Ephemerica

Hopefully we will be adding gear reviews here from time to time:

VDO MC1.0 Bike Computer
Garmin Edge 205 GPS Bike Computer

VDO MC1.0 Bike Computer
Originally Posted 9 Dec 2007
Last Revised 18 Dec 2007

After our Garmin bike computer was lost in our robbery in Nicaragua (the thieves destroyed it trying to remove it from the bike mount), we decided to look for a replacement. Without the laptop, having the GPS wasn’t as interesting to me because we would have no way to record our route information, which was the primary reason we purchased the GPS in the first place. But we knew that we would have a lot of climbing ahead of us in the Andes, so we were interested in getting a computer that at least had an altimeter. I did a little searching around, and found some decent reviews of the VDO MC1.0, and found it for a decent price at bikesomewhere.com (under US$100). I ordered one and had it shipped to Cindy’s dad, who then brought it down to us when he came to visit us in Panama City. I’ll first discuss the basics of the unit, and then how its performance compares to the more expensive Garmin GPS unit.

First of all, because there seems to be some confusion out there, this unit comes in both wired and wireless versions—the wireless version is designated MC1.0+ and costs an extra US$30. The magnet on the wired version is front mounted, and the only problem I can think of with this would be if you planned to use the computer on a bike while using a rear-mounted trainer (i.e. the computer will only record data when the front wheel is spinning). Personally, I decided that the extra cost, combined with the pain-in-the-butt factor of needing to deal with batteries for the wireless transmitter made the wired version the clear choice for me.

The mount itself has its plusses and minuses. On the plus side, the mount can be rotated 90 degrees, allowing the computer to be installed either on the handlebar or the stem. On the minus side is how you attach the mount—via two zipties. This in and of itself wouldn’t be so bad, but it is compounded by how you attach the computer to the mount. Rather than sliding the computer on and off in a linear fashion, it requires a circular twist of quite a bit of torque, placing a large amount of stress on the zipties. The zipties that come with the computer are not thin cheapies; however, it seems unlikely that they will be able to take the twisting indefinitely. I guess since VDO decided that twisting was a better way to attach the computer, it’s better that the parts most likely to fail (the zipties) are easily replaceable…but why build it that way in the first place?

The display is crowded, but the LCD is big enough that all the numbers are clear to read. Permanently displayed are average speed, altitude, slope and temperature (used to help calculate altitude). The bottom of the unit displays various bits of data. The unit has three buttons; one on each side and one on the front. Each button has been assigned a subset of the functions of the computer, and pressing one of the buttons cycles through those functions. The left button has most of the traditional bike functions (trip distance, ride time, average speed, stop watch, maximum speed). The right button displays the odometer readings, clock, and a function called “navigator”, which works kind of like a separate trip odometer (i.e., resetting the navigator during the ride doesn’t reset the trip distance). The computer remembers two wheelsizes (if you want to use the computer between MTB and road bike, for example) and has separate odometers for each of them, plus a combined total odometer. The front button cycles through all the altitude data, trip altitude (i.e., meters climbed), max trip altitude, average % climb, max % climb, total altitude, and also records your top elevation overall. It took me a few weeks of using the computer before I remembered which functions went with which buttons. Almost all of the “hidden” operations (e.g., resetting the trip information, setting wheelsize, setting altitude) are reached by holding one or two of the three buttons for 3 seconds. However, some of these operations only work when the computer is displaying certain information. For example, to reset the navigator, you must have the navigator in the display (the navigator is NOT reset when you reset the trip information). I can’t say that this is needlessly complicated, although I’m glad I held onto the manual, because I have to look any time I want to adjust the settings of the computer. The display of the unit shuts down, displaying only the current time after 5 min of inactivity. This is much nicer than some of the other units I’ve used—namely Cateyes—which seem to stay on for about 30 min after they stop receiving input. Whether or not this actually has any effect to lengthen battery life, we’ll have to see.

On to the altimeter. The altimeter needs to be set initially when using the unit, and then calibrated periodically thereafter. There are two ways to calibrate the altimeter. The first uses a “home altitude” as a reference, and is really only useful when biking around your home, although that probably applies to most people. You can enter your known home altitude, which is saved by the computer, and then with the press of a few buttons, set the unit to that altitude (preferrably when you are at your home). The other way to calibrate the unit is to manually enter the altitude of your current location. How I’ve been doing it on the road is to use Google Earth to find the altitude of a location that is easy to recognize from the sky—a main plaza, for example. Then I take the unit to that location, and adjust the altitude reading accordingly. It seems to work best if you can calibrate the unit at an elevation close to where you plan to use it. For example, when we had calibrated the unit in Bogota (2200 m), we found that it wasn’t horribly accurate at sea level.

