A new bike computer: A review

With my morning rides while the kids are sleeping, I have rapidly determined that what I need is not only a way to tell time, but also a way to see if I am getting the mileage that I am shooting for in a limited window of time in the mornings.  I had spoken with a friend who rode STP a few years back and she suggested I guy something like what you see pictured to the side here.

I headed to REI on Saturday with the kids and decided to pick this one up.  At $20 it seemed like a great deal and was going to do everything that I needed to do.  I have previously owned a bike computer, but sadly it was of the "Hot Wheels" variety and was evidently so popular, I can't even find a photo of it on a image search.  However, after I opened the box to the Sigma BC 5.12, I saw that the mechanics were basically the same.  It came with two rubber bands for strapping the computer itself onto the handlebar (or you could switch out the screws to mount it to the stem, which I did) and another for mounting the wired sensor on the inside of your fork.  A magnet is attached to your spoke with a silvered sleeve to hold it into place as it helps monitor your speed/mileage.  This process was done in fairly short order with only a tiny screwdriver being used to change the mounting orientation for the computer itself.

The computer comes installed with a single button battery that is easily changed out, should the need arise, and the real beauty of this computer-and what attracted me to it other than price, was the single button on the face of the computer.  No up or down or menu keys.  You can easily press this with your gloves on while riding to find out any of the information you need from your ride while you are in it.  It locks into place with a simple twist on the mount.and the large numbers are easily readable.

Now, for someone that does not set up these things regularly, I must say it was beyond frustrating setting this thing up.  There is a single slightly recessed button on the back that you use for setting the clock/wheel size/auto scan function (a feature that will cycle through all of your available data while on the road-speed, trip distance, total distance and time).  Anyone that has set up a clock on any piece of electronics in the last five years should have no problem accomplishing this function and if you do have issues, there is a very large instruction manual that comes with step by step instructions in various languages on how to accomplish this.  The real problem comes when you are trying to set your wheel size.

Not only do the number of button presses seem arbitrary and not intuitive on any level, but how big your wheels are supposed to be and how you measure this is shown in two cryptic photos that show two different methods for determining the size with conversions for going from inches to mm's, I think.  This is the single most frustrating aspect of setting up this computer as the need to have this measurement precise is integral to getting good data from your cycling computer (and in my case, knowing that I have the right amount of mileage before I head back home).  For statistic fanatics, the wrong number in the wrong place means your data is all off.  The directions for this process are printed so small (7 point font, probably smaller) that I had to have my son read it to me, and even then-they were not particularly clear.  I even pulled out my copy of Zinn and the art of Road Bike Maintenance for some guidance, which helped, but when I had the required data, the reference chart on the instruction sheet was less than helpful in every way. 

The first day I took this computer out for a stroll my mileage was off by 4 miles at the end of the ride (4 more miles tracked than ridden) and this morning, it was off by .6 under what was actually ridden.  I will endeavor to tweak this again tonight, but the prospects of getting meaningful data from this unit seem slim.  Sigma does have installation instruction videos that are helpful, but nothing to help set the computer up with these measurements.  In short, if you can't figure this out exactly, you end up with a $20 dollar digital clock with no back light.

A final complaint is that this also has no real off function to conserve battery life.  Although the LCD display is not back lit, and probably will not suck much from the battery, the only offering that this unit offers is a standby mode after 15 minutes (a fact I had to find out on the FAQ of Sigma's website).  Be prepared, this thing is always on.

Because I am stubborn, I will not be taking this back as I can't imagine how I can be beat so easily by this little device, but I don't know that I would recommend this unit to anyone but someone who has spent years working with them.