Ergomo and Power Tap comparison

Some of you may know that the Ergomo bottom bracket-based power meter has
recently entered the market. Although some Ergomo dealers have done
private testing and comparisons of their systems, until now there has not
been any publicly-available data set that could be used for independent
evaluation. Last week, Ergomo-USA put some data files on their website
that were collected during a two-hour ride on a bike equipped with both
the Ergomo and the Power Tap Pro hub. I've had a chance to examine the
data and my comments are he
http://mywebpage.netscape.com/rechun...ergomo-pt.html

I have previously examined data from a ride where three different power
meters were installed: the SRM, the Power Tap, and the Polar S710 with
optional power module. That write-up can be found via the link at:
http://mywebpage.netscape.com/rechung/wattage

"Robert Chung" wrote in message
...
Some of you may know that the Ergomo bottom bracket-based power meter
has
recently entered the market. Although some Ergomo dealers have done
private testing and comparisons of their systems, until now there has
not
been any publicly-available data set that could be used for
independent
evaluation. Last week, Ergomo-USA put some data files on their website
that were collected during a two-hour ride on a bike equipped with
both
the Ergomo and the Power Tap Pro hub. I've had a chance to examine the
data and my comments are he
http://mywebpage.netscape.com/rechun...ergomo-pt.html

I have previously examined data from a ride where three different
power
meters were installed: the SRM, the Power Tap, and the Polar S710 with
optional power module. That write-up can be found via the link at:
http://mywebpage.netscape.com/rechung/wattage


Thanks for supplying the info Robert. Interesting to see another power
measuring device that probably doesn't perform any better than a
Powertap at almost twice the price. I would like to see the business
plan for this device. I like the longer sampling rate which will
eliminate the annoying frequent reading changes of the Powertap. The
higher reading is expected due to drivetrain losses although one would
expect to see this as a percentage and not a constant. Of course when
measuring only one leg the device can be deliberately fooled. I don't
see this as a flaw but don't pay too much attention to your readings
when doing one legged drills with either leg.

Phil Holman

In article t,
Phil Holman wrote:

Thanks for supplying the info Robert. Interesting to see another power
measuring device that probably doesn't perform any better than a
Powertap at almost twice the price.

Let's get the facts straight:

MSRP:
- PT w/Training Wheel - $799
- PT Pro w/Training Wheel - $999
- PT w/Race Wheel - $1099
- PT Pro w/Race Wheel - $1299
- Ergomo Sport - $1289

Now, I would also argue that if you go with a PT option, you need to pick
up a copy of CyclingPeaks Software as the PT software is pathetic! That's
another $75.

I think it's pretty hard to call that "almost twice". There are some other
significant advantages to the Ergomo, including:

o Use your own wheels.
o Rechargable battery.
o Lighter
o hardwired computer eliminates data drops

There are others, you can find details @ http://www.ergomo-usa.com.

Scott






--
-*- Scott Patton
-*- Colorado Springs, CO
-*- http://www.FixedGearFever.com
-*- Track Racing Web Services

"scott patton" wrote in message
...
In article t,
Phil Holman wrote:

Thanks for supplying the info Robert. Interesting to see another
power
measuring device that probably doesn't perform any better than a
Powertap at almost twice the price.

Let's get the facts straight:

MSRP:
- PT w/Training Wheel - $799
- PT Pro w/Training Wheel - $999
- PT w/Race Wheel - $1099
- PT Pro w/Race Wheel - $1299
- Ergomo Sport - $1289

Still as fiesty as ever Scott. The market demand for such devices being
able to support several companies is questionable. I thought the $300 I
paid for my PT was OK. It was used but the hub had just been replaced
and personally, I wouldn't pay over $1000 for one. This from their
website.....
"Fortunately for the consumer, there are several options on the market
to choose from. At $1279, the Ergomo Sport® is a great value considering
that the comparable competitor retails for more than twice the
price"........

They obviously don't consider the PT as being comparable.......more
straight facts no doubt.


Now, I would also argue that if you go with a PT option, you need to
pick
up a copy of CyclingPeaks Software as the PT software is pathetic!
That's
another $75.

I think it's pretty hard to call that "almost twice". There are some
other
significant advantages to the Ergomo, including:

o Use your own wheels.
o Rechargable battery.
o Lighter
o hardwired computer eliminates data drops

Using your own wheels is good and you could possibly use this on a track
bike if you can get the chainline right. There's a little extra hassle
when moving this to another bike unless you buy another BB sensor.

Phil Holman

"Phil Holman" wrote in message
k.net...

