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Rans Rocket vs Rans Screamer in "time trial"



 
 
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  #1  
Old July 23rd 03, 02:13 AM
Brent Hugh
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Default Rans Rocket vs Rans Screamer in "time trial"

Just for our own amusement, my son (6 yrs. old) and I, riding our Rans
Screamer the other evening, did a 2.5 mile time trial on the circle
drive around the nearby sports stadiums.

The route is best described as "rolling hills"--low speed about 10MPH,
high speed about 28MPH.

We did it in 8:04 (18.6 MPH). (OK, neither of us is exactly Lance
Armstrong.)

So yesterday I decided if I ditched the kid & the 50 lb. bike I could
probably do better.

So I stripped all the excess junk off my Rans Rocket & rode the exact
same course.

Result? EXACTLY 8:04, again.

(Well, within 1 second, anyway.)

Coincidence, or what?

I guess the moral is that I can lug around an extra 75 lbs at all
times, and have it make no difference! (Well, the 6-yr-old DOES
pedal, so that makes up for at least some part of the extra 75 lbs . .
.. )

Or that the old saw is true--it's the engine, stupid.

The only spoiler is, that when I got home I found that my Rocket tires
were both at 60 lbs. Usually I keep them at 100 lbs, and that does
make a noticeable difference. The Screamer tires were at 95 lbs, just
where I usually keep them.

I guess I must go for try #3, to see if it's a tie-breaker.

--Brent
bhugh [at] mwsc.edu
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  #3  
Old July 29th 03, 11:08 PM
Brent Hugh
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Default Rans Rocket vs Rans Screamer in "time trial"

98GTW wrote in message news:
Brent, Your message caught my eye mostly because I'm curious how your six-
year-old manages to pedal the Screamer. My 8-y-o daughter doesn't fit at
all yet.
Have you modified the bike to fit (or does your son sleep in a special s-t-
r-e-t-c-h-i-n-g rack at night?)?


Naturally, it's the stretching rack . . .

Alternatively:

1. Seat moved all the way up until the bolt on the seat clamp hits a
frame brace & won't move up a millimeter more.

2. Self-inflating mattress (doubled over) + pillow behind him. We use
one of those buckwheat hull pillows so it's pretty stable. This moves
him forward quite a bit, though he still has more seat per square inch
of rear end than adults do . . .

3. Pedal reducers (cuts crank length about in half).

4. Pedal clip & strap to hold his feet in place.

He claims that he loves going on the tandem far better than going on
his upright trailerbike.

--Brent
bhugh [at] mwsc.edu
  #4  
Old July 29th 03, 11:28 PM
Brent Hugh
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Default Rans Rocket vs Rans Screamer in "time trial"

(Brent Hugh) wrote in message . com...
Just for our own amusement, my son (6 yrs. old) and I, riding our Rans
Screamer the other evening, did a 2.5 mile time trial on the circle
drive around the nearby sports stadiums.
We did it in 8:04 (18.6 MPH). (OK, neither of us is exactly Lance
Armstrong.)
So I stripped all the excess junk off my Rans Rocket & rode the exact
same course.

Result? EXACTLY 8:04, again.


So a couple of nights ago I figured if I tried it on the Rocket again,
pumping up the tires to 100 lbs, it would certainly make a difference.

Result? 8:06.

I did have one pannier on, with 5 or 6 lbs worth of stuff. Supposedly
a pannier increases aerodynamic drag by about 6%; see

http://damonrinard.com/aero/aerodynamics.htm

On a cheerier note, I continued and completed a 6-mile time trial
around the track. Time was 19:57 (just a hair over 18 MPH).

Last summer, almost exactly a year ago, on a similar machine (Trek
R200) I did the same route in 23:57 (a hair over 15 MPH).

Considering that my training routine is "go for a ride whenever you
feel like it and go as far as you want and as fast or as slow as you
want" that seems to me to be pretty decent progress for a year.

--Brent
  #6  
Old August 7th 03, 01:30 PM
98GTW
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Default Rans Rocket vs Rans Screamer in "time trial"

(Brent Hugh) wrote in
om:

98GTW wrote in message news:
Brent, Which crank reducers are you using? Do you know a source?


Look at

http://aebike.com/site/page.cfm?PageID=30&Category=133

This lists two "crank arm shorteners" made by Prism Design.

