> With most GPSrs, they'll allow you to get a good avg of 1-2' of accuracy if the GPSr sits in place for 15 minutes or so. Then you can get a good solid reading for that 1 km distance, hop on the bike and ride from one painted line on the ground to the next and you'll know how close your cyclometer is. <

Sure wish I had a GPS! But hard to justify since my use would be rather limited - mostly just get a few really accurate readings as you describe. Once that was done, I wouldn't have a lot of use for it. Similarly, I'd like to have some serious altitude checks. I think the maps would likely be more prone to error on this than on distance measurements. Likewise, I think the GPS units have a wider margin of error for this, but again, by averaging multiple times, I could get a much better feel for how close my topo map software is. But once I've checked some enough, I wouldn't need it anymore.

Thanks for the info.