frame that I know is going to last, even if it's heavy.

Speed and bike longevity are two completely different criteria.

> The bike I ended up getting is on the heavy side (30+ pounds) but feels very light underfoot. The
> frame is heavy but stout.

If that's what you prefer, then that's great.

> I'm a believer in cheap used bikes. There are legions of good used bikes which need new owners.

Agreed. The vast majority of riders are not, and never will be, racers. Used bikes can be great. I
will say that if you rely upon a bike shop for repairs, a used bike may not be worth messing with.
You can rack up a pretty big bill on repairs that will likely eat up any difference in price. (I'm
speaking of low- to mid-range bikes here.)

Have a great time riding your new bike. I'm glad that you found one that you enjoy. That's the most
important thing.

-Barry

 

[Mark H.]

Greetings!

As a newbie rider, belonging to a local club and going out on group training rides, I've noticed
that the ride leaders generally stand when climbing. I find that standing takes too much out of my
quads, so I sit and concentrate on relaxing my body and utilizing my hams and spin to get up the
hill. I also try to minimize the side-to side bike motion to keep the effort concentrated on forward
motion. Maybe if I stood and had a little bike motion going, I'd "feel" better, but I don't think
that would translate to more efficient climbing, rather that I'd just feel like it was. As my
fitness progresses, my style may very well change, but, for now, my climbing is improving.

On the other hand: Many years ago, when skateboarding, I and my friends would start our skateboards
from a dead stop by inducing side-to-side "whip," propelling us forward increasingly faster. I
suspect that fitter cyclists, standing, can induce the same "whipping" motion on their bikes,
thereby propelling themselves up a hill with less effort. A lighter bike may well allow them to get
this rhythm going easier. Is this what the original poster was referring to?

Mark H.

"Mike S." <mikeshaw2@coxDOTnet> wrote in message news:LKroa.2988$366.2843@fed1read06...
>
> "Andrew Bradley" <[email protected]> wrote in message
> news:[email protected]...
> >
> > Tim McNamara :
> >
> > > People stand to sprint in order to use their weight on the pedals, not because there's
> > > "significant extra power" available from the upper body.
> >
> > Standing does of course make more weight available to push against and
the
> > arms provide extra reaction force too. But it is still strange that
> riders
> > will sprint out of the saddle on big gears rather than sit and spin at
> the
> > sort of revs that give max power on an ergometer (which I believe isn't limited by reaction
> > force).
> >
> > The arm-work is not negligible and the legs work in a different way to
> when
> > you are seated which could also affect max power.
> >
> > Do you think out-of-saddle riding is no more powerful than seated
riding?
> >
> > > Watch the pros race. Many of the top sprinters do most of their sprint sitting down; this is
> > > even more apparent in track sprinters. Standing for 200-300 meters of all-out sprinting is not
> > > effective for most riders (Abdujaparov being a notable exception). Amateurs tend to be more
> > > likely to sprint standing, but the sprints tend to only be 50-100 meters long.
> >
> > Don't know which pros you're watching and your amateurs must be
> schoolboys.
> > I'm only talking about the maximal effort part not the wind up.
> >
> > Trackies don't count since they don't have gears. You have to sit at
those
> > RPM. And when they ride the road, they do like everybody else.
> >
> At least THIS trackie does...
>
> Mike

 

[Tim McNamara]

In article <vJFoa.546287$L1.159650@sccrnsc02>,
"B. Sanders" <[email protected]> wrote:

> Changing tires changes handling. Changing tire size always changes handling noticeably (IME).

Changing tire size changes trail. That can be easily noticed.

 

[David L. Johnso]

On Sun, 20 Apr 2003 21:08:00 +0000, Tim McNamara wrote:

>> Changing tires changes handling. Changing tire size always changes handling noticeably (IME).
>
> Changing tire size changes trail. That can be easily noticed.

That is a pretty small change. The trail will increase, for each mm of tire height (less than the
tire diameter change, but close enough) by z/x mm, where z=trail with smaller tire, and x = distance
from hub to ground of smaller tire. Since x is on the order of 340mm, and x is on the order of 60 or
so mm (guessing, there), you are talking about .2mm per mm of tire. So, going from a typical 23mm
tire to a 28mm (as large as many bikes can handle) gives you 1mm or less of extra trail. That is
pretty much a princess-and-the-pea difference.

