Dear Jobst, Left-Hand Chain-Drive Details

[Terry Morse]

David Damerell wrote:

> I've even seen people on pseudo-MTBs _front_ shifting at lights, which is clearly pointless
> because they can't push hard during a front shift.

Front shifting isn't completely pointless. I'll do it sometimes when I want a fast jump across the
intersection. I get up to about 20mph before needing to front shift, which is fast enough to not
worry about pushing hard.
--
terry morse Palo Alto, CA http://www.terrymorse.com/bike/

 

[Andrey]

> I doubt that anyone would advise that gear for anything but closing a gap, downhill or with a
> strong tailwind. Just because they are available doesn't make them useful gears. In fact riders
> who think pedaling at speeds over 30mph when descending is useful are fooling themselves. You can
> compute the extra power required to increase speed from 30 to 31mph and see that it is a huge
> jump. I often coast by people who think that just because they have an 11t sprocket that it will
> help them go faster.

I think you not really Jobst Brandt, because you make such a gross error declaration.

> > Asking questions is often better than avoiding them, don't you agree? For all I know, you may
> > have a sound explanation for the notion that using a single high gear is as good as shifting up
> > through a range in starting out on a level ride.
>
> Those who do it know why. The continuity of effort is far more important than changing rate and
> force on the pedals. When climbing, shifting is one of the most difficult decisions because
> regardless of which direction is needed, the change in cadence and force hurts. Neither of them
> want to have a step function. Shifting invariably slows speed if it is done when near the limit
> of effort.

When climbing, Power Output is even more needed to monitor, than on flat road. You "may-be-shifting-
problems" announcements are ridiculous. You really need the Polar with power meter. You will see,
that maximum transfered to wheel power is in limited 60-110 cadence range, so to start at high gear
is inefficient.

>
> > I hope to get it before the 25th.
>
> Santa can't ride worth a damn. To heavy.
>
> Jobst Brandt [email protected]

 

[Dave Kahn]

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

> Those who do it know why. The continuity of effort is far more important than changing rate and
> force on the pedals. When climbing, shifting is one of the most difficult decisions because
> regardless of which direction is needed, the change in cadence and force hurts. Neither of them
> want to have a step function. Shifting invariably slows speed if it is done when near the limit
> of effort.

These days there are a lot of utility riders on mountain bikes and hybrids with a huge range of
(mostly low) gears available. I notice many of them starting out from traffic lights in absurdly low
gears and clearly riding at close to maximum effort. Although their pedalling looks Chaplinesque
they do in fact have impressive acceleration over about the first 5 to 10 yards, but as they move up
through the ratios the effort tells and within about 30 yards they start to drop back.

That said, the track bike set up with a left handed freewheel and an almost unscrewed fixed is an
ingenious idea for providing one fully automatic gear change early in the ride. I don't think you
could just rule out the idea that it might provide an advantage without at least testing it. The
inital acceleration at least has to be better. The question is whether the cost of the gear change
and the slight increase in weight wipe out that initial advantage. Whether it's track legal is
another matter.

--
Dave...

 

[Scott Hendricks]

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

> I doubt that anyone would advise that gear for anything but closing a gap, downhill or with a
> strong tailwind. Just because they are available doesn't make them useful gears. In fact riders
> who think pedaling at speeds over 30mph when descending is useful are fooling themselves. You can
> compute the extra power required to increase speed from 30 to 31mph and see that it is a huge
> jump. I often coast by people who think that just because they have an 11t sprocket that it will
> help them go faster.
>
>
> Jobst Brandt [email protected]

Don't forget to add in the effect of gravity to the power requirement equation. While it may
require a lot of power to increase from 30 to 31 mph on the flats, it's not that hard to do it on
a downhill.

