In reply to Dave the Rave:
Okay so cautionary tale time.
When I finally 'became an adult' (got married, moved to the 'burbs etc) we got a dog; a 3yo labrador cross with insane amounts of energy. One sunny spanish day, a couple of months after I got her, I took her out mountain biking on my local trails, and very nearly killed her.
We got to the bottom of a long downhill, and when I paused to let her catch up, after she reached me she just collapsed. I chuckled initially, pleased that I had finally manage to tire her out, but after a while I got worried. I had water and a bowl for her, but she could barely drink it. In the end we stayed there a full half an hour, she gradually polished off a half-litre of water, and finally managed to get up for us to walk the mile-or-so home (I pushed!)
I thought I had learned my lesson, but two years later my wife and I went on a (hilly) fireroad ride, and to cut a long story short, we were very very glad to find a big stream at the bottom of the last hill, into which an overheated dog promptly plopped herself down and refused to move for 20 minutes.
Moral of the story(ies):
- the bits you find easy (freewheeling down fireroads) are the hardest bits for pooch
- take loads and loads of water, and a receptacle from which pooch can drink
- stop frequently, and make sure pooch is not lagging
- pooches LOVE LOVE LOVE coming mountain biking with you, but are incapable of telling you that they're exhausted, because a) they're dogs and b) they're having too much fun
Once I learned these rules, dog and I had many great days out in hills. She is now 9 year old and can't keep up with me over a 5km run even, so I don't take her out biking any more. But we had fun, and I'm going to give her a big cuddle right now, thanks to the memories