Is a speed sensor needed with GPS cycle computer?
rumbataz
Posts: 796
I'm trying to understand whether or not a speed sensor is required if you have a cycle computer with built-in GPS?
I would imagine that the computer would prioritise the paired speed sensor over the GPS. Would it be more accurate or would the speed sensor just be a waste of kit to attach to my bike if I purchased a cycle computer that had GPS?
My rationale is that I want to avoid cluttering my bike when the function the additional accessory is already provided by the cycle computer.
I would imagine that the computer would prioritise the paired speed sensor over the GPS. Would it be more accurate or would the speed sensor just be a waste of kit to attach to my bike if I purchased a cycle computer that had GPS?
My rationale is that I want to avoid cluttering my bike when the function the additional accessory is already provided by the cycle computer.
0
Comments
-
If you have a sensor, your speed and distance will be measured more accurately. You'll also avoid the very high speeds that are sometimes recorded when the GPS signal is lost momentarily. I have a sensor on one bike and never get the unbelievable speed spikes, on another where I don't have a sensor I've hit 90kmh+ when I know I didn't go over 60.0
-
Agreed, the speed sensor will be more accurate - especially in situations where the GPS signal is lost - eg. tunnels etc.
Also, if you use a turbo trainer at any point, it will be useful for any subsequent analysis eg, trainerroad, TP etc.0 -
Ah okay, thanks for the advice. I couldn't really see any obvious benefits originally.0
-
Well I have a Garmin and rely only on GPS. In 18 months I've never got any spurious speed readings. Not many tunnels round these parts...
It occasionally records HR that's clearly inaccurate: 150% of my max HR as soon as I leave the house; put that down to my shirt flapping against the HR strap.0 -
Not only tunnels - tree cover can affect it and low speed is inaccurate too - so speed when going up hills isn't reliable - if that doesn't matter then no speed sensor required - I don't bother with one on my commute , mountain or winter road bikes, but I do on my road & TT bikes ... There's one tree-covered hill on my commute onwhich my reported speed varies hugely on my commute bike despite constant cadance, but very steady on my roadbike - as it's a commute it really doesn't matter ...Well I have a Garmin and rely only on GPS. In 18 months I've never got any spurious speed readings. Not many tunnels round these parts...0 -
Biggest difference I found was that when using GPS, the auto-pause and auto-resume lag just slightly while it makes sure you really are/arent moving, in case it is just normal GPS drift. Wheras using the speed sensor it starts/stops immediately.
It does also give more accuracy in that GPS is always subject to a margin of error and has to calculate distance travelled due to altitude change - its very clever at doing all that and gets pretty close, but not as close as something that reliably measures wheel rotation and is well calibrated (calibration is done automatically over a distance by Garmin devices).
And yes, there are sometimes loss of signal issues on my mountain bike due to trees etc and while I dont do tunnels, they would be another occasion.0 -
Just remember folks - you get faster Strava times on an iPhone.0
-
One thing to remember is that if you use a power meter you don't need (and shouldn't have) a separate cadence sensor, so if you want better speed accuracy, you need a dedicate speed sensor, not a combined unit.0
-
I just leave the crank magnet off.One thing to remember is that if you use a power meter you don't need (and shouldn't have) a separate cadence sensor, so if you want better speed accuracy, you need a dedicate speed sensor, not a combined unit.
0 -
I've got a Garmin 500 and a speed/cadence sensor on two of my bikes, but I use it mainly to measure cadence as the GPS speed and distance readings are the same when just using the GPS on my other bike. When commuting I use an older Garmin 200 - the speed/cadence sensor doesn't work with that, but still records distance and time accurately.0
-
Or with a Garmin - it reads the power meter cadence in preference to the combined speed/cadence sensor reading - so it doesn't matter ...
I just leave the crank magnet off.One thing to remember is that if you use a power meter you don't need (and shouldn't have) a separate cadence sensor, so if you want better speed accuracy, you need a dedicate speed sensor, not a combined unit.0 -
I found that if I left the crank magnet off, my 800 would record no cadence at all. To get it to see the cadence from my PM (Rotor LT) I had to unpair the GSC-10.
Or with a Garmin - it reads the power meter cadence in preference to the combined speed/cadence sensor reading - so it doesn't matter ...
I just leave the crank magnet off.One thing to remember is that if you use a power meter you don't need (and shouldn't have) a separate cadence sensor, so if you want better speed accuracy, you need a dedicate speed sensor, not a combined unit.0
