It will probably be a series of 3 injections, one a week for three weeks, usually done on the same day of the week. Depending on your age, you should probably do fine with them. They are definitely worth a try before you decide to have your knee scoped. typically, once you go that road, your knee is never the same (obviously).
Glucosamine is more of a prevention method, rather than a treatment, like Synvisc.
Everyone I've seen who has had the injections has had some level of improvement.
If pain on the bike is the big issue, definitely check your fit on the bike and shoes. Insoles and wedges may help. Some bikeshops have really good people to properly fit people. It's gaining popularity quickly, so it's more widely available now.
Good luck