Anyone familiar with setting up the speed/cadence sensor for a Garmin 305? I think I've got the speed sensor up and running (the red light flashes on and off when I turn the pedals), but I can't seem to get the spoke magnet close enough to the sensor. Plus one of the spokes on my bike scrapes the sensor arm with each revolution. Any advice? Thanks.
I had the same problem. The spoke magnet would work fine with my 310xt, but the crankshaft sensor woudl never recognize, therefore, no cadence info. Its really annoying, and I had the same problem with my CatEye before the garmin. I eventually just took it off and will probably send it back to garmin and demand a refund.
If you have the same problem with two different brands of cadence/wheel sensors, I would suspect something else is going on other than defective units. To the OP, have you tried holding the spoke magnet in your hand and pinpointing where and how close the spoke magnet needs to be to the sensor unit? There's a groove on the speed sensor arm, but it's not always perfect, depending on the individual magnet. That will let you figure out how far to rotate the arm or move the entire unit front-to-back.
Also, the sensor arm can be oriented away from the bike frame or rotated down so it's tucked next to the chainstay. One position may work better than the other, both for clearance and for magnet pick-up. You can also mount the sensor so it's above or below the chainstay - on a road/tri bike, either way should work fine. (With the cadence sensor, don't just use a zip-tie. Your magnet should have some adhesive, or just use some glue/double-sided tape.)
Great advice. I'll tinker a bit more with the above in mind before throwing in the towel. Thank you!
My main problem is that all these cadence units are held on to the chainstay with 2 zip-ties and they can slide around fairly easily. If I play with it for 15 min before each ride I can usually get it to work, but it becomes more hassle than its really worth. I just wish there was more margin for error with the distance the sensors need to be from the main unit... oh well, can't win them all I suppose...
If it's the zip ties that are the problem, then just use a pair of pliers/vice grips to really crank them down. Putting a piece of rubber (like one of those bits that are for shimming the handlebar mount, or just a piece of a rubber band) in between the unit and the frame will make the unit stick better to the frame too.
I had similar problems getting it to work and actually took my bike into REI (where I got the sensor) and they showed the adjustment I had to make to get it to work.
A few things I learned from that...
1.) The cadence sensor magnet on the crank arm has to be EXTREMELY close to the Garmin cadence/speed sensor device on the frame - almost scraping it.
2.) The zip ties have to be VERY tight - I recommend you tighten them with pliers (pulling the ends tight) before you cut the excess off.
I actually take the sensor off for races, so I've done it a ton of times. I'll be out at the duathlon this week if you need help.
DCRainmaker has the most extensive reviews and I would say the resident expert on Garmin devices so you could also hit him up...