The
higher reading is expected due to drivetrain losses although one would
expect to see this as a percentage and not a constant.

While people frequently state that X% of power is lost in the drivetrain, in
fact this percentage declines with increasing power output - IOW, it appears
to be partially, if not largely, a constant. This makes sense when you
consider that 1) most of the friction in the chain reportedly arises as a
result of the links bending around one another, and is not due to rubbing of
the bushings on cogs or chainrings, and 2) on a geared bike, the chain bends
the most wrapping around the derailleur pulleys, i.e., on the lower run
where the tension is independent of power output.

Andy Coggan.

"Andy Coggan" wrote in message
k.net...
"Phil Holman" wrote in message
k.net...

The
higher reading is expected due to drivetrain losses although one
would
expect to see this as a percentage and not a constant.

While people frequently state that X% of power is lost in the
drivetrain, in
fact this percentage declines with increasing power output - IOW, it
appears
to be partially, if not largely, a constant. This makes sense when you
consider that 1) most of the friction in the chain reportedly arises
as a
result of the links bending around one another, and is not due to
rubbing of
the bushings on cogs or chainrings, and 2) on a geared bike, the chain
bends
the most wrapping around the derailleur pulleys, i.e., on the lower
run
where the tension is independent of power output.

Good point. One would therefore expect to see a difference in Ergomo
readings between very high and very low cadences for a given power on a
PT reading.

Phil Holman

"Robert Chung" wrote in message
...
Some of you may know that the Ergomo bottom bracket-based power meter has
recently entered the market. Although some Ergomo dealers have done
private testing and comparisons of their systems, until now there has not
been any publicly-available data set that could be used for independent
evaluation. Last week, Ergomo-USA put some data files on their website
that were collected during a two-hour ride on a bike equipped with both
the Ergomo and the Power Tap Pro hub. I've had a chance to examine the
data and my comments are he
http://mywebpage.netscape.com/rechun...ergomo-pt.html

I have previously examined data from a ride where three different power
meters were installed: the SRM, the Power Tap, and the Polar S710 with
optional power module. That write-up can be found via the link at:
http://mywebpage.netscape.com/rechung/wattage

Until I found out it only measures one side, I thought this was potentially
the best system. You can use virtually all of your own equipment, and other
great features. Measuring one leg could be a deal breaker for me, especially
if the athlete has no way to determine what his or her power distribution
is. I have seen many athletes that have more slow twitch pwer on the non
dominant leg and of course more fast twitch on the dominant side.

What a let down. I guess it still serves a lot of purpose, it is just not as
ideal as I had thought.

How is the softwares? What is the raw data format?

Thanks Robert

"scott patton" wrote
There are others, you can find details @ http://www.ergomo-usa.com.

Thanks for the link Scott. Just looking at the device, it seems to me that
it can only measure torque carried by the bottom bracket spindle which means
it can only measure left leg power/torque.

If you are just using it to follow your own training it might not matter.
Then again, you might adopt a left pedal power style to get bigger numbers
;-) Can't imagine paying that much for a device with such a large inherent
assumption.

Cheers,

Jim


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Phil Holman wrote:
One would therefore expect to see a difference in Ergomo
readings between very high and very low cadences for a given power on a
PT reading.

This is why I was trying to identify the gear ratios used, and why my
comments may seem overly obsessed with cadence -- I need to use speed and
cadence to figure out exactly when the switch is made from one gear ratio
to another. I was trying to figure out whether there was a difference in
recorded power based on the chainwheel-cog combination being used. An
annoying side issue in my analysis was that the two wheel circumferences
weren't set exactly the same, and I needed to fiddle with them to figure
out which circumference may have been closer (since the cadence was so
flaky, I need pretty good info on speed in order to differentiate between
similar numeric gear ratios that come from a small chainring-small cog
combo vs. a large chainring-medium cog combo).

As to whether the Ergomo is worth the money, I have no opinion. I've never
used either of these two devices. This wasn't a comparison of features or
usability, which other people have done. I was simply looking at the
quality of the power data, which others haven't. I think the evidence from
a sample size of 1 is that consistency of power measurement doesn't appear
to be an issue to worry about, and you should decide based on features and
usability and reliability (and price).

"Nick Burns" wrote in message
m...

How is the softwares? What is the raw data format?

The Ergomo comes with a customized version of the best powermeter software
on the market: www.cyclingpeakssoftware.com. That means the data are saved
in .wko format, but of course can be exported in any form your heart desires
(.csv for PowerTap, .txt for SRM, .??? for Polar, etc.).

Andy Coggan