I've experienced what you describe on very steep downhills where pedaling didn't seem to help
much, but I've also been on the rivet in the 53/12 on a moderate downhill trying to keep up with
folks in their
53/11. Coasting damn sure wouldn't have made it easier! ;->

Scott

 

[Terry Morse]

Carl Fogel wrote:

> I expect that a serious rider would:
>
> a) use lower gears than 53 x 11
> b) spin higher cadences than 52 to 66 rpm
> c) go much farther than 15 miles per day
> d) pedal much faster than 20-25mph on flats
>
> But I don't know why lower gears and brisker pedalling work better for such riders. I'm so
> sluggish that it seems to me that they must be doing more work, raising their legs faster and so
> many more times to cover the same mile.
>
> If you have a higher-cadence explanation, I hope that you can dumb it down for me. Perhaps there's
> a slow-twitch diesel in my family tree?

"Serious riders" spin higher cadences to delay the onset of muscle fatigue. The main cause of muscle
fatigue on a longer ride (2+ hours) is the depletion of muscle glycogen, the fuel that's burned by
the leg muscles. The lower the peak muscle effort, the lower the rate of muscle glycogen depletion.
When glycogen stores are gone, a rider can't produce nearly as much power and is forced to slow
down. Since higher cadences require lower peak muscle effort, one can ride longer at the same power
output before depleting glycogen.

A higher cadence requires a somewhat greater aerobic effort, but this is much more preferable to
muscle fatigue.

--
terry morse Palo Alto, CA http://www.terrymorse.com/bike/

 

[Jobst Brandt]

Jeff Wills writes:

> Modern Top Fuel engines produce between 5,000 and 6,000 horsepower... and there's enormous amounts
> of clutch slip in the first third of the run. If you watch video of a TF start, you can see the
> puffs of carbon fiber dust from the clutch.

> *Of course* it's for suppressing wheel slip- but clutch slip also >
allows the engine to make maximum power while not smoking the tires > (as you said) or setting up
resonance in the sidewalls (tire shake).

> Here's the output from a Top Fuel data logger:

http://www.plr.nu/images/graph.jpg

> the black line show engine rpm and the dark blue line shows speed. It's pretty apparent that
> engine RPM is nearly constant while the vehicle is accelerating. With a single gear ratio, the
> only way to accomplish this is through clutch slip.

That's a lot of power to be throwing off through a clutch. I'm not privy to what they are doing with
5000hp but throwing that out as heat somewhere is difficult. You could make a lot of steam with
that. What is apparent from the graphs is that acceleration is relatively constant and that takes
similarly increasing power. I can imagine a torque converter involved but blowing away most of the
power as slip in a clutch exceeds my understanding of what goes on. It does require half the energy
to be converted to heat. That's 5000hp*4.4sec/2 = 2279KWH or a lot of heat, more than can be
contained in a small box without emitting flames. That's 1864KW being scrubbed off at the start.

Jobst Brandt [email protected]

 

[Carl Fogel]

Terry Morse <[email protected]> wrote in message news:<[email protected]>...

[snip Fogel]

> "Serious riders" spin higher cadences to delay the onset of muscle fatigue. The main cause of
> muscle fatigue on a longer ride (2+ hours) is the depletion of muscle glycogen, the fuel that's
> burned by the leg muscles. The lower the peak muscle effort, the lower the rate of muscle glycogen
> depletion. When glycogen stores are gone, a rider can't produce nearly as much power and is forced
> to slow down. Since higher cadences require lower peak muscle effort, one can ride longer at the
> same power output before depleting glycogen.
>
> A higher cadence requires a somewhat greater aerobic effort, but this is much more preferable to
> muscle fatigue.

Dear Terry,

Aha!

So it's not a matter of any mechanical leverage, but more a matter of how soon a particular kind of
effort leaves the rider tired.

Your explanation suggests why I've been so puzzled. My daily ride with my adagio cadence lasts only
about 45 minutes, so I've never found out what happens after 120 minutes.

If I'm following you, I'd last a lot longer at a higher cadence, even though it would take a
slightly higher level of effort.

I appreciate how nicely you explained the situation and must try to lure you out on other subjects.

Thanks!

Carl Fogel

 

[Terry Morse]

Carl Fogel wrote:

> If I'm following you, I'd last a lot longer at a higher cadence, even though it would take a
> slightly higher level of effort.

You got the point exactly.

