Hi Phil, well the speedo is very optimistic and hence something which I rarely look at, but Imdid some tests with a gps app on my phone which I stuck to the bike and it showed around 32mph on the flat using the red setting, the green gives around 27mph and amber is around 29mph.
I haven’t noticed any degradation of speed since new, and I’m guessing (as it doesn’t have a milo meter) that I’ve done around 300km so far.
I Weigh around 85kg but I’m 6ft tall so I catch a fair bit of wind resistance.
If you are only seeing 25mph downhill something doesn’t sound right, are you sure your power settings are actually changing when the light changes, have you flicked through them whilst travelling on the flat? You should feel the small step changes in power.