Can anyone recommend a good speedo?

Thanks in advance for any replies...

Have a look at Garmin 705 edge i got one a few years a go all the info you will ever need .

Need more info to make a good recommendation. What data besides speed do you want?

If it is just speed, time and distance then a small unit mounted to your bike is sufficient. I got one from my LBS that mounts on the handlebar and for input has a small magnet mounted on a front spoke with sensor mounted on a fork. Gives me speed, max speed attained, distance, total distance, time of day. Inexpensive and easy.

If you have an iphone there are several iphone apps that do more like show your track on a map which you can email to yourself or others... Also some GPS units will give you a map plus send sms messages by satellite to keep others posted of your progress. Expensive but if you are going on long excursions where there is no phone service then could be worth it. Could even save a life in an emergency situation.

I hope this helps

A simple and rugged unit for Mountain bikes is Cateye Enduro 8