Wednesday, March 11, 2009

Cycling Computers...

When I bought my bike last August, I went with a relatively basic cyclocomputer (Cateye Strada Cadence) to keep costs down. It does a good job at providing me with information during the ride, however it has no mechanism to store that data so analysis of my cycling sessions is a little difficult. Right now, I use my Polar RS800sd to monitor my heart rate, and simply hit the lap button every 2.5km to provide me with a basic record (giving me average speed over those intervals). This works on the trainer, but it's a kludgey way of handling things and will become much less practical when I get back on the road (and can't monitor the display as closely).

Being the data junky that I am, and given that cycling has worked well for me over the last little while, I'm now looking to replace that unit with something more sophisticated. While there are a few things that I could upgrade on the bike, at this juncture I'm still the weak point in the equation so being able to better monitor my training will likely have more effect than any other equipment changes. I'd like to get that done now, so I'll be fully familiar with it and ready for the new season once the weather picks up a bit.

The Contenders

With that said, the market for these devices is a whole lot more complicated than their running equivalents so figuring out which way to go isn't easy. When I selected my RS800sd over Garmin's Forerunner 305, the choice was relatively easy as the former generally has a functional superset of the later, so it was just a matter of figuring out whether the Polar was worth twice as much. With cycling computers, however, there are multiple choices and each of them have some significant advantages over one another so any selection is going to be a compromise.

As I haven't made a selection as of yet, the purpose of this post will be to (a) collect my thoughts on the matter and (b) hopefully to provide information for anyone else looking at making a similar choice. Once I do get something, I'll be sure to post a review of it as I did with the RS800 but for the time being I'm simply discussing my thought process prior to figuring that out ;)

Polar RS800CX

The easiest choice would be to send my RS800sd in to Polar to have it upgraded to an RS800CX which, amongst other things, adds support for their cycling sensors. This would give me a singular device that would work for both running and cycling, and would offer some significant advantages in multi-sport events where I may need to record information from both. As I understand it, one does have to fiddle with the controls to switch sports, but that's not likely a huge issue (as switching between two discrete devices will have the same issue).

The downside to this choice, however, is that the RS800CX is a wrist mounted device so it's not nearly as convenient as the stem-mounted solutions that the other options offer. Aside from being harder to operate, this also means that reading the display would be a much more distracting affair. Polar does offer a mechanism to mount the watch on the handlebars, but this is a bit kludgey and given the issues that I've had with my wristband I'm not sure how much I'd trust it. The other catch is that the RS800CX doesn't have any capacity to work with a power meter, so adding that down the road would mean a second piece of electronics cluttering the headset.

The other catch to this option is I'm not sure whether Polar Canada offers this service, nor do I know exactly how much it costs. The decision as to whether the upgrade is available in a market appears to be left to the national distributor, so not everyone can get this done. I'll have to give them a call to figure out, however as this option isn't really at the top of my list right now I haven't gotten around to it as of yet.

Polar CS600/CS600X

The natural choice for my current situation would be Polar's CS600, which is the cycling analog to my RS800sd running computer. It uses a similar interface, the same software package and shares some of the sensors with what I've already got. In addition, Polar offers this unit with a simple power meter that, when combined with the computer, is within my price range. As the CS600 uses a user-replaceable button-cell battery like the RS800, it also means that I won't have to mess around with charging batteries (or about aging cells bricking the device down the road) and can easily carry a spare with me at all times.

Additionally, if I were to upgrade my watch to the RS800CX down the road, the two devices could record data simultaneously. For multi-sport events like the Triathlon, this could potentially be a significant boon as it would (a) provide redundancy, and (b) allow an uninterrupted log of both the cycling and running legs of the race. With that said, having both the CS600 and RS800 upgrade would likely be more expense than it is worth.

The downside to the CS600, however, is that their use of proprietary communications protocols means that it will only work with their own power meter. While I applaud them for the out-of-the-box thinking on it's design (it is basically a guitar pickup that monitors vibration in the chain), the indirect method of measuring power (vs the strain gauges used in other offerings) is prone to outside influences (eg road vibration) and it isn't as accurate. With that said, it is by far the least expensive way to get power measurement, and as I can't really justify a PowerTap or SRM as of yet, it is better than no data at all. Further, as Polar designed the power meter to explicitly work with this head unit, it is a much more elegant solution than what most of the other firms offer.

Adding to this complexity is that the CS600X has just been released, but doesn't appear to have made it to the retail channel as of yet. This model adds the capacity to work with the optional G3 GPS pod, and can store a tracklog of the route taken alongside with the speed and cadence data captured by the dedicated sensors. In addition, it more than doubles the quantity of memory available in the device - even with the extra GPS data, it can still store telemetry for a longer period of time than it's predecessor. Naturally, as it's a new product prices will likely be very close to the MSRP which is significantly higher than the street price that the CS600 has been selling at.

The other caveat is that, at least with the CS600 model, Polar Canada wasn't carrying the model bundled with the power meter. Back in December, I actually went out with the intention of buying one - but as I couldn't find that SKU anywhere in this country, I had to reconsider my options. Hopefully they've changed their minds with the CS600X, but if they haven't then that changes the equation slightly (as it basically eliminates one of the major advantages of this model, as buying the power sensor separately is too expensive for me to justify). Importing it from the US is one option, however it appears that any warantee issues would have to go back to Polar USA so that's a bit of a risky proposition.