Also: http://www.ride2online.com/cintro.htm

These aren't the exact type I have, but the same basic idea.

--Brent
bhugh [at] mwsc.edu


Thanks, Brent. Now I've got to figure out if the shorteners will be enough.

--
Dave
98GTW

(remove nospam to reply directly)
Presto, Presto II, Screamer
  #7  
Old August 8th 03, 11:43 PM
Brent Hugh
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Default Rans Rocket vs Rans Screamer in "time trial"

(Brent Hugh) wrote in message . com...
Just for our own amusement, my son (6 yrs. old) and I, riding our Rans
Screamer the other evening, did a 2.5 mile time trial on the circle
drive around the nearby sports stadiums.


I know everyone here is just enthralled with the continuing saga of
the superhuman[1] speeds my 7-yr-old son & I have been achieving in
our series of time trials.

So here's the next installment.

Just for a little extra entertainment value, I've gone ahead and
solved the question that's been burning on everyone's mind: Is it
better to armor up your tires in order to avoid flats, or just ride
with normal tubes/tires and take the time to fix flats whenever they
happen?

Recently we've had a series of flats on the front tire of the
Screamer. I'm a belt AND suspenders kind of guy, so while I had the
tire off I replaced the tube with a thick, thorn-proof tube and ALSO
put a tire liner in.

When I got it all back together I couldn't help but observe that my
previously light-as-a feather wheel assembly now felt as though it
were filled with lead.

"I wonder what this new 45-lb front tire is going to do to our average
speed?" I mused, as three burly friends[2] and I lugged it over to
attach it to the front of the bike.

So, off to the track to find out. Results[3]:

2.5 mile course 6-mile course
---------------- ----------------
Rocket 7:55 (18.9mph) (not attempted)
(low tire press.)

Rocket 7:57 (18.9mph) 19:57 (18mph)
(with 1 pannier,
high tire press.)

Screamer 8:04 (18.6mph) (not attempted)
(original)

Screamer 8:15 (18.2mph) 20:35 (17.5mph)
(with thorn
proof tube &
tire liner)

On the Screamer, on both occasions, I was captain and my 7-yr-old son
Jonathan was stoker.

The Rocket had thornproof tubes and tire liners installed for both
time trials[4].


So here's the burning question you've all been asking yourselves:
Thornproof & tire liners on one wheel cost you about 2% in speed. Is
this worth it? That is, would you save time in the long run by going
2% slower all the time OR by running normal tubes/tires and stopping
to fix them when necessary.

If you can't stand to change tires (at night, in the rain, etc.) then
you already have your answer. But for the rest of us:

Assuming a flat tire every 200 miles, 14 MPH average speed, and 15
minutes to change the flat tire, we get 872 minutes to travel the 200
miles.

Assuming 2% lower speed because of thornproof tube plus tire liners,
we get 876 minutes to cover the same distance.

Assuming that replacing both front & back with liners & thornproof
tubes would cause 4% slower speed, we get 893 minutes to cover the
same distance.

So I guess if speed is your only consideration, ditch the thornproofs
& tire liners.

The combination really does work to stop flats, though. I had the
bike shop put this setup on my Trek R200 when it was new and now, with
something over 1000 miles on it, I haven't had a single flat yet.

The other day I dug a flat, razor-sharp piece of glass out of the
tire, about half the size of a dime. And I see three or four similar
gashes in the tires that must be from similar bits of glass. But no
flats.

Regular tubes & tire liners work pretty well, too. But eventually the
end of the tire liner wears through the tube--not good.

--Brent

[1] Oops--mis-spelled "subhuman". Oh, well . . .

[2] What with my wimpy bicyclist's arms and all, I need all the help I
can get . . .

[3] Those of you who took the trouble to memorize the previous results
I posted will realize that there is a slight discrepancy between those
and these. That's because I realized that I was using a slightly
different finishing line for the Screamer vs. the Rocket (the starting
line is well marked but the finishing line isn't). Lucky thing we're
not interested in submitting our world-record attempts to the IHPVA .
.. .

[4] It looks to me as though, with light tubes/tires and no pannier I
could break 20 MPH on the 2.5 mile time trial, and maybe the 6 mile
time trial, on the Rocket. I guess now I'll have to try it. I'm sure
Lance is trembling in his extremely expensive custom-made bicycling
shoes at the very thought . . .

--Brent
bhugh [at] mwsc.edu
 




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