I use a VDO MC 1.0 computer on my Surly Cross Check to keep track of how far, how fast, and for how long I've been going. It's a pretty nice computer for the most part, it does the basics of speed, distance and time reasonably well, and adds an altimeter to track things like total climbing, % grade, current elevation, etc. It's worked well for me in the 2,500 or so miles I've been using it with the exception of two rides.
Since I've had it, I've done two 600k brevets with it. Both times, about 300 miles into the ride it spontaneously reset itself. Not a full reset, but all of the ride data went away and started back at zero. The first time it happened, I just assumed that it was either a loose connection that momentarily disconnected the battery, or maybe it was pilot error and I accidentally pushed the wrong buttons (quite possible after 300 miles). When it happened on my second 600k I got suspicious. It had never happened on any other rides and both times it happened about 300 miles into the ride. That's just too much coincidence to be... well, coincidence.
So today I finally got around to doing some googling to see if this is a known problem with this computer. Lo and behold, right there on page six of the owners manual it says, "Important: If the ride timer overflows 19:59:59 h, it is automatically reset to 00:00:00. Simultaneously, your average speed counter AVG SPEED is reset to zero. If your trip counter overflows 999.99 KM or M, it is automatically reset to 000.00 Simultaneously, your average speed counter AVG SPEED and your ride timer RIDE TIME are reset to zero." Note that I have the Instruction Manual at home, but had to use Google to find this information. And to rub it in, the manual repeats this information in Deutsch, Français, Italian, Español, and Nederlands.
Finding this in the instruction manual (or Manuel D'Installation Et D'Utilisation if you prefer) tells me that this is not a bug, but it's actually a feature of the product. Okay.
I mean, I realize that not a lot of VDO's target market is out there doing 20 hour rides, but still you'd think the failure point would be somewhere so far outside the norm that you wouldn't run into it unless you're really looking for it, right?
So since this information had me a bit annoyed, I posted this on Bike Forums in the Long Distance Cycling section to see if anyone there could recommend another computer that didn't have the feature. It turns out that this feature is not unique to the VDO MC 1.0. For example, I'm told the CicloMaster 4.3A only displays ride times up to 9:59:59. Another poster mentioned that he didn't know of any computers that would record more than 24 hours.
So, I guess I'm just going to live with this feature of the VDO MC 1.0. After all, it's not like knowing my average speed over an entire 600k is essential information. Still, I'm starting to notice an annoying trend in cycling products designed for the mass market. The product designers are apparently making the assumption that the users of their products don't actually do much cycling. I suppose they have a point. There are an awful lot of bicycles in this country that are stored in the basement next to the Nordic Trak and are used primarily for drying laundry.