Now to compare to the Garmin unit. My main complaints with the altimeter on the Garmin unit were 1) we saw huge fluctuations in altitude when satellite coverage was sparse, or we didn’t have a clear shot at the sky (e.g., when riding in deep canyons), and 2) that the slope information was largely useless due to inaccurasy. The first complaint is for the most part taken care of with the VDO unit. The barometer is very stable from moment to moment while riding. However, barometers have their own quirks to them, namely diurnal variation in atmospheric pressure. I usually record the altitude when we finish our rides in the afternoon, and take another reading the next morning before we leave. These two readings, from the exact same location, vary by probably 50 m on average, and can differ by up to 100 m. So the obvious question is, when is the best time to calibrate the unit? Well, judging by the graph of the averaged air pressure data from the Wikipedia entry, air pressure looks to be most stable around the middle of the day…although I can’t say I’ve used that rule much. For our purposes, exact altitude is less important than relative altitude, so as long as the reading is ballpark to known values, I don’t bother fussing with the adjustment. As I said previously in the review of the Garmin unit, I can only assume that the Edge 305—the more advanced unit that combines satellite data with a barometer—combines the best of both methods to come up with the most accurate measurements.

My second complaint about the slope is also somewhat improved in the VDO unit. The manual states that the slope display is an average of 12 seconds worth of data. For the most part, the data seems to be reasonably accurate, and unlike the Garmin, also displays downhill slopes accurately. However, I have been surprised to find some erroneous values that are recorded for the “max slope” at the end of rides, with the most outrageous being 98%! I think these erroneous readings happen during transitions between starts and stops. When the computer comes back on after having turned itself off, sometimes there are some initial fluctuations in the altimeter readings, and I think these may lead to temporarily out-of-whack slope values. I’m not sure why this might be, since the computer supposedly requires 12 seconds of data to calculate a slope. If I recall correctly, the Garmin slope display was blank until it had accumulated enough data to give an accurate reading; the VDO unit would be better to do the same. However, the average slope readings seem to be pretty normal.

Overall, I’m very happy with the VDO. Additional plusses that it has over the Garmin unit are not having to charge the computer after every ride (huge!), and the fact that the VDO acts as a pocket altimeter even when it’s not on the bike, which is nice for checking altitude when we are on buses or traveling down the world’s most dangerous road on somebody else’s bikes. Technically, you could do those things with the Garmin, but the constant need to have clear access to the sky meant that it was highly impractical. The things I really miss the most about the Garmin (that the VDO lacks) are the ability to record ride data to computer and the electronic compass (especially since our real compass was also stolen from us). Another feature that would benefit the VDO is recording total descent as well as ascent—something the Garmin does, and it looks like the MC1.0’s big brother the Z1 (not yet available) does it as well. 

UPDATE: I recently broke the wire from the mount to the wheel sensor. It was a difficult surgery, but I managed to reconnect the two broken ends, and I think it will continue to function. Turns out that without sufficient instructions, my first instinct was to wrap the extra cable around the headset/head tube rather than around the front brake cable. DON’T DO THIS! My bike fell over and the extra rotation of the front wheel broke the cable where I had ziptied it to the fork. The installation instructions should be changed to reflect this. Kudos go to companies like Cateye who not only tell you this, but give you a plastic coil to wrap around the computer and brake cables to keep them together.

 

Garmin Edge 205 GPS Bike Computer
Originally posted 25 May 2007
Last revised 27 May 2007 Prime hd
The Garmin Edge 205 bike computer was one of my splurge purchases before we left. At that point, we had decided to take the laptop along, so my main goal was to use the GPS unit (along with the laptop) to record as much information about our route as possible, in addition to all the traditional things one uses a bike computer for (speed, distance, time, etc.). This review will not be totally comprehensive; I’ll mostly discuss how the unit has functioned in regard to how we’ve been using it, and how we are retrieving/recording the data.

First, the basics of the unit. The unit itself is slightly bigger than a normal bike computer (about the size of a cell phone), but not as big as some other GPS units I’ve seen. The LCD screen follows the same pattern, which brings me to my first caution regarding this unit. I agree with what others have written about the unit—this unit is NOT for navigational purposes. It is first and foremost an exercise tool for monitoring and recording bike workouts. It has some navigational features, most of which I haven’t used. But this unit is not something you want to rely on to help you if you get lost. In my opinion, the most useful navigational feature of the unit is the built-in compass (which automatically adjusts for magnetic declination).