By the way, 20-25 mph without drafting is a pretty spirited pace on the flats.
--
terry morse Palo Alto, CA http://www.terrymorse.com/bike/

 

[Tom Sherman]

Jeff Wills wrote:
>
> Here's the output from a Top Fuel data logger: http://www.plr.nu/images/graph.jpg the black line
> show engine rpm and the dark blue line shows speed. It's pretty apparent that engine RPM is nearly
> constant while the vehicle is accelerating. With a single gear ratio, the only way to accomplish
> this is through clutch slip.

Not true in this case. The tires used on Top Fuel and Funny Car dragsters are of special sidewall
construction that allows the tire diameter to increase (and frontal area to decrease) as the
rotational speed increases. Inflation pressures are also low (the tires are held to the rims with
bead-locks) which allows for a smaller diameter at low speeds.

Changes in the diameter of bicycle tires with rotational speed are of course so small as to be
inconsequential.

Tom Sherman - 41 N, 90 W

 

[Ryan Cousineau]

In article <[email protected]>,
[email protected] wrote:

> Jeff Wills writes:
>
> > Modern Top Fuel engines produce between 5,000 and 6,000 horsepower... and there's enormous
> > amounts of clutch slip in the first third of the run. If you watch video of a TF start, you can
> > see the puffs of carbon fiber dust from the clutch.
>
> > *Of course* it's for suppressing wheel slip- but clutch slip also >
> allows the engine to make maximum power while not smoking the tires > (as you said) or setting up
> resonance in the sidewalls (tire shake).
>
> > Here's the output from a Top Fuel data logger:
>
> http://www.plr.nu/images/graph.jpg
>
> > the black line show engine rpm and the dark blue line shows speed. It's pretty apparent that
> > engine RPM is nearly constant while the vehicle is accelerating. With a single gear ratio, the
> > only way to accomplish this is through clutch slip.
>
> That's a lot of power to be throwing off through a clutch. I'm not privy to what they are doing
> with 5000hp but throwing that out as heat somewhere is difficult. You could make a lot of steam
> with that. What is apparent from the graphs is that acceleration is relatively constant and that
> takes similarly increasing power. I can imagine a torque converter involved but blowing away
> most of the power as slip in a clutch exceeds my understanding of what goes on. It does require
> half the energy to be converted to heat. That's 5000hp*4.4sec/2 = 2279KWH or a lot of heat, more
> than can be contained in a small box without emitting flames. That's 1864KW being scrubbed off
> at the start.

http://www.nhra.com/anatomy/topfuel.htm

Would you believe 1000-degree F clutches? 5 discs, 10" diameter, and titanium bell housings.

And all that noise, noise, noise noise!

My father pointed out something interesting about traffic noise the other day: most of it is from
heavy truck transmissions.

I started paying attention during my commute, and he was right. Modern cars are mostly eerily silent
except under heavy loads. The main sound is tire noise, though I did get passed by an accelerating
Honda with a modified intake system. The intake honk as it approached from behind was louder than
the exhaust note as it passed ahead.

The truck noise is a very distinct mechanical clatter, not apparently from the exhaust, and (except
for trucks using their retarder brakes) the loudest sound on the road.

Power corrupts drivetrains,
--
Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club

 

[Carl Fogel]

