SRM or Ergomo

A light bike doesn't replace good fitness.

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JTC
Posts: 571
Joined: Wed Oct 22, 2003 6:05 pm

by JTC

I was looking through the recent posts on power meters and have to decided to purchase one. Right now I am stuck between the SRM Pro (accuracy of +/- 2%) or the Ergomo (also +/- 2%). I know there are a few folkes with each one. What are the pros and cons of both? At about $1500 more its hard to justify the SRM, and they both seem to work by a similiar method. Are people happy with the Ergomo?

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spaniardclimber
Posts: 1159
Joined: Fri Dec 05, 2003 10:15 am

by spaniardclimber

I've been using the ergomo since february and Im very satisfied with it, it should improve some features such as being able to view the avg power during an interval,and the screen could be much smaller too, but in avg Im very pleased.
I chose ergomo because of price and because I could use it in an indoor trainer and with any wheelset. If you have any questions feel free to ask.

by Weenie


Geoff
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Joined: Sat Dec 13, 2003 2:25 am
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by Geoff

As my coach is fond of saying, it really doesn't mater which you choose so long as you have one! It will make a difference to your performance.

I have been using the SRM for 3 or 4 years now and strongly recommend it. My coach (who has a degree in exercise physiology, as well) did an interesting test with a combination of SRM, Powertap and Ergomo all on the same bike.

The biggest problem with the Powertap and the Ergomo are related to functionality (Powertap does not allow wheel changes, Ergomo does not as easily allow bike changes, eg. Road, TT etc.). The following were the general conclusions:

"What's the cheapest option? PowerTap or Polar (not tested here). Then Ergomo, then SRM. What's the most expensive? SRM Professional. What's the lightest? You're not buying a powermeter for lightness, so who cares? There's better places to save weight than your powermeter. Once you understand power output, you'll realize how insignificant one or two hundred grams is if you have poor power pacing. What's the most functional? SRM, undoubtedly. Averages, maximums, intervals, training zones, time and temperature - and all on the handlebar computer. The software isn't fancy, but very powerful. PowerTap has configurable displays, but a lack of analysis features on-bike - does anyone use the software anymore? Cyclingpeaks Software narrows the software gap by offering compatibility with all Power meters. Ergomo has quirky displays, and no interval functions, but basic and easy. With Ergomo (in USA), Cyclingpeaks Software is standard."

If you are interested, e-mail me and I will put you in-touch with my coach.

Francois_Viviers
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Joined: Sat Oct 25, 2003 7:12 pm

by Francois_Viviers

There will always come a time when you would want to compare your power output to someone elses.

This is impossible with systems like Polar and Ergomo.

There will be small discrepensies between powertap and SRM this is due to power loss through the chain and drivetrain fiction. This would be about 1.5% - 2%

Not much and on smaller numbers the difference would not be that important.

The problem with Polar is that reading can be way off due to complicated installation and also the fact the the system is quoted to be up to 10% at times. With this system you might even have problem with repeatability, due to chain wear and dirt.

The Ergomo is better on repeatability and changes to pedaling style would be gradual. But if you have a left right leg power discrepency and correct that overnight, power reading might be way of. Depnding on size of discrepency.

Both Ergomo and Polar would be difficult to compare to more the other 2 system, simply because of the way they measure power. Therefore SRM and Powertap are probably more accurate in a large scale popluation test tha the other 2 systems

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spaniardclimber
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by spaniardclimber

I don't agree with you, ergomo only has erroneous readings with a very big leg imbalance, as an example here is a 2h comparison with powertap.

http://mywebpage.netscape.com/rechung/w ... mo-pt.html

If you only ride one bike with multiple wheels, ergomo is the way to go.
Regards,
Gonzalo

Francois_Viviers
Posts: 175
Joined: Sat Oct 25, 2003 7:12 pm

by Francois_Viviers

I have 3% discrepency because of old injury, a lot of people have discrepencies because of leg lenght variants, cycling motion etc....

My 3% would be doubled, so I would have 6% - 1.5% = 4.5% overestimation.

There is also the fact that subconsiously you might start generating more power with your left leg when doing tests.

As I said it would not be that accurate if taken in a side by side test with a large test group.

But for some individuals it would be good.

The fact still remains that it cannot be argued that this system is as accurate as SRM or Powertap with a group of riders testing, in the same conditions

Paul_nl
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Joined: Sat Nov 15, 2003 4:35 pm
Location: The Netherlands
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by Paul_nl

Why does the ergomo have problems with power measuring when there is left right leg power discrepency?

Power = power? Right? Why should a legt right leg power discrepeny have influences on the powermeasuring?



Is it possible then to use the ergomo when you are cycling perfect round circles with the powercranks (http://www.powercranks.com). I want an powermeter on my trainingsbike and on that bike I use sometimes a normal crank and sometimes a powercrank.

Francois_Viviers
Posts: 175
Joined: Sat Oct 25, 2003 7:12 pm

by Francois_Viviers

The Ergomo measures power by deflection in the BB axle. There will not be sufficient flex when applying power with the right leg as power runs through the drivechain. On the left the power runs through the axle to the right. This description might not have the 100% technically correct wording.

So Ergomo measures deflection from power on left leg and doubles this. Thus if there is a big discrepency it would be out. It would be possible to meaure left right balance with a computrainer or SRM. If this shows that power balance is good then Ergomo would be pretty acurate.

Then you could also just not care, and just trust the thing. But that is not enough for some :?

by Weenie


Paul_nl
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by Paul_nl

Francois_Viviers wrote:The Ergomo measures power by deflection in the BB axle. There will not be sufficient flex when applying power with the right leg as power runs through the drivechain. On the left the power runs through the axle to the right. This description might not have the 100% technically correct wording.

So Ergomo measures deflection from power on left leg and doubles this. Thus if there is a big discrepency it would be out. It would be possible to meaure left right balance with a computrainer or SRM. If this shows that power balance is good then Ergomo would be pretty acurate.

Then you could also just not care, and just trust the thing. But that is not enough for some :?


Thank you.

An ergomo for my powercrank bike and a SRM for my other bike :oops: :lol:

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