I have the same problem - especially on the tele side. I live in Sweden, and we cycle in both open and wooded areas. I have rented the 70-200 f2.8 - ok, but too heavy to carry around - especially since I'm also biking. Borrowed the 70-200 f4 which is OK sometimes, but in the wooded areas it's not good enough.
Got a recommendation to use the Canon 135 f2 L, but I haven't tried it yet (can't rent it locally).
Ended up buying the 70-200 f4 as an all purpose tele lens, because just like you I shoot mostly on the wide side - (well, actually on 28 mm on a 1.6 crop, which is not that wide). I did some quick financial calculations and quickly understood that the best mtb tele for me is my legs - move in closer if you are in the woods. And use a flash or two. But if you insist on a tele in the woods, and you've got the money, try out the 135 mm prime, and let me know the results.
On the wide side - Are you using a flash? I use flash a lot of the times because on so many shots the riders are looking down at the ground and the flash is needed to lighten up the faces. That's also something to factor in if you are going to use the tele. So 17-40 with a flash should be OK
I just got a 10-22, which I'm going to try out when spring comes along. I'd like to get a little bit wider than today - I'm not expecting great things from it, but we'll see if I can figure out a good set up with some flashes. Will get back on the forum about that when that happens.
Also - when considering what lens to buy you also have to factor in the cost for the next bike. The next bike is always going to be more expensive than the next lens.