CompuTrainer-Quark power differences & WTO+ Garmin uploads

glenncook

Two questions.

(1) Being new to power training on the bike, I noticed a 20-30 watt difference between my Quarq power readings and the readings on CompuTrainer. I calibrated the CompuTrainer as prescribed and zeroed out the Quark before the rides. Running them at the same time produces big differences. Am I doing something wrong or is there an easy explanation?

 

(2) I am downloading the power readings from the bike (both CompuTrainer and Quark) to WTO+ 3.0. When I try to download the run information from my Garmin 310XT wirelessly, the device is not recognized by WTO+ uploader. Can I upload both bike and run info to WTO+ at the same time?  Again, what is the solution?

david ware

Hi Glenn:

Without getting too technical, many others can do that, the readings are going to be different because they are measured differently. I have the same set up as you and in WKO have both "Dave" and "Davetwo." Dave is the Quarq/Garmin data and Davetwo is for the Computrainer. Do not be concerned that there are differences, the important thing is that they be internally consistent...Q/G should be consistent with itself and CT should be consistent with itself. I can double check. If I know there should be a 15W spread by comparing the data; if it is more than that, then I know there is a problem. Dave

Kevin Walter

Are you using the Garmin as head unit for the Quarq and able to download your bike data? If yes then I don't know why run data isn't working while bike is. If not then check to be sure that ANT agent is installed properly with Garmin Connect and all drivers updated from Garmin. Device Agent doesn't directly download from the device, it just takes the file as already downloaded by ANT agent and converts it to WKO format. You can do the same thing manually using the import command in WKO and browsing until you find your .tcx file stored on your harddrive.

Hope this helps.

dboyle

Mr Ware has it correct

 

In cars there are two horsepower ratings, at the crank and at the wheels. They are usually 10-20% (depending on the car) different, with the wheel rating being lower. Why? Drivetrain (gears, transmission) robs some of that power.

 

Same thing is happening here, quark is crank based, computrainer is at the wheel.

 

I would worry if the ratio is flucuating, so if say at the beginning of the ride it is 10% and at the end it is 15-20% difference than I would worry. Keep in mind due to the differences in sample rate etc you can't pick a specific data point and analyze. Just look at both and try to do the math in your head while you are doing intervals

 

I used this method to determine that my ergomo was dead, slapped leigh's powertap on the bike and went for a ride and the numbers didn't align at all, so ergomo got thrown out.

 

-Dave

glenncook

Thanks guys for the responses. I guess I am just at the beginning of this big learning curve. One step at a time--your advice makes it a little easier.