Holux GR-260 is a GPS bike computer. Unfortunately included software lack some features. Most notably it does not export GPX file with Garmin extensions - Heart Rate an Cadence measurements. I've wrote my software for this purpose.
Protocol was partly sniffed on USB, but quickly was discovered in small utility that is here:
Logger is a bit tricky, You need to switch baudrate to 921600 just to download data commands execute properly.
My software lacks checksum checking and retransmissions and does not work properly on slow computers which have problem with grabbing almost 1Mbit stream from logger.
I give You it only for educational purposes.
Program autodetects serial port - press DETECT PORT button. After "OK Got it" press DOWNLOAD TRACKS. It will create one file for each track. Do not delete files from working directory, it checks for them and does not download them on next use.