Polar CS100
The Polar CS 100 is a really good unit, it does HR speed, distance and all the usual readings plus you can add an optional wireless cadence sensor to add that function too.
I found this on the web and appears the whole kit inc chest strap, wireless speed and wireless cadence sensor can be had for around £80.
[url]http://www.heartratemonitor.co.uk/polar_cs100_hrm_bike.html[/url]
I used one of these for about 2 years with no hassle at all, and have only changed as I upgraded to a Garmin Edge 705, to be honest I have times when I consider putting the Polar back on!