At Windsor tri I managed 1:12 for 42 km (so just under 22mph) - and that's a mid-pack time for a bloke... the leaders were well under an hour - see full results here - http://www.humanrace.co.uk/results06/w06age.html
At Almere I did 3:50 for 120km (so just under 20mph - but that did include a pee stop and a snog stop?!)
But please bear in mind that just like with running, the speeds you cycle at in training are generally much less than you do when racing - I think most local chain gangs seem to head out for 16-18mph rides - and I'm lucky to average 15mph on my local solo routes.
At Almere I did 3:50 for 120km (so just under 20mph - but that did include a pee stop and a snog stop?!)
But please bear in mind that just like with running, the speeds you cycle at in training are generally much less than you do when racing - I think most local chain gangs seem to head out for 16-18mph rides - and I'm lucky to average 15mph on my local solo routes.