New rear tire installed...

C.J.Patten said:

Wow.

I just got back from my first ride after installing a touring tire on the
rear wheel of my bike.
(20" rim folder) What a difference!

Old tire: Innova 54-406 (20"x1.95) knobby (or "semi" at least)
New tire: Vee-Rubber 47-406 (20"x1.75"😉 tourer

I just rode 10km averaging 3km/hr faster than usual - and I don't feel
nearly as tired as I did on the old tire!

How much of this is just psychological? Surely not all of it...

Boy was that fun!

😄

HUGE thank you to Sheldon Brown - I was reading either a post or a page from
the Harris Cyclery discussing the merits of same/different front/rear tires.
I left the semi-knobby on the front wheel for now and I'm loving the
handling of the bike. Nice and crisp in corners but so much faster...

On the topic of "found while riding" - aside from getting a bit closer to
enlightenment, I also found a lone platform pedal on my ride today...

Chris

Dear Chris,

The psychological improvement (if any) should fade within
two weeks, so you can watch your times for that.

Meanwhile, you can go here, pick metric units, and fiddle
with theoretical recumbent styles and front/rear tire
choices:

http://www.kreuzotter.de/english/espeed.htm

Using the defaults, I picked a short wheelbase equipped for
commuting (a middling recumbent), stuck a pair of offroad
1.75" tires (the worst knobbies), and got 28.7 km/h.

When I swapped the rear knobby for a wide high pressure
slick, the speed improved to 29.6 km/h.

Stick a high pressure slick on the front, and the speed
improves to 30.8 km/h.

Now add a 3.5 km/h headwind, and the speed drops back to the
original 28.7 km/h. Very few of us can notice a 2.2 mph
headwind change--a very minor wind speed change can blow
away a rolling resistance advantage, which is why
calculators and wind tunnel tests are used more than
attempts at repeated practical runs.

One possible fudge factor: the calculator may not address
the horrible wind drag of impressive knobs, which may be
just as bad as their increased rolling resistance. The FAQ
for the page shows that the increased drag of pedal cadence
is noted, but I've found nothing about the relative
aerodynamic drag of miniature rhino horns versus smooth
tread.

Carl Fogel

C.J.Patten said:

How much of this is just psychological? Surely not all of it...

Some new carbon fiber insoles could surely add another 3kph?

:P

I wouldn't doubt your claims--though new gear does tend to make you happy
and thus ride better--rubber is one of those things that does make a
difference. No more knobby squirm to waste energy, that's a good thing.

OH! Speaking of gear(s) - I was averaging one gear *higher* than I've been
using over the past month. On my ride this morning, I felt like I was
struggling in 14th gear - tonight, I was in 15th for most of the ride.

The only thing niggling at me now is I have to start looking at buying a
larger front chainring! (44 now...maybe a 54 next?)

I found the source page I was reading last night:
http://www.sheldonbrown.com/tires.html#width

I love your term: "squirm" Very fitting... 8D

Chris

"maxo" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

C.J.Patten said:

How much of this is just psychological? Surely not all of it...

Some new carbon fiber insoles could surely add another 3kph?

:P

I wouldn't doubt your claims--though new gear does tend to make you happy
and thus ride better--rubber is one of those things that does make a
difference. No more knobby squirm to waste energy, that's a good thing.

Very cool Carl. Thanks for the info - and detailed test results!
I'm using a "wedgie" bike - a folding model with 20" wheels - that website
is fantastic! I'll bookmark that.

One thing on my mind: I'm VERY out of shape. I notice even slight changes
during a ride.

When I have a headwind (tonight's wind was ~4mph) I experience a noticable
drag versus cross or downwind. My route takes me in all directions so I get
this from all angles.

The switch to the slick seemed just as pronounced a difference as the wind
direction.

Good suggestion - I'll wait a couple of weeks and see what comes of this. 😉

Cheers!
Chris

p.s. now you got me wanting a WindCheetah recumbant. 8p

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Dear Chris,

The psychological improvement (if any) should fade within
two weeks, so you can watch your times for that.

Meanwhile, you can go here, pick metric units, and fiddle
with theoretical recumbent styles and front/rear tire
choices:

http://www.kreuzotter.de/english/espeed.htm

Using the defaults, I picked a short wheelbase equipped for
commuting (a middling recumbent), stuck a pair of offroad
1.75" tires (the worst knobbies), and got 28.7 km/h.

When I swapped the rear knobby for a wide high pressure
slick, the speed improved to 29.6 km/h.

Stick a high pressure slick on the front, and the speed
improves to 30.8 km/h.

