I just got a roller trainer specially designed for unicycles. And I want to add a cadence or speed sensor to my unicycle. I wanted to buy a Garmin sensor, but I found the highest-suggested cadence is just 180 RPM. From the video, it seems my highest is about 280~320RPM. I’m afraid it might not be accurate at such high cadence. I heard a sensor with a magnet is more accurate. Does anyone have experience with it?
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The choice of 180 RPM being the top end appears to be a choice of the manufacturer and not a limitation of accelerometer-based cadence sensors per se. Most of the manufacturers figure that “most people” don’t ride faster than 180 RPM, so they design around that. Usually what they’re balancing is how much vibration noise they can reject (picking a low top-end RPM) vs getting enough samples of the rotating accelerometer to get an accurate estimate of the RPM.
You will probably have to use a pedal based power/cadence system to get readings near 200 RPM. Garmin Rally and Wahoo PowrLink Zero (and others) can go this high. Most (all?) of them are clipless, so you may either need clipless cleats or adapters for flat shoes. I do not recommend using this riding around, but on a roller trainer, you might be ok.
Also, neat trainer setup! Thanks for showing us.
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Thank you for the explanation. It seems that pedal-based systems are quite expensive. I think I’ll start with the Garmin speed sensor to see if it works for me. The speed and cadence sensors are similar, but according to Garmin, the speed sensor has a limit of 100 km/h, which corresponds to a much higher RPM than 180. Even if it’s not suitable for my unicycle on a roller, I can still use it for outdoor riding.
I’m using the Garmin cadence and speed sensor.
Unfortunately I haven’t pushed the cadence sensor past 160rpm yet. I’m working on speed at the moment so 180rpm is a matter of time and would be interesting to see what happens. I didn’t spot the 180rpm limit when I bought them and am a bit disappointed that this might be a limit.
With the speed sensor you will need a rubber strip under it to fit it on a thinner unicycle hub as the rubber band for it is a bit too long. I haven’t found a way to view the RPM data in Garmin Connect. Maybe with a different app you could configure it differently as the raw data has to exist.
All in all they seem to be good sensors that connect quickly to my watch when starting an exercise and deliver more reasonable results than GPS speed tracking alone.
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Thanks. I think 180 RPM is probably enough for me on road rides, especially on larger wheels. However, it seems easier to pedal fast on a rolling trainer, and I want to see how I could progress on it. Anyway, I’ll try the Garmin sensors first to see how they work.
I misunderstood the situation. I asked the AI to analyze the video to determine the highest RPM, and it reported an exaggerated number. After reviewing it myself, I believe the maximum is likely only about 3 to 3.5 turns per second, which translates to approximately 180 to 210 RPM. For this, I guess the Garmin sensors might still be able to handle.
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Also, for speed sensor mode, if it seems to be able to handle the higher RPM of a bicycle hub, you could figure out the effective RPM with a bit of algebra: 60 * speed / circumference.
I just got the Garmin sensors. I put both the speed and cadence sensors on and gave them a 5-min test. Though the maximum is exactly 180, which is the same as the officially announced maximum value to be measured. I’m not sure if it is accurate, but the maximum RPM seems to match the maximum speed.
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This time, I tested with only the speed sensor, and the max was 23km/h, which translates to 195 RPM. I don’t think I’m faster than yesterday, so I guess the cadence sensor has a 180-RPM limit, as officially announced. Though the speed sensor might also be affected by the vibration of high-speed pedaling on a unicycle, I think using it alone without a cadence sensor might be more accurate for monitoring high RPM values.
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Key takeaway: Don’t trust AI when it comes to unicycles. 
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Key takeaway: Don’t trust AI
Fixed. No need to thank me 
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I was hesitant. It’s a unicycle forum, after all, and I didn’t wanna go off-topic …'cause, you know, I never go off-topic! 
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I use Wahoo cadence and speed sensors paired to both my Garmin GPS. No issues with higher cadence, I usually ride between 90 and 150 rpm but have when younger gone over 200. However, it will not work below about 50 to 60 rpm just shows 0. Mine is attached to my riding shoes so works on every unicycle I use (or bike, if I were to ride one). Very reliable.
I only need the speed sensor for the GPS speed display to work at lower speeds, less than about 15kph. Without the speed sensor the Garmin’s speed display is inconsistent, but does not effect distance.
BTW, it’s really dumb that I have to have a speed sensor on the wheel and a cadence sensor on my shoe. They both send the same data! If the GPS knew about 1 to 1 fixed gearing I would not need both …
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I guess the reasoning behind this is that, on a b!ke, they don’t know what gear you are in (or at least can’t guarantee that they know it, since most people cant afford AXS or Di2 drivetrains). Thus for b!kes, you likely need two of them simply because of gears.
For a unicycle, you really only need one. But we haven’t flexed our collective muscle against them to have them make “unicycle mode” for the sensors.
Hmm! Mr. Schlumpf disagrees with you 
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Doh! I forgot! I even forgot about Huni Rex and Penguin unicycles!
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