Ryan Cousineau <[email protected]> wrote in message news:<[email protected]>...
> In article <[email protected]>, [email protected] wrote:
>
> > Jeff Wills writes:
> >
> > > Modern Top Fuel engines produce between 5,000 and 6,000 horsepower... and there's enormous
> > > amounts of clutch slip in the first third of the run. If you watch video of a TF start, you
> > > can see the puffs of carbon fiber dust from the clutch.
>
> > > *Of course* it's for suppressing wheel slip- but clutch slip also >
> > allows the engine to make maximum power while not smoking the tires > (as you said) or setting
> > up resonance in the sidewalls (tire shake).
> >
> > > Here's the output from a Top Fuel data logger:
> >
> > http://www.plr.nu/images/graph.jpg
> >
> > > the black line show engine rpm and the dark blue line shows speed. It's pretty apparent that
> > > engine RPM is nearly constant while the vehicle is accelerating. With a single gear ratio, the
> > > only way to accomplish this is through clutch slip.
> >
> > That's a lot of power to be throwing off through a clutch. I'm not privy to what they are doing
> > with 5000hp but throwing that out as heat somewhere is difficult. You could make a lot of steam
> > with that. What is apparent from the graphs is that acceleration is relatively constant and that
> > takes similarly increasing power. I can imagine a torque converter involved but blowing away
> > most of the power as slip in a clutch exceeds my understanding of what goes on. It does require
> > half the energy to be converted to heat. That's 5000hp*4.4sec/2 = 2279KWH or a lot of heat, more
> > than can be contained in a small box without emitting flames. That's 1864KW being scrubbed off
> > at the start.
>
> http://www.nhra.com/anatomy/topfuel.htm
>
> Would you believe 1000-degree F clutches? 5 discs, 10" diameter, and titanium bell housings.
>
> And all that noise, noise, noise noise!
>
> My father pointed out something interesting about traffic noise the other day: most of it is from
> heavy truck transmissions.
>
> I started paying attention during my commute, and he was right. Modern cars are mostly eerily
> silent except under heavy loads. The main sound is tire noise, though I did get passed by an
> accelerating Honda with a modified intake system. The intake honk as it approached from behind was
> louder than the exhaust note as it passed ahead.
>
> The truck noise is a very distinct mechanical clatter, not apparently from the exhaust, and
> (except for trucks using their retarder brakes) the loudest sound on the road.
>
> Power corrupts drivetrains,

Dear Ryan,

Interesting page.

"A Top Fuel chassis . . . is fabricated from 300 feet of 4130 chromoly tubing . . . "

Hey, just like my bike!

" . . . and costs between $30,000 and $40,000"

Well, almost like my bike.

"All Top Fuel cars run a standard rear-gear ratio of 3.20-1."

Fixed-gear rules!

"Top Fuel dragsters must weigh a minimum of 2,025 pounds and may not have a wheelbase that
measures more than 300 inches or fewer than 180 inches."

Just as fussy as the UCI.

"A complete fire-resistant driving suit, gloves, helmet, and 360-degree neck collar must be worn."

Better not let the horrified-by-helmets crowd see this.

"The fat Goodyear slicks on back are 18 inches wide and nearly 10 feet in circumference
(118 inches)."

High-wheeler heaven! And slick tread, just like Jobst wants. Plus there's only one brand, so the
marketing hype must be minimal.

"The rear-brake rotors measure 10 3/4 or 11 1/2 inches in diameter and are made from either steel
or carbon fiber, activated via a hand lever in the cockpit, and utilized only on the rear tires."

Rear-only weird-operating coaster brakes!

"Two types of front tires are used -- small airplane-style tires, for quicker reaction times, and
larger, bicycle-size units, for better elapsed times."

When dragsters really want to move fast, they know what kind of technology to turn to!

Carl Fogel

 

[Jobst Brandt]

Ryan Cousineau writes:

> http://www.nhra.com/anatomy/topfuel.htm

> Would you believe 1000-degree F clutches? 5 discs, 10" diameter, and titanium bell housings.

Temperature is not power. We know that disc brakes on cars glow yellow but that is no way near
5000hp. Citing temperature as a proof of power dissipation makes me think you aren't talking about
the same problem.

> And all that noise, noise, noise noise!

> My father pointed out something interesting about traffic noise the other day: most of it is from
> heavy truck transmissions.

If you believe that you'll believe anything. The major source of noise is tire to road displacement
of air. It is a rushing noise much like storm surf off in the distance. Who invents these tales???
Heavy truck transmissions, wow!

> I started paying attention during my commute, and he was right. Modern cars are mostly eerily
> silent except under heavy loads. The main sound is tire noise, though I did get passed by an
> accelerating Honda with a modified intake system. The intake honk as it approached from behind was
> louder than the exhaust note as it passed ahead.

I don't know on what planet you live but that is a nice story unrelated to traffic noise. Maybe you
haven't noticed sound walls along highways. These are not in response to howling truck
transmissions. The are used even on roads that allow no trucks.

