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Speed sensors

Old 05-31-19, 09:40 PM
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bonsai171
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Speed sensors

Does anybody have 1 speed sensor they swap between multiple bikes? I have 3 bikes, trying to decide if I should get 3 speed sensors or just move around the one I have.

Dave
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Old 05-31-19, 09:53 PM
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What kind of speed sensor are you talking about? Bluetooth?, magnetic?
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Old 05-31-19, 10:27 PM
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I have a GPS speed sensor I used on my bike, skis, and on rental bikes. A wheel or hub magnet seems like it would be tedious to move around.
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Old 06-01-19, 12:44 AM
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It is the Wahoo speed sensor. It wraps around the front or rear hub with a thick band that stretches. It is Ant + and Bluetooth.
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Old 06-01-19, 04:33 AM
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Garmins are GPS so you don't need a speed sensor.
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Old 06-01-19, 06:56 AM
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Originally Posted by oldnslow2
Garmins are GPS so you don't need a speed sensor.
I'm actually using a Wahoo Elemnt Bolt. Right now 1 bike has the external sensor, the other two don't. We have a 95 mile bike trail down here that I ride often, and there is heavy tree cover. In some areas the speed will fluctuate (will be riding a steady pace of 16 mph, then the speed will drop down to 10 or 0 then go back up). Works better on the bike with the external speed sensor. I suspect the same will happen while mountain biking (had some dropouts riding gravel thru areas with heavy trees last weekend without an external sensor too).

Dave
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Old 06-01-19, 07:13 AM
  #7  
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So unless you're training or a "Strava nut" does it really matter?

If it does then does moving the sensor from bike to bike more trouble than buying 2 more sensors?

I have 2 bikes and the Garmin supports multiple bike profiles. On my road bike i have a single sensor that does both cadence and speed. On my CX bike I only have a cadence sensor and speed is via GPS. I never noticed any inconsistent speed issues.
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Old 06-01-19, 08:54 AM
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I'm sorry, I don't understand your objective. I have the same Bolt/sensor combination as you. You can swap sensors between bikes, or rely on GPS for the two bikes that don't have the sensor. Keep in mind that each time you swap, your Bolt has to recalibrate for differing wheel sizes (assuming you're on auto-calibrate) and this might lead to measurement errors until the calibration is complete.

Originally Posted by bonsai171
I'm actually using a Wahoo Elemnt Bolt. Right now 1 bike has the external sensor, the other two don't. We have a 95 mile bike trail down here that I ride often, and there is heavy tree cover. In some areas the speed will fluctuate (will be riding a steady pace of 16 mph, then the speed will drop down to 10 or 0 then go back up). Works better on the bike with the external speed sensor. I suspect the same will happen while mountain biking (had some dropouts riding gravel thru areas with heavy trees last weekend without an external sensor too).

Dave
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Old 06-01-19, 10:42 AM
  #9  
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Originally Posted by Robert A
I'm sorry, I don't understand your objective. I have the same Bolt/sensor combination as you. You can swap sensors between bikes, or rely on GPS for the two bikes that don't have the sensor. Keep in mind that each time you swap, your Bolt has to recalibrate for differing wheel sizes (assuming you're on auto-calibrate) and this might lead to measurement errors until the calibration is complete.
That was helpful. I was hoping to avoid buying 2 more external sensors at $40 each, but it sounds like it might make sense to do eventually for my situation.

Dave
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Old 06-01-19, 10:48 AM
  #10  
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On my road bike I have speed and cadence sensors for my Garmin Edge 820. On my hybrid/commuter I do not. I do move the GPS from bike to bike, but I don't move the sensors: The cadence sensor is too hard to unmount and remount to do it frequently. The speed sensor is easier, but would require that the GPS recalibrate each time.

I considered getting a set of sensors for the hybrid/commuter but two problems: One, sometimes my brother borrows the hybrid to ride with me. My GPS would pick up both sensors whenever we're within fifteen feet of each other, and that would be really annoying. The other reason is... who cares. It's a hybrid/commuter. I do my fitness training on the road bike.
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Old 06-01-19, 12:47 PM
  #11  
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I use a Garmin 1000 on 5 different bikes. I have a speed sensor on my plastic road bike, as I often ride in a group where being able to maintain a constant and steady speed is important. A speed sensor in that scenario lends to more accurate speed indication when using a GPS only has a lag as to the current speed. I also use speed sensors on my mt. bikes, as riding in heavily wooded area's or when riding on trails that have a lot of tight and twisty turns, lends to a more accurate distance track. I do not have or need sensors on the 2 bikes I use for commuting.
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Old 06-01-19, 01:51 PM
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Originally Posted by oldnslow2
So unless you're training or a "Strava nut" does it really matter?
Actually, if you're a "Strava nut" it's completely irrelevant. Strava disregards speed sensor info and only goes off of GPS, so the sensors would only be for the benefit of the Bolt.
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Old 06-01-19, 01:53 PM
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Originally Posted by WhyFi
Actually, if you're a "Strava nut" it's completely irrelevant. Strava disregards speed sensor info and only goes off of GPS, so the sensors would only be for the benefit of the Bolt.
Didn't know that.
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Old 06-01-19, 04:37 PM
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Originally Posted by WhyFi
Actually, if you're a "Strava nut" it's completely irrelevant. Strava disregards speed sensor info and only goes off of GPS, so the sensors would only be for the benefit of the Bolt.
Yep - I gave up on them a while ago for precisely that reason. It smooths out your speed display on your head unit. Big whoop.
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Old 06-01-19, 09:53 PM
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Originally Posted by TrojanHorse
Yep - I gave up on them a while ago for precisely that reason. It smooths out your speed display on your head unit. Big whoop.
Sounds like $80 saved for me if the Elemnt bolt works well on mtb trails!

