Tandem Cycling - Garmin question

We recently got a Garmin Edge 305 for the stoker & she really likes it. I've read most of the manual but have a question:

I assume there is a limited memory in the unit. We have done about 6 rides with it and have uploaded them to a computer. Does the action of uploading the data erase it from the unit or do we have to deliberately do so? If the unit is set to "smart" data recording, how many hours can be stored in it?

The question arises because we are leaving on a 6 day ride and won't be able to upload the data after each day.

Thanks.

Page 43 - 46 of your manual... HISTORY

In short, the Garmin unit will continue to store history until the unit is full (I believe 1,000 laps / 2 years is the cited capacity), at which point it will then start to overwrite the oldest data.

The unit only records data to memory when the timer is running so unless you start the timer, nothing gets logged.

You can, of course, choose to clear the memory after downloading to your laptop.

My SigmaSports HAC4 operates in much the same way, it just doesn't have nearly as much memory as Debbie's 305.

http://www8.garmin.com/manuals/967_OwnersManual.pdf

p. 62

3.5 hours recording every second, more with smart recording, old gets overwritten by new once memory full.

Smart recording makes for a lot of space; you ought to be fine. I've used mine for several 5 and 6 day trips without any hint of worries.

Don't forget to pack the charger!

Thanks!

Please note that there are some practical limits besides memory. Battery life on the 305 is not quite up to Garmin's quote, the longest I have had a unit record was just a few minutes over 10 hours. Also the limit on time is based on the number of data points not really a time limit. About 13000 trackpoints can be stored in any single timed event, smart recording only records when direction or speed changes but it averages about every 3-4 seconds about 10.5 - 14 hours. The remaining memory is segmented as history storage and course storage. They do not overlap like the 705, in other words it is not a big pool of memory, it is preallocated. Storage is longer as you can store several timed events on the unit before it will start overwriting.

To be safe you could take the first couple of the six days and convert it to a course in the Garmin, then erase it from the history. Problem with this approach is that you will lose any heart rate data if you are also using the HRM.

For more info:
http://forums.motionbased.com/smf/index.php?topic=5365.0 - Saving Tracks
http://forums.motionbased.com/smf/index.php?topic=5802.0 - Amount of memory available to save courses
http://forums.motionbased.com/smf/index.php?topic=2579.0 - Edge 305 memory

Smart recording makes for a lot of space; you ought to be fine. I've used mine for several 5 and 6 day trips without any hint of worries.

Don't forget to pack the charger!

I've not been that that fortunate with my 305, even on the smart recording setting. I've used it on 4 week-long trips, and lost at least a day on 3 of those. On the fourth, I took a laptop and uploaded at mid-week and managed to not lose anything.

There is a difference between how long you can record for a single ride and how much storage is available to store rides. I believe I read that resetting after about 12 hours was recommended however, I had been resetting my 605 every 10 hours up until recently when a patch was released to remove the limit. I do not know if there has been a similar patch for the 305 but it would be worth checking on.

My last ride was over 16 hours and it doesn't appear that I have lost any according to Ascent, however I have not been able to get the ride to upload to Motionbased yet. I might have to split the ride to get it to work.

Hold down the start/stop button to reset.

As for battery time, the 605 outperforms its advertised capacity. I have gotten well over 15 hours.

There is a difference between how long you can record for a single ride and how much storage is available to store rides. I believe I read that resetting after about 12 hours was recommended however, I had been resetting my 605 every 10 hours up until recently when a patch was released to remove the limit. I do not know if there has been a similar patch for the 305 but it would be worth checking on.

My last ride was over 16 hours and it doesn't appear that I have lost any according to Ascent, however I have not been able to get the ride to upload to Motionbased yet. I might have to split the ride to get it to work.

Hold down the start/stop button to reset.

As for battery time, the 605 outperforms its advertised capacity. I have gotten well over 15 hours.
The 305 does not have the ability to record more than 13000 track points for a timed event regardless of firmware revision. Most users doing multi-day tours will start overwriting history on day 5 or 6 hence the link to the Motionbased thread and suggestion to take the first couple of days and save them as courses.

Motionbased has issues with rather large files, it becomes more apparent when you try to use 1 second recording. If you are using a powermeter 1 second recording becomes an essential component in your route, but this last statement does not apply to the 205/305.

Longer recording time and 1 second recording, as well as longer battery life are why I 'upgraded' to a 705. The PM will be next years tool used to train better, train for what I just don't know, but it will be better! :lol:

The 205/305 battery life is well documented on Motionbased forums.

Our 305 came with a crank & wheel sensor. We don't monitor cadence. If I remove these sensors, will there be more memory available for time, distance, altitude, heart rate, etc?

Our 305 came with a crank & wheel sensor. We don't monitor cadence. If I remove these sensors, will there be more memory available for time, distance, altitude, heart rate, etc?

No you are still limited by the number of track points. The only thing I know that actually lowers the number of track points you can record is if you have markers added to the route. I would still suggest that if they are relatively full days that you take the first two or three and convert them to courses then erase the history so that you can make room for the last days. Unless there is some way to download the data after a few days.

No you are still limited by the number of track points. The only thing I know that actually lowers the number of track points you can record is if you have markers added to the route. I would still suggest that if they are relatively full days that you take the first two or three and convert them to courses then erase the history so that you can make room for the last days. Unless there is some way to download the data after a few days.

One other note here: I only offer this as true because I've had mine on several multiday trips without difficulties. Total number of track points has been mentioned as a limiter on a single timed event. I have always made the individual days separate timed events, which would move them to history and so should help with single-event trackpoint issues. I'm don't know this definitively, but as there are currently dozens and dozens of rides in my history and I've never had a problem on weeklong tours, it seems to be the case. If you later wanted to stitch the separate days into a single 'event' once downloaded, that would be easy enough with the GPX files and a text editor.

Also, not recording HR and Cadence WILL help with memory, at least to some extent. As noted, a trackpoint is created each time there is a change to recorded status. If you were to ride a straight, flat road at a constant speed, it would record few data points. However, if you rode the same course and speed, but constantly shifted gears, your cadence (and a few seconds later, HR) would continuously change, requiring additional data points. Similarly, if you were sitting still as your HR came down during a recovery, you would record a set of trackpoints even though not moving.* Odd as it seems, HR and cadence values are elements of a trackpoint, along with location information. Convert a ride to gpx/xml to see this explicitly.

*Depending on the device settings for recording while stopped/moving slowly.

I'm don't know this definitively, but as there are currently dozens and dozens of rides in my history and I've never had a problem on weeklong tours

This is the point I was getting at earlier. For longer one day rides, resetting the ride so it goes to history and starting again should be done about every 10 hours with smart recording. On multiple day events, I would reset every day at least.