Now add a 3.5 km/h headwind, and the speed drops back to the
original 28.7 km/h. Very few of us can notice a 2.2 mph
headwind change--a very minor wind speed change can blow
away a rolling resistance advantage, which is why
calculators and wind tunnel tests are used more than
attempts at repeated practical runs.

One possible fudge factor: the calculator may not address
the horrible wind drag of impressive knobs, which may be
just as bad as their increased rolling resistance. The FAQ
for the page shows that the increased drag of pedal cadence
is noted, but I've found nothing about the relative
aerodynamic drag of miniature rhino horns versus smooth
tread.

Carl Fogel

C.J.Patten said:

Wow.

I just got back from my first ride after installing a touring tire on the
rear wheel of my bike.
(20" rim folder) What a difference!

Old tire: Innova 54-406 (20"x1.95) knobby (or "semi" at least)
New tire: Vee-Rubber 47-406 (20"x1.75"😉 tourer

I just rode 10km averaging 3km/hr faster than usual - and I don't feel
nearly as tired as I did on the old tire!

How much of this is just psychological? Surely not all of it...

Dunno in your case, but swapping from knobbies to slicks on one of the
bikes here made a perceptible difference in the coasting range coming
off one of the overpasses nearby. That bike doesn't have a comp, so I
don't know what the speeds were.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

C.J.Patten said:

Very cool Carl. Thanks for the info - and detailed test results!
I'm using a "wedgie" bike - a folding model with 20" wheels - that website
is fantastic! I'll bookmark that.

One thing on my mind: I'm VERY out of shape. I notice even slight changes
during a ride.

When I have a headwind (tonight's wind was ~4mph) I experience a noticable
drag versus cross or downwind. My route takes me in all directions so I get
this from all angles.

The switch to the slick seemed just as pronounced a difference as the wind
direction.

Good suggestion - I'll wait a couple of weeks and see what comes of this. 😉

Cheers!
Chris

p.s. now you got me wanting a WindCheetah recumbant. 8p

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Dear Chris,

The psychological improvement (if any) should fade within
two weeks, so you can watch your times for that.

Meanwhile, you can go here, pick metric units, and fiddle
with theoretical recumbent styles and front/rear tire
choices:

http://www.kreuzotter.de/english/espeed.htm

Using the defaults, I picked a short wheelbase equipped for
commuting (a middling recumbent), stuck a pair of offroad
1.75" tires (the worst knobbies), and got 28.7 km/h.

When I swapped the rear knobby for a wide high pressure
slick, the speed improved to 29.6 km/h.

Stick a high pressure slick on the front, and the speed
improves to 30.8 km/h.

Now add a 3.5 km/h headwind, and the speed drops back to the
original 28.7 km/h. Very few of us can notice a 2.2 mph
headwind change--a very minor wind speed change can blow
away a rolling resistance advantage, which is why
calculators and wind tunnel tests are used more than
attempts at repeated practical runs.

One possible fudge factor: the calculator may not address
the horrible wind drag of impressive knobs, which may be
just as bad as their increased rolling resistance. The FAQ
for the page shows that the increased drag of pedal cadence
is noted, but I've found nothing about the relative
aerodynamic drag of miniature rhino horns versus smooth
tread.

Carl Fogel

Dear Chris,

It's annoying, but many initial improvements turn out to
involve a fair amount of the new-toy syndrome--we pay more
attention to what we're doing when we first play with our
new toys, and consequently pedal more steadily than we
normally do.

We often feel a tremendous improvement with a slightly
lighter bike and even find our times reflecting some of this
sensation--but the physics involved indicates that the
actual improvement due to the weight savings is scarcely
measurable.

Still, there's nothing wrong with trying new toys to keep
our interest up and the manufacturers solvent.

And your switch to a slick instead of a knobby should indeed
improve your time slightly because of reduced rolling
resistance, slightly because of reduced wind drag, and
slightly because you rode off on your test ride more
interested.

As for the wind, there's regrettably a good deal of drag in
a crosswind.

Jobst Brandt's theory and testing suggest that at reasonable
biking speeds, a reasonable wind doesn't go neutral until
it's around 10 degrees behind the rider:

http://www.sheldonbrown.com/brandt/wind.html#milliken

For recumbents, here's another speed calculator to play
with, which has some tire tables:

http://www.recumbents.com/wisil/simul/HPV_Simul.asp

There are so many variables and so many assumptions in these
calculators that they're unlikely to agree perfectly, but in
general they give a fairly good idea of what's going on.

Fooling around with different weights, tires, winds, and
positions will give a notion of what kind of effects can
reasonably be expected, as opposed to what the wicked
marketing departments claim and virtuous riders mistakenly
think.

Carl Fogel