> The truck noise is a very distinct mechanical clatter, not apparently from the exhaust, and
> (except for trucks using their retarder brakes) the loudest sound on the road.

What noise are you talking about???

Jobst Brandt [email protected]

 

[Jeff Wills]

[email protected] wrote in message
news:<[email protected]>... <snip>
> That's a lot of power to be throwing off through a clutch. I'm not privy to what they are doing
> with 5000hp but throwing that out as heat somewhere is difficult. You could make a lot of steam
> with that. What is apparent from the graphs is that acceleration is relatively constant and that
> takes similarly increasing power. I can imagine a torque converter involved but blowing away
> most of the power as slip in a clutch exceeds my understanding of what goes on. It does require
> half the energy to be converted to heat. That's 5000hp*4.4sec/2 = 2279KWH or a lot of heat, more
> than can be contained in a small box without emitting flames. That's 1864KW being scrubbed off
> at the start.
>
> Jobst Brandt [email protected]

Well, all of this exceeds *my* understanding by a wide margin... but drag racers are evidently still
in possession of their souls, so *something* non-magical is happening.

If you're around, here's an event for you to attend:
http://www.infineonraceway.com/major_events/394211.html Note that they're claiming 8,000
horsepower... so all of your calculations may need to be revised.

Jeff

 

[Ryan Cousineau]

In article <[email protected]>,
[email protected] wrote:

> Ryan Cousineau writes:
>
> > http://www.nhra.com/anatomy/topfuel.htm
>
> > Would you believe 1000-degree F clutches? 5 discs, 10" diameter, and titanium bell housings.
>
> Temperature is not power. We know that disc brakes on cars glow yellow but that is no way near
> 5000hp. Citing temperature as a proof of power dissipation makes me think you aren't talking about
> the same problem.

Well, you earlier mentioned that the numbers on the power dissipation indicated that something must
be close to melting point, if the clutches were indeed slipping so much. I found a number (from the
NHRA, who one hopes is able to get roughly accurate data) giving an idea of what the operating
temperatures of these clutches were. Indeed, I even told you how big they are: make some rough
guesses as to material and thickness, and I'll bet you could come up with a close-enough guess as to
the amount of power this system turns into heat that gets soaked up by the clutch. Any remaining
power presumably turns into noise or acceleration.

> > And all that noise, noise, noise noise!
>
> > My father pointed out something interesting about traffic noise the other day: most of it is
> > from heavy truck transmissions.
>
> If you believe that you'll believe anything. The major source of noise is tire to road
> displacement of air. It is a rushing noise much like storm surf off in the distance. Who invents
> these tales??? Heavy truck transmissions, wow!

Well, I should be more precise: the loudest single source of noise was clearly coming from each
truck, and was definitely mechanical (as opposed to from the tires) in nature. The cars were most of
the total noise, because there were more of them, but the car noise is mostly tire noise (with a few
exceptions). I shan't misrepresent my dad's claim any further: his key point was that the
transmission in a big truck is bearing considerable loads and we know it has a fair amount of
inefficiency. I found an online claim of 95-98% efficiency for the drivetrain. For a 500 hp engine,
that means up to 25 hp lost by the drivetrain (and that sounds suspiciously low to me). That's not
all turned into heat, and that's a lot of noise.

> > I started paying attention during my commute, and he was right. Modern cars are mostly eerily
> > silent except under heavy loads. The main sound is tire noise, though I did get passed by an
> > accelerating Honda with a modified intake system. The intake honk as it approached from behind
> > was louder than the exhaust note as it passed ahead.
>
> I don't know on what planet you live but that is a nice story unrelated to traffic noise. Maybe
> you haven't noticed sound walls along highways. These are not in response to howling truck
> transmissions. The are used even on roads that allow no trucks.

Really? This particular road was a non-freeway commuter chute with considerable truck traffic and
peak speeds of around 70 km/h (posted 50, but you know how that goes).

All the traffic is noisy, and certainly the tire noise was quite distinct. But the truck noise
cut through.

