Author Topic: Anyone using a Powertap hub with an Edge 705?  (Read 6107 times)

Anyone using a Powertap hub with an Edge 705?
« on: 27 February, 2012, 09:00:38 am »
Newbie questions follow......

I've just acquired a Powertap G3 and I'm trying to learn how to use it with an Edge 705. I've tried it only twice, so I might be a bit premature, but it seems reluctant to show power readings when starting the ride until I drilled all the way down through the Edge menu (Settings/ANT+Sport/Accessories) and hit the "Restart scan" button. Does anyone know if this is necessary each time I use the Powertap?

I did have to change the battery in it between my first attempt and the second; perhaps this was the cause?

Also, what's the best analysis software? TrainingPeaks seems to be the recommended stuff but is there anything better?

inc

Re: Anyone using a Powertap hub with an Edge 705?
« Reply #1 on: 27 February, 2012, 10:55:46 am »
I am not sure what you mean, the hub and hrm need to matched to the 705 only once (and after changing the hub/hrm battery) After that after turning on the 705 it will detect the hub and hrm within seconds. Both the Garmin and Powertap sites give detailed instructions.  Golden Cheetah is free and good  http://goldencheetah.org/

simonp

Re: Anyone using a Powertap hub with an Edge 705?
« Reply #2 on: 27 February, 2012, 11:04:04 am »
It works for me.

Try doing things in this order: spin the powertap wheel to get it transmitting then turn on the 705. I don't recall really having to do this though.

Re: Anyone using a Powertap hub with an Edge 705?
« Reply #3 on: 27 February, 2012, 11:13:06 am »
If you PM Greenbank he may be able to help with any specific questions, I am pretty sure he has this setup.

Re: Anyone using a Powertap hub with an Edge 705?
« Reply #4 on: 28 February, 2012, 07:29:07 am »
Thanks guys. It seems to be OK now; I think it was the battery change between sessions that confused things, as inc. suggests.

I'll take a look at Golden Cheetah

amaferanga

Re: Anyone using a Powertap hub with an Edge 705?
« Reply #5 on: 28 February, 2012, 03:44:16 pm »
Couple of things to add: turn off autopause on the Edge, turn on zero averaging (this only affects the numbers displayed on the device and not the data you download to analysis software, but having zeros excluded will massively inflate your power numbers on any normal ride), turn auto-zero on and always manually zero at the start of a ride.

Does the G3/705 pairing show you the zero offset value when you do a manual zero or does it show the device ID?  If it shows the zero offset then this should be 512 +/- 12 (assuming its the same as for the old Pro+ / SL+ models).  You can check for drift due to e.g. temperature changes during a ride by looking at this number (more relevant for turbo rides where you don't coast since on road rides if you coast the Edge should reset the zero point if it has changed).

Re: Anyone using a Powertap hub with an Edge 705?
« Reply #6 on: 29 February, 2012, 09:01:24 am »
Couple of things to add: turn off autopause on the Edge, turn on zero averaging (this only affects the numbers displayed on the device and not the data you download to analysis software, but having zeros excluded will massively inflate your power numbers on any normal ride),
Whoa  ...! Steep leaning curve ahead!
OK, I've turned off the Autopause and switched on the zero averaging. I'm not sure what the latter does but from what you've said I guess it sort of smoothes out the data to eliminate such as freewheeling periods - ?

turn auto-zero on and always manually zero at the start of a ride.
I can't find these options in the Edge menus (unless you refer to Resetting the data in the Trip Log?)

Does the G3/705 pairing show you the zero offset value when you do a manual zero or does it show the device ID?  If it shows the zero offset then this should be 512 +/- 12 (assuming its the same as for the old Pro+ / SL+ models).  You can check for drift due to e.g. temperature changes during a ride by looking at this number (more relevant for turbo rides where you don't coast since on road rides if you coast the Edge should reset the zero point if it has changed).
Nope, sorry, I'm completely lost now! Does "offset value" refer to the figure I get when I hit "Restart scan" in the Accessories screen? (I don't have the Edge in front of me as I type, so I might be recalling this wrongly.)

I'm also unfamiliar with "drift" - as a newbie and without any documentation with the Powertap, I'm somewhat in the dark about all this, sorry!

amaferanga

Re: Anyone using a Powertap hub with an Edge 705?
« Reply #7 on: 29 February, 2012, 10:08:07 am »
Whoa  ...! Steep leaning curve ahead!
OK, I've turned off the Autopause and switched on the zero averaging. I'm not sure what the latter does but from what you've said I guess it sort of smoothes out the data to eliminate such as freewheeling periods - ?

With zero averaging 'off' then the displayed power will exclude zeros.  So if you rode for say 10 minutes at 200W then coasted for 10 minutes your average power for the 20 minute period would still be 200W.  That's obviously not the true average and so having zero averaging 'off' just inflates the numbers and deceives you into thinking you're putting out more power than you actually are.  But like I said, this only influences the number displayed on the Edge and not the data downloaded to analysis software such as WKO+ or Golden Cheetah.

I can't find these options in the Edge menus (unless you refer to Resetting the data in the Trip Log?)

Nope, sorry, I'm completely lost now! Does "offset value" refer to the figure I get when I hit "Restart scan" in the Accessories screen? (I don't have the Edge in front of me as I type, so I might be recalling this wrongly.)

Go to Settings --> Bike Settings --> Bike 1 (or whatever you've named your bike profile) --> ANT+ Power and select 'Calibrate'.  You need to be stationary and have no load on the pedals.  Wait a few seconds and a number will be displayed which will either be the PowerTap ID number or the zero offset value I referred to which should be 512 +/- 12.  The auto zero box should also be ticked - if not then scroll down to it and hit enter.




I'm also unfamiliar with "drift" - as a newbie and without any documentation with the Powertap, I'm somewhat in the dark about all this, sorry!

There's a steep learning curve like you said, but you'll get there.  If you haven't already I'd recommend you buy 'Training and Racing with a Power meter' by Hunter Allen and Andy Coggan.  This won't tell you how to operate the PowerTap, but it will tell you how to interpret the data you get and therefore make the most out of owning a power meter.  The Google Wattage list is also worth joining for discussions of all things to do with training with power meters.   There are a lot of experts on the list (and plenty of folk that think they're experts) and some pretty advanced stuff is discussed, but there's also loads and loads of really useful general information.

Re: Anyone using a Powertap hub with an Edge 705?
« Reply #8 on: 29 February, 2012, 04:28:06 pm »
Just back from a five hour session - loaded the powerfile into TrainingPeaks (trial download) - now have lots of very impressive graphs to be baffled by (well, they'd be more impressive if some of the levels were a lot higher!)

Seriously though, I have a copy of the Allen & Coggan book - it was reading this that persuaded me to get a power meter. It's a bit chicken and egg - to get the best out of the book, you need a power meter and vice versa - stating the obvious really. Now that I have the stuff, the hard learning starts (as does the hard riding!)

I found the zero offset value when I started the ride this morning; as you say, it came up when I hit the "Calibrate" button - it showed 511. And as you say, the auto zero box was there too and ticked.

I've Googled for "Google Wattage list" and found Cycling Forums.... Power Training thread. Presumably this is what you're referring to? Looks like lots of reading; will keep me out of mischief!

Many thanks for taking the time to respond; much appreciated.

simonp

Re: Anyone using a Powertap hub with an Edge 705?
« Reply #9 on: 29 February, 2012, 05:10:21 pm »
I used my power meter for the first time in well over a year last weekend. I am going to use it a bit this year and not ride 100% fixed gear when I'm not on the tandem.