The posts and reviews I’ve written about my experience using a Sigma Rox 9.0
have been very well received over the past year or so. (Check those posts out here for some background.) I noticed that Sigma has recently released the Sigma Rox 8.1 and the Sigma Rox 9.1–two new units in the Rox range. Since there seems to be some interest in these computers, and little discussion (at least in English,) I thought I’d take a quick look at the features of the new units and provide my thoughts.
Sigma Rox 9.1
Note that I don’t actually own one of the new units, and haven’t even handled one (test units appreciated!) but will evaluate them based on my experience with the Sigma Rox 9.0 and the feature set I have found on the web for the new units.
To start with, the Rox 9.1 and Rox 8.1 look very similar to the old 8.0 and 9.0. No major changes in form-factor or controls that I can tell. I assume the mounting hardware, cadence and speed transmitters, and heart rate strap are all the same, so not much to comment on there.
New Features:
Unlike Apple, Sigma decided to add new features to their new product! (I know, I know, low blow post-iPhone 4S announcement.) Here are some of the noteworthy upgrades, and my comments on each.
Power: You can’t put out a high-end cycling computer and be competitive in the current market without including power. Unfortunately, Sigma chose perhaps a poor approach to adding power; they didn’t make the Rox 9.1 ANT+ compatible. This means you can’t link the Rox 9.1 with your SRM
or PowerTap
, or multitude of other ‘open’ devices. Sigma didn’t even make it W.I.N.D. compatible like the Look Power Pedal, which talks to Polar head units
via the proprietary, and likely doomed-to-fail-because-of-it W.I.N.D. standard. (On a side-note, why don’t we all just move to Bluetooth and get along?!?) No, Sigma chose to go a similar route as the iBike
, calculating power from some magic formula, not from strain gauges or other ‘direct measurement’ approach. According to Sigma, this magic formula to calculate power takes into account:
Bike type and position, bike and rider weight, rider height, shoulder width, speed, incline and cadence.
Of course, these factors:
can be affected by external forces such as the ground conditions or wind.
it looks like some of this has been taken into account during the calculations, as Sigma claims that:
These factors are reduced during mountain ascents and considered in the calculation.
Great. However, without some way to know the wind speed, you are reducing an unknown by an unknown. And even if wind speed was measured, what about when drafting? What about on a gravel road? What about with a knobbier tire…? There are just too many factors to accurately take into account. These issues are why the iBike has never really caught on, despite having a much more attractive price-point than other power meters. It just simply doesn’t work as well.
Having said all of that, the real question is; just how accurate is the power number calculated by this magic formula? I’d love to see some head-to-head tests that show it is within 1 or 2% of an SRM or PowerTap, but even the iBike had trouble with that, despite measuring much more than the Sigma will (wind speed, etc.) Again, I’d love to be proven wrong here, as we need an inexpensive, relatively accurate power meter for the masses!
Expansion: Another new feature is the inclusion of “Expansion” as an on-screen option, and a value recorded in the logs. What the heck this means isn’t clear from the name (perhaps German speakers would understand the translation thought process a bit better?) Essentially, it appears to be a term for what we would call “gear inches” or “meters of development” – essentially, how far you travel in one pedal stroke. Interesting to know, but… how applicable this is in your on-the-bike riding, or post-ride analysis, I’m not sure. I suppose it would be good for new riders to show overlap between gears? I’m assuming it’s calculated by taking into account your current cadence and distance travelled. No magic there.
Ghost Race: Perhaps the neatest and most useful of all the new features is (in my opinion) what Sigma is calling “Ghost Race.’ It’s the same concept as Garmin’s “Virtual Partner” – where you can load in a previous workout on the same course and then ‘race’ your previous effort. This (aside from being fun) I can see as a great way to push yourself just that little bit more in a Time Trial or similar situation. I bet I could make good use of it in my 40km Project! :)
Existing Issues:
We all know new features are great, but did Sigma take care of the existing issues with the unit before adding new ‘bling’? Lets see! Here are some of the issues I commented on that bug me about the Sigma Rox 9.0. Have they been addressed in the 9.1?
Durability: If you recall, my 9.0 has issues with ‘scuffing’ and paint chipping. It’s hard to tell if the new units addresses this issue. I sure hope so; a scruffy looking computer on a nice shiny bike is not a good look, no matter how cool the computer is!
Battery Life: The Sigma website lists the battery life as one year. This matches my experience with the Rox 9.0, and leaves me … unimpressed. A rechargeable battery would be nice, but may bump up the price point.
Resetting Distance: Again, hard to say if this issue has been corrected. I suspect it is a software glitch to begin with, so probably independent of the unit itself.
Heart Rate Zones: There are still only three heart rate zones. It seems like such a trivial matter to add 5–why not? Pretty much every heart rate monitor I’ve ever seen has five zones…
Saving Cadence: It appears that the Rox 9.1 may save cadence to the log. Under “Data Center Functions,” the feature list shows “Graphic display of the cadence,” so it appears that the data may be saved to the logs. However, under the “New Memory Values” section, it lists only “Average power, maximum power, average expansion, average expansion uphill” as additions- no cadence. So the jury is out on this one. I hope it’s there!
Log Saving Interval: Still no 1-second saving option. Again, since this is user-selectable, why not? If I am going on a longer ride, or know I am low on memory, then I could set it to 5 or 10 seconds. But if I know I am going for a 2 hour ride, and will be downloading immediately after, why not give me an option to record every second? Silly.
Conclusion:
Without seeing and using one of these units (again, test units appreciated!) for at least a year, it’s really hard to say just how good it is. However, it appears that Sigma have added a couple of arguably less-than-useful new features (Power, Expansion) and one neat, but not groundbreaking one (Ghost Race) to their existing unit. With the competition that’s currently out there, I’m not sure the Sigma has a real value-equation working for it. Unless, of course, they’ve magically figured out the power calculation and the results are good, in which case this is a huge winner. Am I holding my breath on that? No. And I doubt you should either.
Having said all of that… the best thing to do is check it out yourself on the Sigma Rox website, and see what you think! If you can get a hold of a unit, give it a thorough test–I’d love to hear any comments from you below!
