Hello!
I don't know if this is a valid thread anymore, but as I had the same issue with my Apple Watch's outdoor cycle activity and I didn't find a specifically helpful answer from this thread, I thought I'd tell everyone how my problem got solved. If moderators think this is not a necessary post, then it can be removed.
Firstly, I bought a used Apple Watch couple of months ago. It worked fine with my iPhone 5S when I was going for a walk or a jog. On the iPhone I used also Abvio's Walkmeter -app, and both the app and the Watch's outdoor walk/run worked simultaneously just fine. However, I didn't use the cycle activity, only walk and run.
Then I bought an iPhone 6S recently, and I had to pair the Watch with the new phone and because of this it for some reason returned to factory settings. It wasn't that big of an issue. When I took my bike for the ride for the first time after winter and tried to measure my rides the same way as I did with the walks and runs, I faced the same problem as in the first post of this thread: all I got was "----" for the speed and the distance. I used the Walkmeter at the same time as I did with walking and running and it was working as usual.
I read this thread and kept cycling with the Watch's activity on and with Walkmeter. I cycled for about 60km and it did not give me anythin else than the same "----". However, I noticed that regardless of this, it did show me afrer I finished the activity, that the best achievement (or exercise) was exactly the same what the Walkmeter measured. I think the Watch's activity app somehow got the data from the Walkmeter, even though they are not connected in any way as of my understanding.
Couple of days later after I had a quite long cycle, I decided to try the Watch's activity without the Walkmeter and for my surprise it just started to work! Then I downloaded Abvio's other app, the Cyclemeter (witch is practically the same as Walkmeter, but designed better for cycling only; the Walkmeter has an activity for cycling also, so there's no real difference between the two). The Watch worked with it too just fine. Then I had the courage to try it again with the Walkmeter and it worked too!
So all and all, I think it was just about the calibration. The Watch needed enough rides to learn some movements while cycling, or something like that. I really don't know of this is actually the case, but I got it to work like this. I didn't reset anything, not the Watch nor the Phone. I was just patient with it.
I hope this helps!