Back to the LCD screen: there are two “virtual” bike computer screens that can each be pre-set to view up to 8 of over 20 attributes that the computer will measure. Users can then toggle between the two bike computer screens to view different data, or for couples that are sharing the computer, each can have their own personalized bike computer screen. I have one screen set for “normal” biking, that has speed, elapsed time, distance, time of day, and direction of travel, and a screen for “climbing” which has average speed, GPS accuracy, elevation, grade, and sunrise/sunset times. Let’s go over some of these items.

The unit is completely wireless; thus all parameters such as speed and distance are determined by movement as detected from the satellites. Cindy and I have compared speed and distance data between our two computers (hers of the traditional wheel magnet variety), and they are reasonably similar. My biggest complaint is with the elevation/grade data. This unit is distinguished from its more expensive colleague, the Edge 305, by (among other things) its method of determining altitude; the Edge 305 uses a barometric altimeter in addition to GPS data to determine altitude, while the 205 only uses GPS data. In our experience, we have seen major fluctuations in reported altitude when the satellite coverage gets sparse. If you look at the elevation profile graph here, you can see spikes where the elevation reading varies up to 200 m in a matter of minutes (you’d have to be riding in an elevator to get that for real). I haven’t used the 305, but I would hope that the barometric altimeter helps the unit stay more stable when the satellites are not around. However, most of the time the altitude readings are stable and reasonably accurate, as judged by the elevation information we have in our guidebooks.

The winner of the “most useless” category is the display of grade. These readings have been so inconsistent as to be worthless in telling us how steep the hills are. We’ve gone up hills that are supposedly up to 20% in grade, but have never gone down a hill that was more than a -5% grade…seems unlikely. The second most useless data is calories burned. I realize that the best they can do is make an estimate, and they make an estimate based on the height, weight, and age of the biker, and the weight of the bike. However, the one thing they don’t take into account is whether or not the biker is going uphill or downhill. The determination of your effort is based purely on your average speed; the higher the speed, the more calories you burned. So a 5 hr day at 8 km/h riding uphill all day burns the same calories as a 2.5 hr day cruising the flats at 16 km/h? The computer has this information available, so I’m not sure exactly why it isn’t factored in. I would hope that the 305, which can monitor heart rate, has a calorie calculator that takes effort into account. The “most useful” category goes to sunrise/sunset times. When daylight begins and ends are clearly important to us, and so having that information brought to us by satellite daily is indispensible.

So, we’ve just recorded a day’s ride, now what do we do? Well, first of all, we use the program LoadMyTracks to download the ride in KML format. The KML files are readable by GoogleEarth, which will allow you to do all sorts of fun stuff, like zoom in and do flybys along our route. Then we dowload the data again into Garmin’s Training Center (GTC) software (thankfully a Mac version was released not too long after we hit the road). GTC allows us to view summaries of our ride in terms of distance, time, avg/max speed, and also view elevation profiles. For those of you doing more structured exercise, there is also the ability to view the day’s ride by individual laps. We’ve been posting the KML files and elevation profiles on our GPS page.

Time for a listing of my beefs with the GTC software. First in the “statistics” section, it is not possible to customize the fields displayed there. For example, “avg heart rate” is one of the displayed categories, but the 205 doesn’t record heart rate data (requires the 305), so ideally I would be able to remove this category from the display to save space. My other complaint is that since the graphing capacity of GTC is limited, it would be nice if you could export the data in an Excel-compatible format for graphing in other programs. Currently, the data can only be exported in TCX format. However, overall the software is stable and does what it’s supposed to do.

I wanted to talk briefly about battery life. The unit can be charged via a USB 2.0 port, so we’ve been charging the unit from the iBook, which is great because it means we don’t have to carry the bulky adapter (included) on our trip. According to Garmin, the battery has an approximate life of 12 hours on a single charge. In our usage, it seems as though the battery life is much less than this. Admittedly, I have yet to fully drain the battery, but the battery LCD display has three bars, and after 7 hours of recording, the display usually shows one bar remaining (not sure whether the there is energy left if the unit is at zero bars). I have taken to being very conservative with the unit, turning it off if we are ever resting for more than a minute or two, and this seems to have helped extend the battery life.

Overall, however, we are very happy with the unit. I couldn’t bring myself to spend the extra $150 on the Edge 305 (seeing as how I already have a heart rate monitor with data recorder), but I might consider upgrading after we return.