Hi Catherine -

I took up dog scootering in November. I too have a "bionic knee". That
leg has always been chronically understrength (have been bionic for 20
years now) but the dog scootering actually helps with that as long as
your knee issues are in the ACL/MCL/LCL arean and not the pattellar
tracking arena at least.

It's close what the docs call "closed chain exercise" like riding a
stationary bike except a lot more fun, pretty much. OK, there is som
eshock absoprtion if you're riding rough trails, but pretty much, you
kick 3-5 with one leg, switch legs and kick 3-5 with the other leg. As
long as the scooter platform isn't very high, and you concentrate on
keeping your body upright, you get lots of shallow knee bends with no
torque and a bit of rest between short "sets".

As for dogs and pulling, the rule of thumb is that a dog can pull 3x
his body weight. I believe that probably varies from breed to breed -
I run German Shorthiar Pointers and they are speed machines.I have
some video on Google Video.If you do a Google search on "GSP Scooter
Dogs" and then click the video link above the search box it will bring
them up.

Anyway, as one cyborg to another, I recommend the two wheeled dog
scootering. Just be sure to get a scooter with good brakes. The Torker
looks attractive because it's inexpensive, but it has nylon/plastic
rims, and its stopping power ain't so hot. Looks like the Diggler Dirt
Dawg is a bit better for that plus it has a front shocks. It's $175
and if you get it from Diggler, you get free shipping (at least for
now). If I hadn't already bought about 82 scooters trial and error -
I'd either do that one next or splurge for a Blauwerk Mountain or a
Kickbike XC.

Also, the harness and tug line make a big difference. You want a
padded harness (you can always sew fleece onto a pet store harness,
but custom harnesses aren't thA pricey if you shop around). Also,
there has to be some bungee in the tugging system between the scooter
an dthe dog. It makes a huge difference in the experience. Less
jerking (whwich feels like a correction) for the dog and a smoother
more relaxing ride for you.

All this stuff I have gotten from trial and error and from helpful
"veterans".

GoodLuck!