Weight training methodology depends on the results you want. There's an old adage that's true:

Low weight + high rep = Definition
High weight + low rep = Mass

So, if you're only looking to build strength, then doing a high weight to exhaustion in one set is fine. If you want chiseled abs and arms, then you'll need to do more at a lower weight.

Personally, I've been doing weights for about 30 years now, off and on (more on than off). Currently, I do weights 3 days a week concentrating on my upper body and abs. I leave the lower body and cardio to the bike.

For my upper body, I do different weights and reps on different days. On Mondays, I do a low weight, but do 3 sets of 20 of each exercise (except chest press, where I do 7 sets). On Wednesdays, I up the weights by 15-20 pounds but decrease the number in each set from 20 to 14. On Fridays, I up the weights again, this time to whatever I feel is a good max for the exercise, and do sets of 8. In terms of actual weight moved, I do more on Mondays than on Fridays. In terms of muscle building, though, I really feel like Fridays are the building days.

Remember that muscles are built by the process of tearing, or injuring, the old muscle fibers and allowing your body to repair them. This is why you need at least 24 hours between working the same muscle group.

For abs, I do sets of 20 no matter what day it is. I do incline sit-ups, crunches, leg raises, and "superman."

Always, always do stretching both before and after weights. You should do it before and after your ride, too, but as long as you warm up easily and warm down as you approach your finish, you're probably good on that. I spend about 45 min. on the strength training and 15 min. doing stretches.