Garmin Edge 705

An extremely impressive bit of kit, the Garmin Edge 705 offers a number of features that no competing solution provides. Most notably, with the purchase of optional maps, it can double as a navigation device which would be a pretty significant aide when doing long rides out in the middle of nowhere. While the route guidance feature is a bit sketchy, the ability to pull up a map on demand and figure out exactly where you are could be extremely useful. Further, the large colour display provided for this function also allows you to display up to eight pieces of information at any given time (vs 3 on the Polar) so less button pushing would be required when out on the road.

The use of a micro-SD flash memory slot also means that this product has significantly larger capacity to store training data before it must be uploaded. The onboard rechargeable battery limits any individual ride to about 13 hours (Garmin quotes 15h, but most reviews seem to indicate 13h is more typical), but that is still significantly longer than the 3h20m recording time of the CS600X with all options turned on (5h40m without GPS). The downside to this, however, is that the battery is not field replaceable, so as the cells age this life will begin to fade. It also means the annoyance of having to deal with battery charging (vs just grabbing a new battery every six months with the CS600X).

In addition to this, Garmin's use of the open ANT+Sport protocol for communication with various sensors means that it can double as a head unit for most aftermarket power meters (including PowerTap, SRM and Cinqo products). These sensors use strain gauges to measure power output directly (PowerTap at the rear hub, and SRM and Cinqo at the cranks), so they are more accurate than the indirect sensors that Polar uses. The downside, however, is that the cheapest of these options costs more than $1000 on it's own, so on top of the price of the Garmin (~$600) that's well outside of my range. While power measurement isn't really critical, it is something that would be very helpful at this stage of my training.

The catch, however, is that using this device would mean having to use different software to analyze the resulting telemetry. Aside from the annoyance of dealing with two pieces of software to do the same thing, it also means that my training data for the two sports would be separated and attempting to analyze things in a holistic manner would be difficult. There are some aftermarket packages that can work with files from both devices, however from what I've seen they don't seem to offer all of the functionality that Polar's excellent ProTrainer software can provide. With that said, I've done some digging on the file formats used by both products and I might consider writing something up to convert the Garmin files into something that Polar's software can read.

The other thing that concerns me with the EDGE is that there appears to be some stability issues with the firmware used in the device. This product is a much more complicated device than those offered by Polar, meaning that there are a lot more things that can go wrong with the software running on top of it. Garmin, unlike Polar, offers periodic firmware updates to address issues as they come up, but they don't appear to have ironed everything out as of yet. While I can certainly deal with some quirkiness, any possibility of losing training data is a catastrophic defect in a device like this. Unfortunately, internet-based fora tend to over-represent the population that is having trouble with a product so it's difficult to tell if these are isolated issues or problems with the underlying design.

Lastly, the HRM strap that Garmin provides is not capable of recording R-R heart rate data like Polar and Suunto's offerings. This isn't a huge thing, but there are a number of aftermarket analysis products (such as FirstBeat) that can use this data to aide in training. Naturally, the per-second data that Garmin does provide is significantly more important, however the loss of this additional information is a bit of a liability. The other catch is that Garmin's HRM straps use hard plastic/metal sensor pads rather than the textile pads used by Polar, so it's likely to be less comfortable than what I've got.

With that said, this last defect could be addressed in future firmware upgrades by simply adding support for Suunto's HRM straps. As they use the same ANT+Sport protocol as Garmin, the hardware that is necessary for this is already there - it's just a matter of adding the necessary firmware to communicate with these devices and store the additional data to file. I definitely wouldn't mind paying for another strap to get this functionality back, but unfortunately that isn't an option at this juncture.

Suunto T6c

Not really a front runner, but something that I am peripherally considering. Like the RS800CX, this is a watch-based unit and carries the same caveats. The advantage that is has over the other options, however, is that it's better suited to multi-sport events. Primarily, Suunto offers an optional 'memory belt' HRM strap that stores heart rate data onboard in addition to transmitting it to the wrist unit. As such, it is the only product on this list that can provide heart rate data from swimming. Further, the T6c also has the advantage of seamlessly switching between different sensors during a session, so no user intervention is required to go from swim to bike to run.


Ideally, a device with the Garmin's hardware, firmware and software built by Polar and Suunto's sensor suite would be ideal - but unfortunately such a device doesn't exist ;) As such, I plan to continue digging for more information on these different products and try to figure out what the best course of action is for me at this juncture. At this point, I'm leaning towards the CS600X, but I could easily be swayed in other directions should I find compelling information on the matter.

I might end up picking up a Suunto memory belt either way if I do get into swimming, as it can be used independently of their watches and doesn't cost that much. I'll have to write something up to get that data into Polar ProTrainer, but as the data is structured in a similar way that shouldn't be a big issue.

1 comment:

  1. Hi,

    Chris from Polar USA here.

    It seems like you really did your research! If you need any questions answered at any point to help you make an educated decision please let me know. Although it sounds like you have that all taken care of!

    Ride safe

    Chris @ Polar or @chrispolarusa on Twitter =)