Power Meter?

Triathlon Forum
1

I’m talking to my LBS about a power meter. Recommendation is the HAC 4.

Any comments from the list about this product??

Shoud I buy the HAC 4 PLUS - that allows me to down load data to my computer (does it work with MAC I-book)?

2

What are your goals?

What do you hope to accomplish with it?

This is not a power meter. It simply automates what you can do yourself more accurately with analyticalcycling.com and a topo map, ie, the power measurement functions only work correctly on uphill stretches IIRC.

http://www.midweekclub.com/powerFAQ.htm

3

HAC 4? What is that? I think the only real options are the SRM, Power Tap and Ergomo. You want a strain guage based unit for sure.

I have 4 Power Taps (don’t ask) and I love them all, they are simple, easy to calibrate and work flawlessly.

Kurt

4

Someone had a good comment the other day about power meters vs. power guesstimators. The HAC4 falls into the latter category. A riding buddy of mine has one and the thing is a really nice cycle computer but not a power meter.

5

I have 4 Power Taps (don’t ask)
Kurt

Sorry, I’ve gotta…FOUR???

Cam

6

I have three powertap wheels, and four powertap cpus.

7

2 700c road training wheels. 1 PT SL built into a 404 tubular (race wheel), and 1 built into a MTB rim. MTB might be unnecessary as the power is so variable that it is really hard to decipher. But I am addicted the data collection so I use it.

Kurt

8

I’ve heard this argument before, that MTB data is too variable to be of use, and that may be the case for pacing, but not for training and/or race analysis.

Regarding the OP, don’t waste your money on an HAC, find a cheap power tap and at least use that for training.

9

Did you say you wanted a powermeter or did you say you wanted a computer that can have power? If you said the former and they came up with a HAC 4, I doubt that they are really serious. In the HAC4’s database are the settings you provide on your height, weight, max heart rate, vo2 max etc. Not sure of the formula but the HAC4 compares your exertion (functions of your heart rate and cadence and forward speed) against an ideal curve. So for a rider of given mass, height, v02max etc at given heartrate and cadence and speed he should be producing a given power output. HAC4 watts = virtual wattage found in X% of real riding situations which is virtually worthless, not particularly accurate and not repeatable.

For true power (without pitot tubes and inclinometers and a whole bunch of user inputted parameters) you need a mechanical measure of torque and rotational speed. This means strain gauges and magnets. Or you can use derived measures like polar by measuring chain vibration + cadence, to approximate chain tension, and thus calculate power based on chain tension and chain speed.

Read this: http://www.midweekclub.com/powerFAQ.htm#Q5

10

I’m talking to my LBS about a power meter. Recommendation is the HAC 4.

Any comments from the list about this product??

Shoud I buy the HAC 4 PLUS - that allows me to down load data to my computer (does it work with MAC I-book)?

Oh my God! Grab your wallet and get the hell out of that bike shop. That thing is not a powermeter.