Just to echo James,
welcome Pip, my first ride I averaged about the same speed, but on the road (off road as never interested me) so I reckon thats good going, and as you say it will get easier. As for noises try and and note if there is a regularity to them, but your front wheel, wheel catching on brakes, either recentre brakes or check for trueness of the wheel, or bearings and spoke tension.
Brakes and spokes will happen each revolution bearings possible most of the time, but again could be each revolution.
Now I know who to blame to for getting hailed on James, thanks
.
Well another 50Km ticked off, less than 100Km left, barring anything else going wrong.
New shorts well what can I say, I was no more uncomfortable at the end of the ride as I was when I set off, if anything I was more comfortable, and for once the 50km didn't seem far enough even given the conditions, and guess what the Sun is trying to shine, one other thing, though a little tight round the waist ( I measured 33" the other so got a medium, even having read reviews and to get a larger size), the legs were fine and even kept my leg warmers in place unlike my other shorts, so maybe it's just people not being used to how tight cycling shorts are meant to be, maybe someone can correct me.
I have lost track of how many p.b's I have got since the new wheels (sorry to mention them again, but I can't believe the difference)
http://app.strava.com/activities/50928642