Just curious. PM seem the way to go but they maybe expensive and since they are so new, are they reliable and accurate?

I've read about the one that Landis used, I think it's the Cycle Ops. Any others out there?

iBike
Polar
Powertap
Ergomo
SRM

maybe soon Minoura, but that's only based on web site info.

I'd say the best power meter for the money is the Powertap, but that's only because I own one and that's what I want to tell myself. I wouldn't consider the Polar or the iBike.

iBike, worthless
polar < powertap < srm in terms of accuracy

No idea about the ergomo.

funny this came up. i'm researching power meters for a new bike i'm planning to buy. i'm leaning towards the ergomo right now. $1600 or so, from what i'm seeing. supposedly it's quite accurate. it mounts in the BB, so it's supposed to be really protected from the elements. advantages - you can swap from training to racing wheels and still have it providing power on your bike, it can handle multiple files (unlike the stupid powercrap), it's only 100 grams heavier than a dura-ace BB, and the battery is rechargeable. i'm leary of it because it doesn't use strain gauges; it's an optical read of the torque in the BB, so all it can sense is the power generated by your left leg. it simply assumes the right is putting out the same kind of numbers. this is fine if you have a pretty even power output throughout your cadence. it's gonna be off if one leg is stronger than the other. that said, i've read where having a 5% difference in leg strength means less than a 10 watt difference in power output, so maybe it's not a big deal. since it stays on the bike and allows you to put any and all wheels on it, and it's half the cost of the SRM, i'm thinking hard about giving the ergomo a shot. check with vino. he has one

-smoke

SRM is the best if you can swing it.

If you are racing, I would vote SRM since it does not limit your wheel choices. Next I would say Powertap. Though You could have two powertaps, one on a training wheelset, and one on a deep carbon set, but no go on a disc wheel. It would work itself to about the same price. Next I would say ergomo, but i've heard that they still have bugs to work out.

And is quite happy with it. I've also got an SRM, and have several friends with Powertaps; I'd like to think I'm pretty objective.

Like all powermeters, installation and calibration make the difference. The newest Ergomo seems to have the bugs worked out of it, I had a couple of early issues that were as much user as machine. Since then I've put around 2500 miles on it and am pretty happy, it's easy to calibrate, consistent, and has been dead reliable. Much happier with it overall than the SRM for ease of use, readability, and functionality.

So I did some intervals the other day and was a little surprised at the number being as high as it was. Took the climb and time data over to a couple of the online calculators, it was within 3 watts (last year I did the same with the SRM and it was within two on a 40k TT). So that's two pieces of good news

Sigh.

Actually, in terms of accuracy it's:

Powertap= 1.5%
Ergomo=2.0%
SRM=2.5% for Pro and 5% for Amateur.

So, to answer the question, it appears that the Powertap is the best PM for the money.

Its manufacturer's claimed accuracy. But honestly, as long as the power readings are consistent,accuracy doesn't matter too much.

Oh, I know, but when it comes to PM's, people just quote what they hear. Right now SRM's are the hot PM, so everyone raves about how much better they are. Some hear that Polar is unuseable junk, so that's what they repeat instead of being objective and researching.

"polar < powertap < srm in terms of accuracy"

Was the quote, so I refuted it. And yes, like I say in my other posts, as long as it's repeatable day after day, it's a decent powermeter. Except for that damn Ibike.

floyd landis used the power tap SLX (not currently released), it's a wireless version of the powertap SL. I like power tap, yes it does claim to be a little more precise, and measuring at the hub instead of the BB does make more sense to me since it's closer to where the power is relayed to the ground thus eliminating sources of error like the drive train. I like my power tap cause i can switch my wheel between bikes in under 5 minutes, i sure i had to buy another 50$ wirring harness for the second bike, but the big thing is that with that 50$ extra harness i'm able to move my yellow powertap computer, and powertap wheel to any bike i want very quickly. So if it's rainning or snowing out and i want to ride my beater bike, instead of my nice carbon bike i can swap wheels on the two bikes and i'm ready to go. SRM does have the freedom of using anywheels isntead of wheels with a powertap hub, but powertap wheels are growing in selection. I don't see the logic of comparing the price of an SRM alone (over 2000$) to a powertap sl (1000$ with set of basic mavic wheels), even if you buy another another set of carbon wheels w/powertap for 2000$, you're at 3000$ and you have 2 wheel sets. 3000$ most likely will not get your an SRM a basic set of wheels, and a set of carbon racing wheels. So to me powertap is cheaper.

