Speed and cadence sensor

netshock122
netshock122 Posts: 11 Member
in Fitness and Exercise
Hi Guys,

I have an exercise bike that has no hub (or at least not an accessible hub) - so my question is, are there any speed sensors that go on the crank? I see cadence do, but I wanted a speed sensor so I can play the virtual cycling games,

Thanks!!

Replies

  • misskris78
    misskris78 Posts: 136 Member
    I have a Wahoo RPM that goes on the crank on my indoor bike. Pairs well with Zwift.
  • netshock122
    netshock122 Posts: 11 Member
    Thanks. So yours is the RPM cadence sensor right? Looks like the RPM speed needs to be connected to the back wheel
  • BrianSharpe
    BrianSharpe Posts: 9,248 Member
    edited April 2020
    misskris78 wrote: »
    I have a Wahoo RPM that goes on the crank on my indoor bike. Pairs well with Zwift.

    For a wheel that doesn't have a hub you'd need to track down a magnet based speed sensor (magnet mounted on wheel, sensor on fork).
  • netshock122
    netshock122 Posts: 11 Member
    Ah, I mean, it doesnt even have a wheel really, it's all encased so I cant access it. The only place i can add such a sensor is on the pedal really
  • sijomial
    sijomial Posts: 19,809 Member
    netshock122 wrote: »
    Ah, I mean, it doesnt even have a wheel really, it's all encased so I cant access it. The only place i can add such a sensor is on the pedal really

    The Wahoo RPM speed sensor is designed to fix to a wheel hub, the Wahoo RPM cadence sensor is designed to be fixed to the pedal crank or your shoe. Not sure if the speed sensor would work mounted very differently or how it would interpret the very different movement. Maybe you could tell whatever device you are linking to that a pedal or shoe mounted cadence sensor is a speed sensor - maybe?

    If it did work it still isn't a true reflection of "speed" - you might be able to calibrate it to make yourself a cycling god and win those games!
    Pedalling cadence and "speed" (effort in reality for indoors) aren't related.
    You could be spinning your legs with no resistance at 100rpm barely putting any effort in or grinding against maximum resistance at 40rpm busting a gut.
  • netshock122
    netshock122 Posts: 11 Member
    Thanks for the advice :) I'll have a think what to do
  • Jthanmyfitnesspal
    Jthanmyfitnesspal Posts: 3,522 Member
    Yep. If you really want to Zwift, you have to get one of the newer calibrated trainers. My trainer is old-school and just adds some reasonable resistance without very much calibration. It has been highly reliable, and the speed is pretty close to what I achieve outdoors (+/- 2mph). I have Wahoo Fitness cadence monitor on my shoe and a speed monitor on my rear hub.

    I also go to spin classes that use un-calibrated standard spin bikes (when I'm not in quarantine, that is). My cadence monotor still works, but there is no speed output. The "speed" of a spin bike is pretty arbitrary, anyway, since the resistance is totally arbitrary based on the brake knob.

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