Bicycle Computers - what do they do?

In article <[email hidden]>,

Michael J. Klein said:

On Fri, 25 Jun 2004 23:08:21 -0700, Ryan Cousineau <[email hidden]>

Quoted message said:

In article <[email hidden]>,

<snip>

Quoted message said:

Cateye makes the CC-HB100 heart rate cyclecomputer. I have one, and
would be really happy with it if it had 2-bike wheel memory and recorded
Max heartrates.

It's quite common to have a bike computer and then a separate heart rate
monitor, but I believe some Polaris bike-specific models integrate some
fairly funky features (the CC-HB100 integrates a fairly bogus "calorie
counter" based on heart rate and speed, but it doesn't even have an
entry for rider mass, so I would suggest it is only useful as a relative
effort measurement).

Hmmm... gives me some new product ideas. I'll be talking with some
suppliers on Monday.

Well, as long as you're taking requests, here's my dream computer:

-Heartrate, cadence, and oh, how about an Avocet-style altimeter?
-Heart rate computer should remember peak and average HR; the Cateye
also has programmable range indicators, in which it puts up a little
arrow if your HR is above or below the numbers you put in.
-Average and peak cadence memory, too.
-use the altimeter and speedometer to generate instant VAM (see Dr.
Ferrari) numbers!
-allow user to enter their weight. Use that to generate a
not-entirely-bogus calorie-meter, but also to...generate moderately
accurate power output numbers, at least on hills!
-must be able to handle two wheel sizes. Three would be even nicer, but
not necessary. A corollary is that making extra wiring harnesses
available for a nominal cost is a nice advantage. Cateye does this,
though the last time I checked I ended up buying a computer, because it
cost $5 more for the cheap computer than for the separate harness.

-Downloadable-to-PC data is cool, but probably adds too much cost.
-I have little interest in wireless units (except, for obvious reasons,
the heart rate transmitter) because I am allergic to buying batteries.
But it's probably a market advantage.

Note that the competition in the low-end computer market has taken a
turn for the weird. Filzer now makes a competent non-cadence computer
for a price that, at wholesale, must be remarkably close to nothing:

http://filzer.com/catalog.html

The MEC listings:

http://tinyurl.com/22l4q

The full-featured dB4L is C$14.50. There's a dB2L for $12.50, but I
don't think that's enough price difference to sway anyone. It's possible
the cheap computer only exists to make the 4L look like an even better
deal.

And then there's the dB4W, the wireless version of the 4L. it's C$24.00.
That's less than USD$18. For a wireless computer.

Now for the bad news: Filzer has started making HRMs now, too.
Performance doesn't sell them under the Filzer name, but the high-end
one costs $50:

http://www.performancebike.com/shop/large_photo.cfm?SKU=17163&Store=Bike

Share & Enjoy,
--
Ryan Cousineau, [email hidden] http://www.sfu.ca/~rcousine/wiredcola/
President, Fabrizio Mazzoleni Fan Club

In article <[email hidden]>, Michael J. Klein

Quoted message said:

Tom, if the display gets much smaller, it'll be mounted on a display
console which protrudes from my chest so I can see the darn thing up
close!

Get a Cateye Mitee 3

Tom Gibb <[email hidden]>

Captain's log. On StarDate Sat, 26 Jun 2004 09:36:06 +0800 received comm from
Michael J. Klein <[email hidden]> on channel rec.bicycles.tech:

: I use a GPS on my bike. I've read some info about bike computers, and
: it seems like they don't do anything that my GPS does. Is that a
: correct assessment? Also, I would like to know more about bike

No.

I don't think your GPS will do for example:

Cadence
Heart Rate
Power

: computers and I will read any suggested information.

http://www.polarusa.com/Products/Consumer/S720.asp

Best regards,

martin törnsten

--
http://82.182.73.126/

Michael J. Klein said:

I use a GPS on my bike. I've read some info about bike computers, and
it seems like they don't do anything that my GPS does. Is that a
correct assessment? Also, I would like to know more about bike
computers and I will read any suggested information.

In their simplest common form, they count the wheel rotations and
their durations, and calculate and display the information that can be
derived from that raw data; current speed, distance traveled, average
speed, etc. More sophisticated units also sense, calculate and
display gear ratio and pedalling cadence. There are also units which
engage in biomonitoring of the rider, but I place those in a different
category since they are monitoring more than just the bicycle.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Surrealism is a pectinated ranzel.

Michael J. Klein said:

I use a GPS on my bike. I've read some info about bike computers, and
it seems like they don't do anything that my GPS does.

A GPS tends to give an approximation of distance travelled based on
apparent movement within the mapped space. The inability of the
instrument to detect minor changes in position makes this a less
accurate method of measurement of motion for a bicycle than the more
direct method used by the on-board physically linked computer, which
gives a calculation based on measured wheel motion. A wiggly path can
make a short direct-line distance into a much longer actual trip.

