PDA

View Full Version : Bike computer issues x 2



JustinW
02-12-2011, 04:51 PM
Two questions re: bike computers...

- Just installed a wired Cateye computer on a new bike. My existing bike has a wireless computer. Both of those read consistently higher in terms of speed and mileage accomplished compared to GPS readings done at the same time. I've double checked the setups to make sure wheel sizes, etc, are all correct. Why the discrepancy? Are bike computer companies conspiring to make purchasers feel better by inflating data?

- On my new (well, new to me) bike the rear wheel was evenly balanced. Now with the addition of the little magnet used for the speed sensor, the balance is off. This is not really noticeable (so far) except if I spin the wheel really quickly; one ride so far has not detected any issues. Any thoughts on ways to negate the imbalance, or is this something that, in real use, I typically won't feel?

TIA

PrintError
02-12-2011, 05:33 PM
If the 0.00001 grams of the magnet is off-balancing your wheel, there may be a bigger problem with it. I've got the little magnet on my front wheel, and it doesn't send me tumbling when I'm over 30-35 mph, so I'm fairly certain it's a total non-issue.

As far as the calibration issue goes, honestly the computers are guessing to the best of their abilities based on outer diameter assuming a standard inflation rate. GPS's are highly sophisticated systems based on satellites. My navigation GPS and the speedos in my cars don't always get along. Mechanical vs. satellite. Really, it comes down to how accurate does it really need to be? I've checked my bikeputer vs. MapMyRide vs. a Garmin mounted on the bars. Honestly they're so similar it doesn't matter that much to me.

CCrew
02-12-2011, 07:21 PM
Put the magnet on the 180 opposite of the valve stem. Since the valve stem will usually find "bottom" with the bike on a stand it'll slightly offset it somewhat.

You'll never notice it and it's no issue at all really, but it soothes the OCD in us :)

PrintError
02-12-2011, 10:02 PM
Put the magnet on the 180 opposite of the valve stem. Since the valve stem will usually find "bottom" with the bike on a stand it'll slightly offset it somewhat.

You'll never notice it and it's no issue at all really, but it soothes the OCD in us :)

Funny you say that. I always align mine with the spoke nearest to the valve stem so it's easier to find.