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Zipp Cognition Hub Compatibility with Magnetless Speed Sensor

Former Member over 8 years ago

Just upgraded to Zipp 404 NSWs with a Cognition Hub and attached my magnetless speed sensor. Speed sensor (attached to my rear wheel and while on my indoor trainer) registered well below my actual speed - i.e., showing 1.8mph to 2.5mph no matter what gear I was in or how hard I pedaled. Changed the battery and had the same results - although occasionally I'd reattached the sensor to the hub and get a reading in the 6-8mph range. I could take the sensor off the wheel and "mock spin" it by hand and get readings in the 20-30mph range, but then reattach to the hub and again be less than 5mph! Started researching the issue and found a few obscure posts that claimed magnetic fields can interfere with the magnetless speed sensor.

Directly from the Zipp website: "The rear Cognition

hub with AxialClutch

technology reduces drag by disengaging the ratchet mechanism when coasting. It then uses magnets to re-engaged once the rider starts pedaling..." (emphasis mine).

Since I'm using the sensor on a bike trainer this winter and have to get the reading off the rear wheel, it'll be several months before I can get a front wheel reading off of it. Although, I put the sensor on the front, spun it by hand and was able to get readings between 10-12mph - which seemed fairly accurate. At this point, I think I found the problem... So, the purpose of this post is to see if anyone can confirm the magnetic field interference issue, and if so, to alert others using this wheelset of the issue.

0 aweatherall over 8 years ago

Yes it is very likely that the agent will interfere with it, see this https://support.garmin.com/faqSearch/en-US/faq/content/9NL91YJSJd3Tnyif9jRSy6

0 Former Member over 8 years ago

Atkins rue

Thanks for the reply and the link to the article! That link didn't come up in the searches I was doing, but glad to know Garmin is aware of the issue. I guess the old wheel will go back on the bike while mounted in the trainer.

-Cheers!

0 weaver07950 over 7 years ago

I have had the same problem with the Zipp 404 NSW wheels using the rear hub (cause we are on trainer). I would get reading like 1.0 mph when I was pedaling as high as 20mph. I noticed the hub outer surface diameter varies from larger on chain side to smaller on other side and the plane of the sensor was not parallel to the axle, and I wondered if that might be a problem. So I re-positioned it, raised up against the spokes on the low side so as to make the sensor plane parallel to axle, and this fixed the problem!!!

0 weaver07950 over 7 years ago

Follow up: The re-positioning fixes it sometimes. Best solution is to use a different rear wheel on trainer or use front wheel for speed when on the road.