tomtomtom123

I was wondering if anyone uses a rear mounted speed and cadence sensor with bluetooth on their folding bike? Since the wheels are small, for example on a 20" bike, the pedal sits over, or slightly in front of the rear tire, so the distance between the magnet on the crank and the magnet on the spoke is pretty far. So many popular sensors are too short to reach the distance.

For example. the Cateye ISC-12 probably won't be long enough.



You could use models that use a set of 2 separate sensors, like the Wahoo magnetless. But I think some bike computers and smartphone apps have problems connecting to 2 of these devices at the same time. I've also read that these types of sensors give bad readings on bumpy surfaces. So magnetic sensors would be more accurate.



There are also some cheap Chinese sensors, attached by a cable. But the reviews indicate bluetooth connection problems.




I found this Japanese blog where the rider originally tried to get a Topeak Panobike sensor to work. But replaced it with a Topeak Duoband sensor. It seems to just be at the maximum reach. However, the rider is using the old magnet from the Panobike sensor, which gets pressed into the hex slot of the pedal spindle, which had to be taped on, or risked falling out. The magnet that comes with the Duoband sensor gets mounted further forward of the pedal with a zip-tie, which increases the distance that the sensor has to reach. I also use a shorter 165mm crank arm. And I have MKS quick release pedals, so I don't think I could stick the magnet at the pedal spindle.
https://blogs.yahoo.co.jp/lapinssblanc/38154090.html




I was also wondering about which bluetooth bike computer would work better, considering the limited sensor options for folding bikes. I've been eyeing the Cateye Padrone Smart plus, and the Topeak panocomp x. They each have slight differences in functions, and a bigger difference in battery life. But each computer is locked into using their own smartphone app if you want to use mirrored mode, and link the sensors, smartphone and bike computer together. I couldn't find reviews for the apps. But I wonder how they compare in terms of smartphone battery consumption and ease of use and reconnections, especially with long bicycle tours, with multiple stop-and-go throughout the day, where you might walk away to go into a supermarket which would break the bluetooth connection.

linberl

I have a bike friday pakit and you can't use a magnetic system on the rear as there's no where to put it. I've been quite thrilled with the combined performance of my Cat Eye Stealth Evo+ and my Wahoo Wireless Cadence sensor which does not require a magnet. https://www.wahoofitness.com/devices...cadence-sensor I personally am okay with the gps speed on the Cat Eye but if you want total accuracy on speed then Wahoo makes a magnet-less speed sensor as well. I'm a lot more focused on cadence than speed so the slight gps lags don't bother me. I've not found any reading errors with the Wahoo cadence sensor, regardless of bumps.

Trocadile

I use the cheap CooSpo device on my Xootr Swift, connecting by bluetooth to my iPhone and getting reliable speed and cadence readings. No problems so far, but I mostly use it on a dumb trainer with Rouvy.

fietsbob

Maybe Write a GPS App & a have the Camera looking at your feet , counting the cadence
Universal, you could use it on any bike .then..

tomtomtom123

I decided to use the Coospo (around $25) because I couldn't find an alternative that might fit on my bike. I had some trouble mounting it with the zip ties, because my Dahon Vigor has a very long welded plate where the kickstand attaches. But in the end, it seems to be stable. There was really only one position on the chainstay where I could mount the cadence sensor. One zip tie goes into the little punchout hole that forms a tab that the kickstand can press against to keep it from rotating. I twisted the kickstand the other side so that it pressed against the opposite tab, to open up the hole that I needed. I think it's ok, but if for some reason the kickstand rotates under heavy load, it would snap the zip tie. The second zip tie had to go all the way around the weld. I also have thick tires, and there is only maybe 3mm of clearance between the zip tie and the tire. Seems to be ok, but if a large piece of debris gets picked up between the tire and the mudguard, it could possibly snap the zip tie.

Here are some photos and dimensions. @Trocadile Where did you line up the magnets on the sensors? I thought the indentation lines on the plastic housing at the very far ends were an indicator for alignment, but I wasn't sure. The maximum distance between those lines are 120mm. My cadence magnet was 20mm forward of my MSK quick release, and the spoke magnet was 20mm away from the spoke nipple. So if you have a shorter sensor, you could possibly get the magnets as close as 120 - 20 - 20 = 80mm. But the closer the spoke magnet gets to the nipple, the greater the distance to the sensor. I had the gaps between the magnets and sensors about 12-14mm. I also could not move the cadence magnet closer to the MKS quick release, because then I'd have to move the cadence sensor rearward, but it's blocked by my wide mudguards. It may have been possible if I trimmed off a little bit of the rubber and plastic housing on the cadence sensor, but that would be too much work.

One complaint on Amazon is that the zip ties break before you can tighten them down, and some people ran out of zip tiles before they could complete the installation. I broke 3 zip tiles, but there were 4 spares included. I connected the sensors to my phone with Bluetooth and it seems to connect and receive data. When the sensors shut off, and I spin the crank to turn them back on, the apps I was running didn't reconnect until I pressed some buttons in the app, but that was probably because it was not recording a ride and actively searching for a sensor. I haven't make a test ride yet, but I'll tomorrow. It seemed to take 3 seconds between the start of scanning to the start of receiving data, probably caused by the time needed to do the bluetooth handshake. I assume that ANT+ would be faster, since no handshake is required, but my phone is not equip with ANT+. The manual said to flip the button battery so that the positive side was outward to start power, but the battery was already on the correct side. I measured the voltage of the battery just in case, and it was 3.2V, which is rated at 3.0V. The manual claims 500 hours.





If it didn't work, I would have tried these really cheap Magene 200/210 magnetless sensors. I assume the components are identical to all the other big brand names, but the software and implementation may be different. They cost around $12 from Aliexpress. You'll get false readings on bumpy surfaces though. But some blogs write that it has trouble activating under 5 kph. Supposedly the 210 is a newer version that is more sensitive, according the advertisement. But the seller pages aren't very clear if you are getting the 200 or 210, and the only indication is on the battery cover, which could be switched.
https://www.aliexpress.com/item/MAGENE-gemini-210-Speed-Sensor-cadence-ant-Bluetooth-for-Strava-garmin-bryton-bike-bicycle-computer/32912954356.html
https://www.aliexpress.com/item/Moun...805438187.html
https://www.aliexpress.com/item/MAGE...850760736.html

I prefer the sensors with magnets because they're more accurate. And they won't switch on accidentally, like if you were on a bus or train.

Trocadile

I lined up the magnets with the notches. Using my picture as a reference, the cadence magnet is on the far left and the speed magnet on the far right. I tried different positions and the notches were clearly the most responsive placements. The supplied zip ties are terrible. So many broke while installing it, I decided to use different ones (I have a lot lying around). I wouldn't trust the ones that came with it.

tomtomtom123

The zip tie that went through the kickstand plate broke after 20 minutes of riding. So I'll replace it. The ones I have are even thinner though, but I guess it depends how brittle the material is compared to the supplied zip ties.

The CooSpo sensor seems to be working ok. Speed looked accurate. Cadence had a few high readings, maybe it's when I was standing on the pedals horizontally causing the magnet to pass the sensor rapidly. Cadence also took 5 seconds to drop to zero when I stopped pedaling, but I think that's from the way the formula is calculating in the app I was using.

One app had trouble maintaining a bluetooth connection. Another app seemed to work fine, and even picked up the sensors again pretty fast after they switched off from a rest stop. I thought you'd be able to connect 2 apps in the same phone to the sensor via bluetooth, but maybe there is a conflict between the 2 apps.