Hi all,
I have an old mountain bike (15 yrs old or so) with Biopace eliptical sprockets. A friend of mine mentioned the other day that eliptical sprockets can be hell on your knees. After having this bike for most of it's life, I've not had a knee problem, but is this something to consider? I'm in my mid 30's, and don't wanna screw up any major joints...I use it to commute to work (10 miles RT) and to do some extra riding in Central Park occasionaly.

I'd like to get up to riding 15-20 miles per day, 4-5 times a week, if I can.

If I do decide to go with new sprockets, would it just be worth getting a new (and lighter) bike instead of doing an overhaul on a 15 year old bike? I really like it, but would look for a new one if only to cut a few pounds off the weight of it....

Any ideas on this? Thanks.
-coney