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!

This week I decided to have a bit of fun with the mailbox and mix it up some. As many of you know, the founder of Slowtwitch is Dan Empfield - thus, when he has a question - I'm more than happy to answer. It turns out, Dan has lots of interesting questions. So here's a small collection of my favorite questions Dan has e-mailed me, for your electronic gadget reading.

1) Cable Charging Mashup
2) Power Meter Head Unit Options
3) Best Triathlon Watch Bang for Buck

Question #1: Cable Charging Mashup
From Dan-

"I'm currently "enjoying" a mini explosion of microelectronic gadgetry in my office: Go Pro camera, Garmin FR205, Garmin Edge 500, Timex Global Trainer, some other stuff, and I fear I'm losing track of which cable goes to which device.

In particular, there's the USB Type A to mini USB type B cables that a lot of these devices seem to use. Then there are the USB to 110v inverters.

What do I need to be watch out for? Are all these interchangeable or not? I wonder whether this is a good topic to write about, if you haven't done so already."

You can pretty much mix and match everything there without any issues. There are some occasional amperage differences, but the worst thing you'll find with USB devices is that one will just charge slower than the others. I've long since ignored what cable/adapter/converter goes with what item and simply grab a few for my trips and mix/match as I see fit.

What we are seeing now though is MicroUSB starting to catch on a bit more. For example, the new G5 GPS pod for the Polar RCX5 is MicroUSB, same with the new Joule GPS unit. And we're also seeing some companies going the route of the caseless USB-A as well, like the Nike+ Sportwatch GPS and the FINIS AquaPulse. Both of these have the electrical portion of the USB port, but lack the outer metal case. They instead plug straight into a computer.

I suspect over time things will largely go MicroUSB for most sports devices. The only bummer about MicroUSB is they're easier to snap/break than MiniUSB - especially if a cable is left in the device and tossed in a backpack. I've lost a few MiFi wireless access points that way…

Question #2: Power Meter Head Unit Options
From Dan-

This one's not quite exactly an exact quote, because it was a phone call, but here's the gist of it:

"I've got this large pile of devices, but I'm not sure which ones are best for connecting to power meters. Many of them say that they're ANT+ compatible - and my power meter is too, will they all work with my power meter? Is it complex to setup?"

While many devices are ANT+ and fully interoperable, only devices that support the ANT+ power meter device profile will support hooking up with a power meter. Think of device profiles as standardized ways for devices to communicate within the ANT+ world. Each device class (i.e. heart rate strap, cadence sensor, power meter, weight scale, etcÉ) has a separate ANT+ device profile. For example, the Garmin FR205 does not support the ANT+ power meter device profile, primarily due to being a running watch. But the Garmin FR310XT does support the power meter profile. There's no hardware differences that allow one devices to support certain sensor types - it's merely a software decision.

Looking at the popular standalone devices, the Garmin Edge 500 & 800, CycleOps Joule, Garmin FR310XT and Timex Global trainer all support the ANT+ power meter device profile. Though each one implements features around it slightly differently. In fact, until recently the Garmin FR310XT lacked many features that it's bike siblings the Edge 500 and Edge 800 had. But this has been slowly rectified over the past few months via software updates and almost every power meter features that the Edge units had is now over on the FR310XT. Personally, I think that the Edge 500 makes the best bang for your buck as a purely cycling computerÉbut the new Joule GPS coming out here shortly will definitely give it a run for its money. Once I get a product unit in my hands it'll be really fascinating to do a shootout between the equally priced units.

Question #3: Best Triathlon Watch Bang for Buck
From Dan-

"I know you've written extensively about the Timex Global Trainer, and others. What's the best bang for the buck, and just bang period? Polar RCX5? Garmin FR310XT? Timex Global Trainer?"

I think it largely depends on how much buck you've got - but by most metrics the FR310XT is the best bang for it's buck - and best bang. The reason is that while the cheaper TGT includes many of the major features of the FR310XT at about half the price, it lacks many of the polish features that the FR310XT has. Further - and most importantly, it continues to suffer from GPS accuracy issues that still haven't been addressed over a year later. I've long since said that that if Timex can resolve the GPS accuracy issues though, they'll have themselves a much more competitive watch - even if the polish items aren't all there.

When I talk about polish items, it's features like power meter head unit configuration (no PM config in TGT), openwater swim mode, ability to use the footpod for treadmill use, ability to link up with weight scales, etc. In the end, it's these extra features that the TGT lacks that puts the FR310XT ahead.

On the flip side you do have the Polar RCX5 unit - which is very competitive if you're already a Polar user with existing Polar gear. The only challenge with the RCX5 unit is that it's not ANT+, and instead uses proprietary Polar protocols. And while this is good for past Polar users, it's not ideal for the rest of the world (especially cycling) that uses ANT+ for components like power meters (which the RCX5 doesn't support). But by the same token, the RCX5 is the ONLY triathlon focused watch that can read your heart rate underwater and record it - which is definitely valuable for some folks. Additionally, by separating the GPS pod from the watch they've obtained crazy long battery life (many months) - which makes it an ideal sleek day to day watch.

Recent Mailbags:

Weekly Mailbag - June 10th, 2011
- How to create mile alerts w/o using auto-lap?
- Wearing heart hate strap during races
- HTC Android Phones that have ANT+ Capabilities?
- Garmin Forerunner 310XT new power meter firmware updates

Weekly Mailbag - June 5th, 2011
- To use or not to use elevation correction
- Heart rate measurements while underwater combined with distance
- How to setup run/walk intervals

Weekly Mailbag - May 30th, 2011
- Is Edge 500 reliable with PowerTap?
- Garmin FR310XT and where to wear it during swim
- Training with Heart Rate Resources

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.]