I'm also in the market for a power meter, but I'd like to know more about the different options and accuracy of different models.

I know some WW use power meters and there is heaps of info on the web on how to use them, but I can't find a good review of the different models.

Some give a less acurate reading based on chain speed and gearing, which is ok for training to monitor power improvements, but I'm looking for one that gives me accurate readings based on power, so I can do technique training with data on max power output.

How do the different models work?

This http://midweekclub.ca/powerFAQ.htm and

this http://www.biketechreview.com/archive/pm_review.htm

should help.

One final thought is your ride. Integrated BB will affect your decision, along with your wheelset if you have multiple.

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John979

I think it will depend on how much you want to spend.

for price took out the SRM as an option. one of my team mates uses this and claims it to be the best there is. he has owned polar, powertap and now the SRM.

Which leaves me with the powertap, ergomo, and polar. I've tried the polar. It's a pain to use and not very accurate. constantly adjusting. just lots of problems. two others on my team had the same experience. right now i'm waiting for the powertap pro. I was waiting for the powertap SL but production on it has been halted. i've been waiting since last November. i've heard that powertap has it's own problems. some of my teammates are having battery life issues.

there was a recent issue of bicycling that review the four options listed.

If you want to have different wheel options, and one bike, go for ergomo. If you want to be able to use different bikes and one wheel go for powertap.
If you want to be able to use different bikes and different wheels go for SRM, allthough for the price of 1 SRM you could buy 2 ergomo sensors for 2 bikes

There is a new and improved version of ergomo (ergomo Pro) comming out in the next few months.

Another important thing is that you buy the device that has good customer service in your country, as sooner or later you'll have to send it for repair/maintenance etc.

How does the SRM allow you to use it on completly different bikes?

Different rear wheel sounds acceptable (I'd like some of my juniors to be able to use it).

You just have to switch cranks. For what I've read of SRM users it's an easy task. You can even change only the right crank.

My problem has always been that I have an integrated bottom bracket, which has historically limited m choices to Polar and PowerTap. However, Cannondale is now offering bicycles with an SRM SI option, and rumor is the will be offering an SRM upgrade option to existing SI owners. I may then get an SRM.

Regarding PowerTap, while lauded in many circles, its not without its difficulties. There have been major problems with the PowerTap SL, and the other models have quality problems. It seem like if you get a good one you will be OK, but if not expect a series of factory returns. I have been luck with mine so far. Plus, the wiring and setup is not as easy as one would expect, as hub receiver placement can be finicky. Finally, if HR data is vital, PowerTap has much more interference than any other HRM I have owned.

Current Ergmo also has reliability problems and it measures power for one leg only and doubles it, which some find suspect. It also has reliability problems.

Finally, I was lucky to get my first Polar as a gift. My mother is a high school administrator and got one on a steep discount, so I got a very nice Christmas present in 2003. This Polar unit was problematic. I returned it, and have had no problems with since, nor with the second sensor I purchased for my TT bike. Setup is more time consuming and one must be careful with the chain speed sensor because if its improperly wired, a chain drop will snap the wire. This happened to me and I subsequently installed a Deda dog fang to be safe.

Of course the real issue regarding the Polar is data quality. Again, when properly setup, the Polar is surprisingly accurate. I have not done any comprehensive tests, but I will soon and will report. The main problem with Polar is capturing fast peaks, as Polar uses a 5 second recording interval. Therefore, the Polar is more suitable for long interval training and TT pacing, where when properly setup it is better than 5% accurate, and more important its highly repeatable.

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John979

Is there more to installing the Powertap than changing the rear wheel?

HR isn't a major issue as I know my HR very well (I heard some PM can read the HR of your competitor and I can see how this could be useful).

Powertap seems to be a good comprimise.

Powertap is an easy change, provided both bikes are setup with the wiring harness. But, if you have a set of aero wheels and want to have a race/training combination, you need two hubs, which can get pricey...

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John979

How much does the wiring harness cost?

I'd only be using it for training and races I consider training.

Was thinking of building onto a AC 420 rim (strong enough for everyday use, light and aero for mild competition)

Bruiser;

I can't remember the exact cost for the harness but I think its around $75 US. I would consider racing with it as well as it will provide invaluable data.

Another great feature about Power Meters is that they become a motivational tool. You do your workout, then rush home to see the results!

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John979

Bruiser, do you already know which powermeter it is going to be?

I asked at slowtwitched about the new ergomo pro. The information I got there was that only the computer has changed (better interval options).

Probably a Powertap. Havn't decided between the standard or pro.

I have Polar now in my TT-bike. Works well and it'seasy to assemble IF you know how to do it. Polar Powermeter manual sucks hard in THAT section!

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Samu @ www.signature.fi

I found my polar power kit pretty easy to set-up. being a ww, mean't I didn't need to take my chain off to weigh it...

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"Ride it like you've just stolen it!"