noglider 

I bought the two-pack from Amazon for Xoss speed/cadence sensors for only $39. Each sensor can act as a speed sensor or cadence sensor. I'm only mildly curious about cadence, so after testing it for that, I will set up the two as speed sensors on separate bikes.

To switch between modes, you just remove the battery and replace it. The color of the light on the unit indicates the mode.

To pair it to my phone, it says not to use the bluetooth menu on the phone but to pull it in with the app. I had no trouble finding it with the ridewithgps app.

Installation involves tethering the sensor to the hub shell in the center. It spins with the hub. There is no way to calibrate it to the wheel's circumference. From that, I infer that it integrates with GPS data to calculate the wheel's circumference. That's pretty amazing. I imagine it could give more accurate and up-to-date information about my speed. I haven't tried it on the road yet. When I spun the wheel in my hand, the app didn't detect speed because, I presume, the GPS didn't detect me moving with respect to the ground.

canklecat

Yeah, I have a XOSS speed/cadence earth induction sensor too. It works fine in both modes.

But I mostly use it for cadence. In actual practice over many rides using both my bike computer and phone apps, comparing GPS, Bluetooth and ANT+ speed sensors, I rarely see significant differences. The exception is when the GPS signal is sketchy due to atmospheric conditions, etc. Or if I forget to calibrate my phone via the Google Maps compass calibration trick. Usually I can tell the phone needs to be calibrated when the GPS route trace for my rides and runs is ragged.

Bluetooth devices are finicky. Sometimes they pair better with the app when I don't pair them with the phone first. Other times I have to reboot the phone to get the devices recognized. And some are more reliable than others. My Skullcandy earbuds are the most reliable at pairing quickly. My Wahoo Tickr and XOSS speed/cadence sensors sometimes take a few tries to pair reliably.

I suspect the problem is interference from my own wifi router, the neighbor's devices, etc. I had fewer problems pairing Bluetooth devices in the living room after moving the wifi router to the bedroom. Since I usually set up for bike rides and runs in the living room, it's easier that way.

If I'm recalling correctly, wheel diameter is set in the app that uses the earth induction sensor mounted on the hub. That's how the XOSS app works for my XOSS G+ computer. I think I've done the same thing in the Wahoo Fitness app. But this presumes I'm always riding my road bike with 700x25 tires, rather than my hybrid with 700x32 or larger tires, or my other road bike with 700x23 tires.

Reminds me, I've been intending to remount my old wired bike computer and sensor to compare speed data.

Tourist in MSN

I get the most accurate speed and distance measurement from my wired computer, it counts every revolution and not any extras. My wireless computer is less accurate, that sensor appears to send a packet of info every few seconds and for some reason that does not quite get it spot on. That said one of my computers for speed rounds up to the next half mph, the other I am not sure if it rounds off or rounds up but that also reads in half mph increments, thus speed is less precise than my GPS that reads speed in tenths, but my GPS is less accurate, if I do the same exact route several times the GPS will not provide exactly the same distance each time.

njkayaker

All sensors work that way and have for many years. The head unit (the thing with the display) was always the part that knew the circumference.

Garmin have had the ability to use GPS to determine wheel circumference for years. You can also manually enter it.


Wheel sensors detect accurate speed changes more quickly than GPS. (This is related to the relatively slow speed of bicycles and the sampling rate of the GPS.) Speed sensors are very accurate for distance and speed IF the circumference is correct.

This is an issue. Maybe, it has no circumference value?

One reason to use a wheel sensor is to measure wheel speed indoors and on a stationary bike.

daoswald

I use a similar aftermarket sensor pair on my 2nd bike (I have the more expensive Garmin sensors on my primary bike). The aftermarket sensors I have work just as you've described; ANT+ and Bluetooth, and removing and replacing the battery switches between cadence and speed mode. The speed sensor, like all I've seen in recent years, wraps around the hub of one of the wheels. Front wheel on my bikes, but if I used a trainer I would put the sensors on the rear wheels.

With my Garmin devices (Garmin Edge 1030 Plus, and previously a Garmin Edge 820), the wheel size auto-calibrated after riding about a mile. The GPS also allows for a manual calibration mode. I think calibration is something that must be native to the device your sensor is connecting to. So in your case, I think the app in your phone would need to support calibration (auto or otherwise).

You may prefer just riding with a phone. But if you had $200 to spend, the Garmin Edge 130 Plus is small, convenient, and pairs nicely with sensors. It doesn't provide real mapping and navigation like the 530, 830, and 1030 series, but for the price, which isn't all that much more than a good non-GPS bike computer, it's pretty nice. It can be set up to upload your ride to Garmin Connect, Strava, and possibly other services at the end of each ride. With my 1030 Plus, as soon as I tap to end the ride, my phone chimes twice letting me know both Garmin and Strava received the ride data.

It sounds like if you do need mapping and navigation (which you may not), your phone would serve that need. But I do like the convenience of having it on the GPS.

noglider 

Thank you, everyone. I mostly wanted my inferences to be confirmed, and I think they are. I will take the sensor for its first ride today.

