coffeesnob

I have a specialized speed zone that adds about a 10th of a mile every 3/4 of a mile give or take. I am certain the set up is correct in all aspects. Are these things just that bad or what. My wife has a bontrager of the same type that is spot on. Any help is appreciated..

Iride01 

Never compare two or more devices. That will drive you nuts.

Probably the wheel calibration isn't set right. If you just entered something you got out of the book, well that's okay, but might not be what your tire is. You need to do a rollout and measure. Put a spot of white out or something on your tire that uses the wheel sensor and ride it for a few turns of the wheel and then measure the spots. Use that for figuring out what the circumference is and use that value. Note what your tire pressure is because if you are going to be picky enough not to be satisfied with the discrepancy you are currently seeing, then tire pressure will make a difference too.

No, not really. Just quite a few people expect too much. And it gets worse with bean-counters as they move to more expensive cyclometers with gps and mapping . They feel they paid good money for a recreational device and they want survey quality accuracy.


Oh... and you'd be surprised a the difference that you might see between two riders were one always swings wide on turns and the other stays close to the inside....... so don't expect others to match yours.

Seattle Forrest

Agree about the bed for a roll out. The same tire will come out to different sizes on different rims, even at the same pressure. The size printed on the tire isn't always accurate either, some are bigger than claimed, some smaller. Most people set this kind of computer up by looking up 25 mm in the booklet, as if all tires that say 25 mm are the same size in real life.