First two rides with a power meter are these numbers about right?????

Upload the TCX's to Garmin Connect - or post them online somewhere the headline numbers you've put up don't really tell anyone an awful lot. However it's unlikely you managed to average 94watts for the first ride. But we don't know much about that.

Get Golden Cheetah for the analysis, mac friendly and pretty good.

A 40km TT in a reasonably average position for an 80kg guy shouldn't need much above 270 watts maybe for the hour. It all depends on your aerodynamics not your weight though.

Ride 1

connect.garmin.com55122150Open ↗

Ride 2

connect.garmin.com55235013Open ↗

I haven't used mine for awhile so I hope I'm remembering correctly.

Make sure you've zero'd everything. I think you can also set it so that it stops recording a few seconds after the speed goes to zero - you should check that too else you'll just average in a lot of zeroes and drag that average down.

To check calibration you can do a "stomp" test. I've done this - let's see if I remember. I'm sure you can check the web for info though.

You need to be in torque mode and you apply a known weight to the pedal with the brake on so the wheel doesn't turn. The pedal needs to be at 3 o'clock to get the maximum reading. You can calculate the torque with the known weight and crankarm dimenstion and compare it to the reading.

94 watts sounds rather low to me.

I like the WKO program for data recording and analysis.

Quoted post said:

Originally Posted by murph75 [IMG]/img/forum/go_quote.gif[/IMG]

These rides are after recovering from a sickness although hopefully the average speed and power will tell me if the numbers are about right....
Details of both rides are below. If anyone can help with any of the following queries it would be greatly appreciated.

• Is this average power about right?
  
• Is there an easy way to check accuracy of the unit?
  
• What would the average power be for someone of my weight to do a 40km time trial in an hour ( I couldnt do this just trying to get a feel for what power is required for a given effort)?
  
• Riding along flat ground and a tail wind is it normal for the watts to be zero a lot of the time?
  
• What is the easiest way to share ride info on a forum such as this I have been using garmin connect but now that I have a power meter will most likely to something else (Mac friendly)?
  
• Any other pointers??...
  

As others have said the average power looks very low for those rides but as folks have also pointed out average power for the entire ride can be very misleading if you had substantial sections of coasting or drafting others. What were the speed and power relationships for your best sustained 5 to 20 minute sections of those rides?

The 'Stomp Test' mentioned above is a way to test the accuracy of the PT hub by hanging a known weight of the pedal and comparing the torque reported vs. the known torque calculated from the weight and the length of your crank arms. Some folks use their body weight which can work but it's easier to get repeatable and accurate results by using a heavy weight lifting plate in the 20-30kg range instead of actually 'stomping'. The procedure is available several places on line and even in the archives of these forums if you do a search as it's been discussed here a few times at least. If you can't find it one of us can post the steps and how to interpret the results. Note this just checks the accuracy of the hub, you can't user correct any big problems but you can at least find out if its measurements are reasonably accurate.

There's also a PT self test that Saris built into the unit. It measures the reported torque in unloaded conditions and by comparing that number to what's expected from typical good units you can get a big clue that your hub is either typical before you actually start generating power or is suspiciously out of whack from normal units. Details on the self test are available in the PT manual which is available free on line from the Saris website though I've never used a Garmin head unit so that likely complicates things.

At 70kg I've gone sub hour in a 40K TT on as little as 240 watts on a full TT bike and 270 watts on a road bike with clip on aero bars but on slower, windier days at sea level I've had to put out roughly 290 watts to just hit an hour by the skin of my teeth so it varies depending on weather, course, rider weight and as mentioned above your position and aerodynamics.

If you're riding along and putting any pressure at all on the pedals then you should be seeing power readings. A tail wind won't completely negate the need to generate power or the tailwind would have to be gale force and you'd likely be more worried about stopping than going faster. Basically moving down the road at zero watts only happens for long on descents and even then you'll see power numbers when you pedal fast enough or in a big enough gear to catch up with the wheel speed. Something is wrong if you're pedaling on flat roads and seeing zero watts which would be consistent with the low average power you're seeing for your rides.

Sounds to me like you've got an issue with your PT setup. You mentioned that you 'calibrated' your hub but since that's not possible I take it you are referring to zeroing the torque before riding which is something you should do before every ride as the torque readings drift over time and across temperature. If you didn't actually zero the torque on your hub before those rides (which is a possibility since you also posted a question about the Garmin and torque readings) then definitely figure out how to do this and do it before you ride. Again the manual explains how to do this at least with the Saris CPU.

Good luck,
-Dave

Don't turn auto-pause on, that's a very bad idea - pauses are genuine data (stopping for 30seconds at a stop light doesn't make the 30seconds disappear from from your physiology it needs to be included.

I suspect your calibration is off - your watts particularly for the first ride are a little low to be realistic if you're 80kg. Please ensure you zero the PT correctly and see if you get better numbers and attempt a stomp test to confirm if it's off or not. It may need to go back to paligap for servicing.