--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Surrealism is a pectinated ranzel.

Werehatrack said:

A GPS tends to give an approximation of distance travelled based on
apparent movement within the mapped space. The inability of the
instrument to detect minor changes in position makes this a less
accurate method of measurement of motion for a bicycle than the more
direct method used by the on-board physically linked computer, which
gives a calculation based on measured wheel motion. A wiggly path can
make a short direct-line distance into a much longer actual trip.

I have three speedometers on my motorcycle, stock Suzuki, Garmin GPS
III and Sigma BC400. I believe the GPS is _very_ accurate on long,
straight level runs. Assuming you agree with that, the Suzuki's spedo
is ~ 7.5% off (reads consitantly high) and the Sigma is about .6% off,
also, also consistantly high. Note that the BC 400 is the lowest end
Sigma, and only allows 3 digit wheel diam resolution; I have faith
that the BC 1400 (4 digit)on my LiteSpeed is more accurate yet.

"Mike Lackey" <[email hidden]> wrote in message news:<lFhDc.158449$3x.28959@attbi_s54>...

Quoted message said:

Iffn' you ask me... bicycle computers are like crack. It's amazing how
easy it is to become addicted to average speed (wow, 17.6 mph with all those
climbs), or elapsed time (hey, did my last century in 5 hrs 50 mins with
stops). One or two rides and you find yourself selling your soul for faster
elapsed times, never satisfied, always looking to score.

I find that my most enjoyable rides are the ones where I've forgotten to put
the dam thing on the bike and just ridden my own pace.

My advice... just say no.

Mike Lackey
Madison, AL

Well, I have a GPS and a cyclometer on the bars. I have to say that I
enjoy riding more with them than without. Last year I was a little
measurement crazy (checking HR, blood pressure, weight every morning,
logging every ride in a huge spreadsheet, etc). This year I've found
that those logs are about worthless, my HR and BP are very stable
(they were last year, too, which ironically caused them to increase).

However, I do like looking down and seeing how far to the next turn
without having to think about it, a quick glance to see altitude, and
being able to keep an eye on my HR and cadence makes it possible to
ride much further.

Eric

KD said:

Werehatrack said:

A GPS tends to give an approximation of distance travelled based on
apparent movement within the mapped space. The inability of the
instrument to detect minor changes in position makes this a less
accurate method of measurement of motion for a bicycle than the more
direct method used by the on-board physically linked computer, which
gives a calculation based on measured wheel motion. A wiggly path can
make a short direct-line distance into a much longer actual trip.

I have three speedometers on my motorcycle, stock Suzuki, Garmin GPS
III and Sigma BC400. I believe the GPS is _very_ accurate on long,
straight level runs. Assuming you agree with that, the Suzuki's spedo
is ~ 7.5% off (reads consitantly high) and the Sigma is about .6% off,
also, also consistantly high. Note that the BC 400 is the lowest end
Sigma, and only allows 3 digit wheel diam resolution; I have faith
that the BC 1400 (4 digit)on my LiteSpeed is more accurate yet.

A 700C wheel is about 2.2 metres diameter; even a 17" wheel is over a
metre in diameter IIRC, so 3 digits (220cm v. 100cm) should be accurate to
better than 1 to 0.5%.

On uk.rec.cycling there was a recent argument about whether the path
followed by the front wheel was longer than the path followed by the rear
wheel. Could that be an issue?

Are there any applications (training, time trials...) where such accuracy
is necessary?

I use my computer mostly to remind me when to change the chain 🙂 OK, I
enjoy seeing how fast I'm going: I just don't look whilst I'm moving
slowly.

AC

anonymous coward said:

A 700C wheel is about 2.2 metres diameter; even a 17" wheel is over a
metre in diameter IIRC, so 3 digits (220cm v. 100cm) should be accurate to
better than 1 to 0.5%.

I think you meant to use the word circumference rather than diameter.
Diameter equals radius * 2. Pi * diameter = circumference. The
diameter of a 700c wheel is 0.622 meters without a tire. To get 2.2
meters for circumference, you're going to need a pretty wide tire;
roughly 700x38 I would guess.

Bill Davidson said:

anonymous coward said:

A 700C wheel is about 2.2 metres diameter; even a 17" wheel is over a
metre in diameter IIRC, so 3 digits (220cm v. 100cm) should be accurate to
better than 1 to 0.5%.

I think you meant to use the word circumference rather than diameter.

I stand corrected. Back to primary school for me...

Quoted message said:

Diameter equals radius * 2. Pi * diameter = circumference. The
diameter of a 700c wheel is 0.622 meters without a tire. To get 2.2
meters for circumference, you're going to need a pretty wide tire;
roughly 700x38 I would guess.

Bill Davidson said:

...The diameter of a 700c wheel is 0.622 meters without a tire....

The diameter of the bead seat is 622-mm. The outside diameter of the rim
will be slightly larger.

--
Tom Sherman – Quad City Area