"ANT+/BT4 transmitters are cheap and simple and are available right now."

except Transmitters are useless without a reciever.

and even the CHEAPEST droid phone can handle "ANY" cycling demands without even breaking a sweat from a horsepower perspective. think about if you can buy cycle computers for $4 how much horsepower do you think those things have? all their doing is counting pulses. literally. thats it.

the slowest droid I am aware of is 600mhz. how fast is that $4 cycle computer? 4mhz ? if that? all it has to do is "count" and reference a table of values.

I doubt it will go anywhere but I am going to look into a homebrew option just to see how feasible it is. I can't do software but I can do "some" hardware see if I can find anyone to help.

do I need cadence and stuff like that?

careful there buddy need is a powerful word. the only thing I "NEED" is food, water, air and some shelter depending on what region of the planet I am in.

by definition ANYTHING else is a "want"

I WANT to be able to do this stuff.

what irks me (again) is that I have this insanely powerful computer and a $10 adapter that no one has made is the only think stopping me from doing some neat things with it.

trust me $40 for that cadence sensor is massively over priced versus "unit cost" but most likely that company has a lot of "up front start up" costs to offset so its understandable.

Regular BT is already "cheap and mature"

like I said. because of how cheap it is I am surprised no one has made anything. not even the chinese makers. just seems "odd"

There is no question its possible and feasible. I don't mean to insult but thats not even up for discussion I know enough about the tech and how to do it to KNOW its very feasible and possible.

I can only think of 2 reasons no ones done it.

no one thought of it (smart phones of this caliber ARE really very new still)

or more likely. the market really is just that small that they must shoot for the "high end" first to make a real profit.