> > The truck noise is a very distinct mechanical clatter, not apparently from the exhaust, and
> > (except for trucks using their retarder brakes) the loudest sound on the road.
>
> What noise are you talking about???

Abre los ... er... what's Spanish for "ears" ... oídos?

--
Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club

 

[meb]

Originally posted by Ryan Cousineau
In article <[email protected]>,
[email protected] wrote:

> Jeff Wills writes:
>
> > Modern Top Fuel engines produce between 5,000 and 6,000 horsepower... and there's enormous
> > amounts of clutch slip in the first third of the run. If you watch video of a TF start, you can
> > see the puffs of carbon fiber dust from the clutch.
>
> > *Of course* it's for suppressing wheel slip- but clutch slip also >
> allows the engine to make maximum power while not smoking the tires > (as you said) or setting up
> resonance in the sidewalls (tire shake).
>
> > Here's the output from a Top Fuel data logger:
>
> http://www.plr.nu/images/graph.jpg
>
> > the black line show engine rpm and the dark blue line shows speed. It's pretty apparent that
> > engine RPM is nearly constant while the vehicle is accelerating. With a single gear ratio, the
> > only way to accomplish this is through clutch slip.
>
> That's a lot of power to be throwing off through a clutch. I'm not privy to what they are doing
> with 5000hp but throwing that out as heat somewhere is difficult. You could make a lot of steam
> with that. What is apparent from the graphs is that acceleration is relatively constant and that
> takes similarly increasing power. I can imagine a torque converter involved but blowing away
> most of the power as slip in a clutch exceeds my understanding of what goes on. It does require
> half the energy to be converted to heat. That's 5000hp*4.4sec/2 = 2279KWH or a lot of heat, more
> than can be contained in a small box without emitting flames. That's 1864KW being scrubbed off
> at the start.

http://www.nhra.com/anatomy/topfuel.htm

Would you believe 1000-degree F clutches? 5 discs, 10" diameter, and titanium bell housings.

And all that noise, noise, noise noise!

My father pointed out something interesting about traffic noise the other day: most of it is from
heavy truck transmissions.

I started paying attention during my commute, and he was right. Modern cars are mostly eerily silent
except under heavy loads. The main sound is tire noise, though I did get passed by an accelerating
Honda with a modified intake system. The intake honk as it approached from behind was louder than
the exhaust note as it passed ahead.

The truck noise is a very distinct mechanical clatter, not apparently from the exhaust, and (except
for trucks using their retarder brakes) the loudest sound on the road.

Power corrupts drivetrains,
--
Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club

When did drag racing switch to slip clutches?

I suspect it has been since the early 90’s.

This graph shows a relatively smooth acceleration, no 8G launch spike.

The near constant rpm speed is different from my last exposure to dragsters.

Back in 93 when I was racing formula fords on the road course at IRP and Don Prudhomme was testing his traction control top fueler on the drag strip you could hear the engine rpm’s climbing.

 

[Jeff Wills]

meb <[email protected]> wrote in message news:<[email protected]>...
> When did drag racing switch to slip clutches?
>
> I suspect it has been since the early 90?s.
>
> This graph shows a relatively smooth acceleration, no 8G launch spike.
>
> The near constant rpm speed is different from my last exposure to dragsters.
>
> Back in 93 when I was racing formula fords on the road course at IRP and Don Prudhomme was testing
> his traction control top fueler on the drag strip you could hear the engine rpm?s climbing.

(This is wandering well off-topic, but what the heck- it's Christmas!)

I think multi-stage slipper clutches started appearing about 5 years ago, after the NHRA banned
electronic driver aids.

Jeff

 

[Carl Fogel]

[email protected] (Jeff Wills) wrote in message news:<[email protected]>...
> [email protected] wrote in message news:<d%[email protected]>...

