@cascadewheeler Thanks, that's a good suggestion in the meantime.
But I agree with OneDan+: it's too inaccurate, too slow/laggy, and it requires GPS cover to begin with. Won't work at all in a tunnel for example, and many other places.
Perhaps a slightly better solution would be to hack the ponewheel app (https://github.com/ponewheel/android-ponewheel). It already knows the wheel speed.
@OneDan+ A while back on the Facebook page, a few folks found the smallest droid watches that could run the app without needing a phone. So you'd have a cheap watch doing what your phone is doing there. Another option if you're just looking for real time speed.
I use an Apple Watch and so far it's been great. After a while you may develop a better sense for your speed without the need for an app... but it is something you have to be wary of at all times.