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HAC-4 Class 101(7 posts)

HAC-4 Class 101Juanmoretime
Jan 10, 2004 10:41 AM
Having bought myself a new toy, a Ciclosport HAC-4. Installing it last night and today I was ready to play. It required a roller work out, since it's 14 degrees outside and somewhat icy, and while I was spinnning easy scrolling through the functions looking at my heartrate and power output, I was pumped up getting 250 watts spinning easy. I then jumped into a killer workout to see what kind of max power out put I would get. I finished up the workout and started to recall the data and all that was there was there was distance covered and the elapsed time, I thought all the functions auto started and recorded but found out that you have to push the left upper and lower buttons to record all the data. Oh well, I didn't get to see the maximum watts put out from todays work although on the positive side I'm really looking forward to my next hard workout on the rollers to see the data.
re: HAC-4 Class 101Ian
Jan 10, 2004 11:05 AM
Keep in mind the HAC 4 is virtual wattage. It knows by your weight, speed and grade what the power output would be. I have never been on rollers, so I don't know if it will equate from the real world.

I guess the question would be; what was your speed showing as? And can you do that speed on the road?
re: HAC-4 Class 101PMC
Jan 10, 2004 11:14 AM
As a comparison, my Powertap reads at 200 watts (give or take a couple watts) at around 24-24.5 mph on 3 inch Kreitler rollers with 110 psi in the tires (I'm around 73kg).
re: HAC-4 Class 101Squint
Jan 10, 2004 1:36 PM
On my Kreitler Classics (4.5" drums) with the wind unit set quite low (nearly closed) and using the easier big pulley, I get ~270W at 22 mph riding in my 39x13. I currently weigh about 70 kg though my SRM doesn't know that.

I did find that resistance varies noticeably with tire pressure.
re: HAC-4 Class 101MellowVelo
Jan 10, 2004 11:14 AM
If you want to see max watts data after a ride, the EASIEST way to see it, is to put the computer back on the bike mount & hit the bottom right button several times until you get to the wattage screen and then the bottom left button will scroll between the current power, average power & max power.

I hate to burst your bubble a little here, but the power feature on the HAC-4 is an estimate. It's pretty accurate while climbing but on flat ground it's not and often 100+ watts low - on descents it can be worse. The wattage data is mathematical function that bases wattage on speed, gradient, your weight and an assumed frontal profile. It is best at figuring wattage while climbing, but keep in mind it isn't real time, there's a 10+ second delay.
re: HAC-4 Class 101pedalruns
Jan 10, 2004 11:32 AM
I've been using a HAC-4 now for about 4 or 5 months and I'm pretty happy with it.. It is a little quirky, but for the most part I really love it. Now, don't forget to turn the recording off when done!

Like everyone say's the power output is not really accurate on the road due to wind speed/direction.. but on rollers I think it should be pretty good... The conditions would be the same everytime..
re: HAC-4 Power IssuesAsiago
Jan 11, 2004 7:33 PM
Like others have said, the HAC-4 only estimates power. I run an HAC-4 and a Powertap. The HAC-4 simply cannot accurately estimate the peaks and valleys that is your power output. Your power output changes too quickly. Now, spread that out over a long period, say a two hour ride, and it will be able to fairly accurately estimate average power provided you have correctly input all necessary information. For example, on a recent two hour ride (loop, not point to point), my HAC-4 recorded 141W average and the Powertap recorded 140W. However, the HAC-4 recorded 500-something for peak power while the Powertap recorded 980W. This also has something to do with the HAC-4's 20sec recording sample.

HAC-4 on rollers or a trainer? Nope, sorry, not valid data.

This is why the HAC-4 is not a suitable replacement for an real power measuring device such as a Powertap. The Powertap actually measures the power you are generating. Which makes the Powertap IDEAL for rollers or a trainer.