I suggest that you would feel a lot more the lower pressure, greater damping, and even the wider
shoulder of the tire.

--

David L. Johnson

__o | If all economists were laid end to end, they would not reach a _`\(,_ | conclusion. --
George Bernard Shaw (_)/ (_) |

 

[Peter Cole]

> What I was saying is that during rapid acceleration, a light bike is going to be faster.

But, bikes don't accelerate fast.

> This is especially true for out-of-the saddle riding, particularly when climbing hills. I submit
> that while the difference in the rider + bike system differs very little (between heavier and
> ligher bikes), the effect of riding a light(er) bike up hills is an actual increase in climbing
> speed, due to the ease of "tossing" the bike, and less energy lost in the riding technique due to
> the bike's inertia. I call this property "flickability."

"Flickability" is a term frequently used in mountain biking, where bikes are tossed around and over
trail obstacles. It's not used in road biking, and doesn't have any bearing on hill climbing.

> There may be some additional benefit to having lighter wheels, too; due to a reduced energy loss
> from fighting the rotational inertia of the wheels as their attitude is changed constantly (while
> tossing the bike from side to side).

The "rotational inertia" argument, more commonly called the "rotating mass", is a well known ploy to
sell boutique wheels. That horse has been beaten to death on these forums.

> This also points to the likelihood that smaller wheels are ideal for fast bikes, since they are
> lighter and thus have less rotational inertia than larger wheels. Alex Moulton believed this to be
> true, as have many others.

This is like the 650 wheel tri-geek thing, another fad-to-nowhere.

> I have not conducted a scientific test of my hypotheses. Yet.

How are you planning to do that?

 

[Tim McNamara]

In article <[email protected]>, "David L. Johnson" <[email protected]> wrote:

> On Sun, 20 Apr 2003 21:08:00 +0000, Tim McNamara wrote:
>
> >> Changing tires changes handling. Changing tire size always changes handling noticeably (IME).
> >
> > Changing tire size changes trail. That can be easily noticed.
>
> That is a pretty small change. The trail will increase, for each mm of tire height (less than the
> tire diameter change, but close enough) by z/x mm, where z=trail with smaller tire, and x =
> distance from hub to ground of smaller tire. Since x is on the order of 340mm, and x is on the
> order of 60 or so mm (guessing, there), you are talking about .2mm per mm of tire. So, going from
> a typical 23mm tire to a 28mm (as large as many bikes can handle) gives you 1mm or less of extra
> trail. That is pretty much a princess-and-the-pea difference.

Using the formula for trail in Whitt and Wilson:

t=d(1/sinH*((cosH/2)-(y/d)) where t = trail d = diameter of wheel H = head angle in degrees y =
fork offset

for my bike with a 73.5 degree head angle and fork with 40 mm offset (Ritchey Road), then for the
tire sizes on the left column:

600 x y d H trail 18 40 658 73.5 57.45 20 40 662 73.5 58.05 23 40 668 73.5 58.94 25 40 672 73.5
59.53 28 40 678 73.5 60.42 32 40 686 73.5 61.60

The difference (using idealized tire sizes because I don't feel like running downstairs into the
basement to measure them with a caliper) between a 700 x 23 and a 700 x 28 is 1.48 mm.

> I suggest that you would feel a lot more the lower pressure, greater damping, and even the wider
> shoulder of the tire.

I find the difference quite noticeable, especially in weaving motions such as S-turns and chicanes.
I run the same pressure in my 700 x 23 and my 700 x 28 tires (120 psi) habitually rather than
because it's a good idea. The shape of the contact patch between the smaller and wider tires is
somewhat different and presumably therefore the cornering feel ought to be somewhat different.

What I don't know is whether any one of these changes (trail, contact patch, damping, tire profile)
is sufficient to explain the difference in road feel. With the smaller tires that I used to use when
racing (Michelin Synergic 700 x 23), the bike leaned in and out of corners more easily and was very
easily manuevered in weaving motions such as slaloming though the dashed lane lines on roads. With
the larger tires (Continental Ultra 2000 700 x 28), the bike feels overly stable and rather
resistant to such manuevers.

So, to commit a tautology, either it's all in my head (always a possibility) or these small
incremental changes actually have a noticeable effect. Whether it's any one factor (I think I've
isolated out tire pressure) such as change in trail, change in contact patch, change in tire width
or all in combination, I do not know.