Garmin offers a handlebar mount. The information it collects coupled with ability to download info to my PC would cause me to give up my cycle computer completely if my GPS had cadence.
The only other drawback is Max. Speed is iffy, I hit 51.3 MPH while walking to get a cup of coffee Saturday morning, but I don't log Max. Speed anyway.
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2003 Iceman Challenge - 2:34:55 - 897 / 2,000*
2002 Iceman Challenge - 2:39:23 - 1093 / 2,186
2000 Iceman Challenge - 2:49:18 - 1516 / 2,153
*estimated