Additionaly there is the problem that cycleops has yet to put out a disc wheel powertap option, well, you could always purchase a set of zipp 808's or 606's. The rear (85mm?) deep profile is supposed to be as close to a disk as you can get these days, but it offere's of the advantage of being race legal in all road event's, not just TT's. Just something to consider.

I would give serious consideration to a Ergomo Pro. I just picked one up, and the feature set is pretty good for its money. The accuracy is also good, as others have said, and it picks up your power at the BB, allowing you to use multiple sets of wheels.

The onboard computer also has info like TSS, NP, AP, all instantly available. I personally like the altimeter feature.

Also, because they're less well-known than the other alternatives, they can be had for well below retail on eBay. I've seen a couple used ones go for below $1000, and I got mine new for just a little above that.

SRM is also very nice, but it's a lot of computer for a lot of money. If money were no object, I would go that route. But for $2000 less, you can get an Ergomo Pro, or even less, a PowerTap, and have some very useful power data.

The wireless PowerTap 2.4 has been ot for a while now.

And the SRM measures closer to where the power is produced giving a more direct measure of what the rider is doing. Take your pick.

First, there's always the option of a wheel cover to convert any wheel into a disk with equal performance at a slight weight penalty. Second, in the U.S., disk wheels and wheel covers are legal in all races except those run under USCF equipment regulations (currently international selection races, record attempts, and possibly National Championships).

Buy Coggan and Allen's book. You'l want it if you buy a power meter anyway,and it goes over the different power meters.

IMHO: 1)SRM if you can afford it;

2) Ergomo or Powertap SL or 2.4.
The ergomo has the advantage of using mulitple wheels. PT the advantage of multiple bikes.

3) powertap pro.

Below that (Polar or Ibike) I wouldn't bother.

Powertap should have a disc option out in the next year, so I'm told.

Is there any wattage variance from using a heavier rear wheel(ie. train heavy race light, PT for training and a carbon tubbie for racing). If so, then the SRM or the ergomo would be a better/more consistent unit of measure as the value is taken from the same place every time.

OK, the OP asked best for the $$.

Is the Polar utterly useless crap? At 1/3 to 1/4 the cost, from what I've seen it is ~10% accurate compared to 1-3%. If the error is relative (i.e. always off but repeatably), how can that NOT be the best cost/performance option? Is the exact wattage key, or fairly accurate, though not exact, power trends?

Because you need to buy the Meter itself, which if you're lucky is 150-200 used. Then you have to buy a compatible Polar watch for 250-400. Add that up and you could get a nice Powertap that isn't a pain to set up.

The problem with the cheaper power meters is that their accuracy is very inconsistent. Under certain conditions, they can be very accurate. In other conditions, accuracy is known to be pretty weak. How valuable these things are overall depends a lot on the type of training you are doing.

10% isn't close enough to be worth training by. YOu might as well use just an HRM

Again, if you have the watch and have $100, the Polar is not bad at all. Sure, in the big/big, it may read off, but throughout the range, it is pretty consistent. Consistent enough that someone who is thinking about getting into power could ride with it for a season and see if they will stick with it, as I did.

Now, is it a dead accurate measure? Sometimes. But it's definitely better than HR alone.

How so? If my routine is all off by the same relative error (say 10%), then I may be at 225W instead of 250W by the meter. If I dial it up to 400W by the meter, but really am at 360W, then I really am 15W off (I thought I went up 150W but really went up 135W). Is 15W that big a deal?

If the error is absolute (real W + 15W for example) then I don't see it as an issue at all.

Not trying to argue, but to understand.

If the error is off consistently and repeatably, the manufacturers would surely account for that in their calibration, no?

The error figures are there for a reason, because they are inaccurate to varying levels. 10% doesn't necessarily mean 10% lower all the time, or even most of the time. It probably means that the size of error depends on a bunch of factors and riding conditions

Say, for example, your goal is to be able to produce 300W at LT for the upcoming season - when your powermeter says 300, you might be anywhere from 270-330W, a 60 watt difference. I'd say 10%, in any case, is quite a lot.

I don't know if your 10% number is accurate, but the error numbers that they talk about are averages. The device might be 50% high some times and 50% low some times. When you average all the errors together over a long ride, the total error might be plus or minus 10% (maybe +10% today and -10% tomorrow). These kind of errors might be useful enough for some kinds of training, but not for others.