I'm happy with the setup I've been using and don't plan to spend much/any more money soon. It's an iphone 8 with the ridewithgps app and a Quad Lock mount. I recently added a heart monitor and am still experimenting with it. I rarely need navigation, and I'm happy with using either ridewithgps or google maps for that. I had a Garmin Edge 200 a few years ago, and a dedicated computer is nice, but I'm not inclined to get one soon.

@Tourist in MSN, thanks for that idea. I've used some ultra-cheap wired computers, such as the SunDing. It sometimes sells for as little as $3, and it works like a champ. I could try that for speed readouts just for fun. Generally I prefer things that move easily from bike to bike since I have (too) many bikes.

gkamieneski

I have a couple of the Moofit speed sensors from Amazon. I am pretty sure I set the tire size and diameter in the app, and I would expect your speed sensor should be set up in the same manner.

Tourist in MSN

Sometimes when I just go for an exercise ride, I leave the GPS at home. The wired computer on my rando bike is from a company that went out of business about a decade ago, but I like it. I bought a few extras of the same model computer on clearance sale later. Battery (only one CR2032) lasts for years, and it just keeps going, and going, and going. I have the same computer on one of my touring bikes too.

I hope you realize that on this forum, saying that you have too many bikes is sure to draw copious rebukes.

noglider 

Yes, I realize that. I'm prolific in the C&V section where people know me and my bikes well. Recovering from some serious dysfunction, I have gotten the collection down to nine bikes, and I haven't acquired any bikes in some time. I think it's fairly stabilized now.

noglider 

I put the sensor on my front wheel and made sure my app still knew about it. For fun, I also hooked up my new heart monitor, also over bluetooth.

I rode up and down my road for a few minutes. The question entered my mind: how do I know if the new sensor is working? Until now, I have always had a speed readout. Well, I figure that the readout should update more quickly and accurately. It did not appear to act any different, so I doubted that it was working. For instance, I would get up to a speed of 17 mph, and it took a few seconds to reach that in the display, and then I braked hard, and the display went down in two steps over several seconds.

I uploaded the ride, and it shows me starting out at some high speed, dropping down to 7.8 mph, up to 10.3 mph, and then dropping down to NEGATIVE 2.2 mph and staying there for the rest of the 1.3-mile-long ride. It says my average speed for the ride was 236.9 mph. So the sensor data has replaced the GPS data for speed after uploading, AND the sensor data is bogus.

Here are my tracks.

I'll put in a support request with ridewithgps. The folks there are pleasantly responsive.

noglider 

Aha, there is a place to enter wheel circumference. The response from Dave at RWGPS was quick. I entered the circumference and will test it again.

Unfortunately, I will either need to re-enter circumference each time I change bikes or deal with the imprecision from not re-entering it. Life goes on.

DiegoFrogs

Any time my average speed goes above about 225 mph, and my heart rate doesn't need scientific notation, I count my blessings.

canklecat

Incidentally, regarding using bike computers and sensors on indoor trainers, sometimes it works, sometimes it doesn't.

The XOSS G+ computer won't help much on the indoor trainer. Despite using a speed sensor on the wheel and seeing a speed readout on the computer, it depends on GPS sync to deliver any useful data, which limits it to outdoor rides (and runs, although it isn't intended for that purpose).

So I still use my old iPhone 4s with 2012 era Wahoo ANT+ adapter and speed/cadence sensors for the trainer, using the Wahoo Fitness app on the phone. I mostly use my Centurion Ironman on the trainer, already set up to log indoor sessions.

I can tell from Strava logs posted by friends when they're using their old school rollers for indoor trainer sessions. They get little or no data to post, just a time elapsed and approximation of effort. I'm not sure which Garmin or Wahoo computers they're using, but they don't record accurate activity on the older trainers. Occasionally they'll post a log with GPS data, but it's just a bunch of zig-zags on a map over their location.

noglider 

Today, ridewithgps didn't seem to see the presence of the setting but it's hard to know for sure. I didn't get a bogus reading, but does that mean it works right? I'll ask support.

My GPS tracks

@DiegoFrogs, good points. I think I agree.

noglider 

I got excellent support from ridewithgps. I pointed the customer support representative (CSR) to this thread, and it ended up being useful to him in diagnosing the problem. It isn't possible for normal users to separate data from speed sensors from data from GPS, but it's possible for a CSR to do it, and he confirmed that my sensor is working properly. You do have to calibrate the sensor to wheel circumference. I measured the rollout on my kitchen floor using an unloaded bike, and I think that's close enough. Unfortunately, I have bikes of different tire diameters, so I won't be moving the sensor from bike to bike often. But I now know how.

Iride01 

Actually it is possible for "normal users" to see the sensor data and GPS data. However you need to get a template that can let the data of the .fit file be parsed out into a human readable form. I used to have one for microsoft access that I got a long time ago... something like ten years or so.

You could also get the developers kit for Ant+ and build your own program to get the data.

But I guess this all hinges on what you consider a "normal" user.

noglider 

Good to know. I don't feel inclined to research how to do this, but I'm glad the data is there. And I get your joke. I'm often abnormal in that way.

njkayaker

Golden Cheetah should let you see all the data in the fit file.

noglider 

I googled that and discovered it's an app. I'm installing it now on my computer. Thanks for that. It might be fun.