[snip]

> . . . While Top Fuel cars use a single gear, they also have multi-stage slipper clutches. The
> clutch slips a set amount at the start, slips less at the middle of the run, and locks up
> completely at the end. This is all controlled by a mechanical-over-pneumatic timing system,
> electronic clutch management being prohibited by the NHRA.
>
> Multi-stage clutch tuning has risen to the same level as fuel injection tuning in the top levels
> of drag racing. IIRC, clutch technology is largely credited with lowering the 1/4 mile records
> from the 5.0 to the 4.4 second range.
>
> FWIW: I've been using a single-speed junker to get around town. In general I get through
> intersections quicker than most of the other commuters.

[snip]

> Jeff

Dear Jeff,

I do hope that your "single-speed junker," the one that you use "to get around town" and with which
you "get through intersections quicker than most of the other commuters," is a bicycle and not one
of your old dragsters.

I love this even-more-interesting-than-usual thread drift!

Thanks,

Carl Fogel

 

[Jeff Wills]

[email protected] (Carl Fogel) wrote in message news:<[email protected]>...
> Dear Jeff,
>
> I do hope that your "single-speed junker," the one that you use "to get around town" and with
> which you "get through intersections quicker than most of the other commuters," is a bicycle and
> not one of your old dragsters.
>
> I love this even-more-interesting-than-usual thread drift!
>
> Thanks,
>
> Carl Fogel

Yup, it's a rescued Raliegh- useful for the stoplight drags because it's got a relatively low gear
(44/17) for a single speed and light-but-strong wheels (36 spokes, MA-40 and Sun M14A rims). I built
it for the last three miles of my commute, after parking my Toyota where I don't have to pay
extortionate parking charges. Other days I ride all the way from home- but I usually only use 5 of
the available 24 gears on that bike.

And to drift things back towards on-topic, sort of: I help put on the Human Power Challenge in
Portland every year over Memorial Day weekend. We got drag races:
http://www.ohpv.org/pir2003/drags/index.htm .

(Sorry to burst your bubble, Jobst- but I'm an incorrigible weird bike nut.)

Jeff

 

[Tom Sherman]

Jeff Wills wrote:
>
> Yup, it's a rescued Raliegh- useful for the stoplight drags because it's got a relatively low gear
> (44/17) for a single speed and light-but-strong wheels (36 spokes, MA-40 and Sun M14A rims). I
> built it for the last three miles of my commute, after parking my Toyota where I don't have to pay
> extortionate parking charges. Other days I ride all the way from home- but I usually only use 5 of
> the available 24 gears on that bike....

But how many effective gear ratios does the bike have once duplicates and near duplicates are
eliminated? In a normal 3x8 setup, I would expect about 10 or so near duplicate ratios. I have a
stock bike with a triple crank and 8-speed cluster that has 10 ratios that are near duplicates
(difference of 2 gear inches or less).

Tom Sherman - 41 N, 90 W

 

[Carl Fogel]

[email protected] (Jeff Wills) wrote in message news:<[email protected]>...
> [email protected] (Carl Fogel) wrote in message
> news:<[email protected]>...
> > Dear Jeff,
> >
> > I do hope that your "single-speed junker," the one that you use "to get around town" and with
> > which you "get through intersections quicker than most of the other commuters," is a bicycle and
> > not one of your old dragsters.
> >
> > I love this even-more-interesting-than-usual thread drift!
> >
> > Thanks,
> >
> > Carl Fogel
>
> Yup, it's a rescued Raliegh- useful for the stoplight drags because it's got a relatively low gear
> (44/17) for a single speed and light-but-strong wheels (36 spokes, MA-40 and Sun M14A rims). I
> built it for the last three miles of my commute, after parking my Toyota where I don't have to pay
> extortionate parking charges. Other days I ride all the way from home- but I usually only use 5 of
> the available 24 gears on that bike.
>
> And to drift things back towards on-topic, sort of: I help put on the Human Power Challenge in
> Portland every year over Memorial Day weekend. We got drag races:
> http://www.ohpv.org/pir2003/drags/index.htm .
>
> (Sorry to burst your bubble, Jobst- but I'm an incorrigible weird bike nut.)
>
> Jeff

Dear Jeff,

Good Lord!

Those bicycle drag-racers are accelerating so fast that their upper bodies are being forced
visibly backward!

Carl Fogel