Thanks everyone.

Dave
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Old 06-01-19, 11:01 PM
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Originally Posted by WhyFi
Actually, if you're a "Strava nut" it's completely irrelevant. Strava disregards speed sensor info and only goes off of GPS, so the sensors would only be for the benefit of the Bolt.
That's interesting. I guess if you think about it, be they need the GPS data to figure out when you came into the segment and when you left.
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Old 06-01-19, 11:06 PM
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Originally Posted by WhyFi
Actually, if you're a "Strava nut" it's completely irrelevant. Strava disregards speed sensor info and only goes off of GPS, so the sensors would only be for the benefit of the Bolt.
My Bolt gets data from my speed sensor and uploads the ride directly to Strava. The resulting data on Strava and my Bolt are 100% identical, so Strava IS pulling speed sensor data, at least in my setup.
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Old 06-02-19, 05:13 AM
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Originally Posted by Robert A
My Bolt gets data from my speed sensor and uploads the ride directly to Strava. The resulting data on Strava and my Bolt are 100% identical, so Strava IS pulling speed sensor data, at least in my setup.
You're right - looks like I misspoke. Strava segments disregards speed sensors, but it looks like I was wrong in thinking that they were completely disregarded.

Then again, KOMs and PRs are *everything*, so really... I'm still right.
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Old 06-02-19, 06:02 AM
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I personally don't see the need for speed sensors with a GPS head unit. The average speed results I get off of GPS are very consistent with those from people I ride with who have speed sensors. I get that there's a lag while accelerating / decelerating but this appears to work itself out over time. Instantaneous speed doesn't seem very important to me, especially given that I have instantaneous power and instantaneous heart displayed on my head unit, both of which are better measures of effort. Regardless, the speed updates in a second or so.
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Old 06-02-19, 06:40 AM
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Originally Posted by Hiro11
I personally don't see the need for speed sensors with a GPS head unit. The average speed results I get off of GPS are very consistent with those from people I ride with who have speed sensors. I get that there's a lag while accelerating / decelerating but this appears to work itself out over time. Instantaneous speed doesn't seem very important to me, especially given that I have instantaneous power and instantaneous heart displayed on my head unit, both of which are better measures of effort. Regardless, the speed updates in a second or so.
There's also the other added bonus. Better battery life.
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Old 06-02-19, 06:52 AM
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Originally Posted by Hiro11
instantaneous heart displayed
Actually the your heart rate lags as it takes a minute for your heart to get up to speed when you start to climb and a few minutes for it to come back when when you reach the top.
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Old 06-02-19, 05:41 PM
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Originally Posted by Hiro11
I personally don't see the need for speed sensors with a GPS head unit. The average speed results I get off of GPS are very consistent with those from people I ride with who have speed sensors. I get that there's a lag while accelerating / decelerating but this appears to work itself out over time. Instantaneous speed doesn't seem very important to me, especially given that I have instantaneous power and instantaneous heart displayed on my head unit, both of which are better measures of effort. Regardless, the speed updates in a second or so.
I tend to agree, and I probably wouldn't have bought one were it not for the HR and cadence sensors that came together in the package.
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Old 06-02-19, 08:22 PM
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I have a speed sensor on one bike, haven't seemed the need to put in on the others. I probably wouldn't buy another one either. Its nice when the GPS gets wanky from time to time but that is pretty rare anymore. Its more accurate but how accurate do you really need to be on the speed?

Power I want accurate, speed if its off just a touch, I am alright with that.
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Old 06-03-19, 07:08 AM
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Originally Posted by Robert A
My Bolt gets data from my speed sensor and uploads the ride directly to Strava. The resulting data on Strava and my Bolt are 100% identical, so Strava IS pulling speed sensor data, at least in my setup.
Mine does too, however I have noticed on a few rides that have uploaded, that the average speed in Strava has been .1 mph on the low side. Example, sometimes a 20mph average on the Bolt with a speed sensor shows up in Strava as 19.9 mph. Not sure what is going on there.
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Old 06-03-19, 08:34 AM
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Originally Posted by jadocs
Mine does too, however I have noticed on a few rides that have uploaded, that the average speed in Strava has been .1 mph on the low side. Example, sometimes a 20mph average on the Bolt with a speed sensor shows up in Strava as 19.9 mph. Not sure what is going on there.
The most likely cause is that Strava and your Bolt have different thresholds for what they consider to be moving, so average moving speeds will sometimes be different between the two.
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