Hello, welcome to the Weekly Mailbag. I'm Ray, from DCRainmaker. com. If you've ever searched for reviews on sports technology - you've probably come across my site. I write about my triathlon/running training in general, along with sports technology and whatever else seems interesting to me. I started the Weekly Mailbag series earlier this spring as an opportunity to share some of the answers of the many e-mailed questions I get each week.

If you enjoy what you find here, then feel free to click the links to find even more in depth information on each topic. And if you have any questions, you can always e-mail me directly. Thanks for reading!

1) Comparing Garmin GTU-10 vs Spot Tracker
2) Creating CompuTrainer courses from GPS files
3) Heart Rate Strap Combo Platters

Question #1: Comparing Garmin GTU-10 vs Spot Tracker
From Jamie-

"Had a question for you about the Spot Tracker vs the Garmin GTU 10. I have the original spot tracker but don't use it too often. That $100+/ year price tag has been getting to me. Seems the GTU 10 has more useful features about the notification etc. If you were choosing between the two what would you choose? I know your GTU10 review is coming but for 2nd year @ $50/year it seems the Garmin might have a couple more features?"

They're both similar, yet entirely different devices. Kinda like comparing lemons to limes. The Spot Tracker, like the GTU 10, uses GPS to determine your position. However, the Spot Tracker uploads your position to the internet via low earth orbit satellites. Whereas the GTU 10 uses conventional cell phone networks to update your position, similar to how a standard cell phone would connect. This is one reason why the Spot Tracker folks tend to focus on adventure scenarios in areas where cell phone service doesn't work (rugged mountains, oceans, etc…), and also why it has the 911 button built in. While the Garmin GTU targets users in environments where cell phone service is constant - such as car or person tracking in cities and cell phone friendly areas.

The two services are also different. Garmin's site and app are more about notifying you that a given event has occurred, for example crossing a geofence (specified area). While you can certainly lookup the location of the GTU at any time, the website currently requires the person doing the lookups to have your username and password to access the units location. Whereas the Spot site is aimed at letting friends and family easily track you on a shared webpage from any internet browser, they need only have the URL to lookup your location (you can protect it too though). Both services have history functions, with the Spot history being a bit more versatile and easier to sort/filter/export.

From a triathlete or cyclist standpoint though, the GTU 10 is probably the better option if you're in cell range and if you're in a race situation. The unit is about the size of a pack of gum, whereas the Spot device is 1-2 packs of cards. Further, the Spot device only updates every 5-10 minutes (depending on version), whereas the GTU 10 can go as low as every 30 seconds. Both are IPX7 waterproof, so can easily standup to casual water. Unfortunately, neither device at this time has ANT+ capability built within it - so the data is purely location based.

Finally, for a really innovate look at how to use the GTU 10 for tracking runners in marathons, check out this post.

Question #2: Creating CompuTrainer courses from GPS files
From Steve-

"My wife and I are building an Indoor Cycling Studio with a heap of CompuTrainers but I have a question. Is it possible to upload the (say for instance MS150 ride from Houston to Austin) to the CompuTrainer?"

Yup, you can use the CompuTrainer Course Creator software to take the GPX file from the Garmin Edge 500 and create a course for the CompuTrainer. In fact, it used to be that this software application cost money, but now CompuTrainer gives it away for free. When the new RacerMate One software suite releases here in the near future, it'll include this functionality inbox, allowing you to quickly ride GPS created courses on the fly without any conversion - a nice addition.

Also note that even if you don't have a GPX (GPS) file handy that you created yourself, you can still use this feature. Simply head on over to Garmin Connect and search for the activity/route/event you want. For virtually every event run these days someone did a previous year of it with a Garmin device. And in doing so, those course files are available online for you to search and download. And failing all that, you can simply head over to MapMyRide, create the course and then download the GPX file…mission accomplished.

Question #3: Heart Rate Strap Combo Platters
From Jeff-

"I have question regarding Polar & Garmin HR strap compatibility (or lack thereof). I recently changed PMs from SRM to Quarq (w/Garmin Edge 500) and previously my coded Polar HR strap worked with my SRM PCV and my Polar RS200. Now that I am using the Quarq with Garmin 500 I have to use the Garmin HR strap on the bike and then change straps out for the run to use my Polar. Do you know if there is a strap that can be used for both coded Polar HRMs and ANT+ Garmin's?"

Hi Jeff. Unfortunately, no such strap yet exists. There's a potpourri of different combo straps out there today, but none that share both ANT+ and conventional HR transmission (or Polar WIND coded protocol). For example, there's Polar straps that have the following:

A) Combo Polar & Nike+ strap
B) Combo Polar & Bluetooth strap
C) Polar 5kHz & Polar W.I.N.D. Hybrid strap
D) Standard Polar Coded and Uncoded straps

Even on the Suunto side while they have combination straps that do both ANT and conventional 5kHz un-coded, it just doesn't do ANT+. Which makes it largely useless to everyone except Suunto users. ANT is really only used by Suunto, whereas ANT+ is used by everyone (including the Garmin units you noted).

The irony here is that this is fairly commonly requested, yet I haven't seen anyone bridge this gap - especially since compared to adding in some of the other protocols, adding in the conventional 5kHz one is pretty easy. Hopefully we'll see one of the umpteen ANT+ heart rate strap vendors add this functionality.

Recent Mailbags:

Weekly Mailbag - May 8th, 2011:
- Connecting multiple ANT+ units to a single HR strap
- Screen protectors for Forerunner devices
- HED3 wheel speed sensor magnet options?

Weekly Mailbag April 26th, 2011:
- Detailed comparison between FR310XT and FR610

Weekly Mailbag - April 19th, 2011:
- Bluetooth Heart Rate Strap Monitors
- ANT+ Cell Phone Client and App Options
- Review of smartphone clients

You can find all past Slowtwitch Mailbags here, and all prior ones here.

[Editor's note: our capable editor-at-large for electronics Ray Maker is the publisher of the online sports tech blog DC Rainmaker, one of the top-ranked sites by Google for extremely in-depth reviews of advanced GPS and Heart Rate Monitors for triathlon, cycling, and running.]