Bicycle Mechanics - service drivetrain before or after longer rides?

i'm a "campus" rider that just started getting into fitness-oriented cycling, so basically every day i ride a couple miles to and from class, and once i week i go on a ~20mile ride. it seems like i'm putting more stress on the drivetrain on my longer rides since i ride to class pretty leisurely. is there any reason to believe that i should clean/lube before these "harder" rides as opposed to after?

Twenty miles isn't all that long. I typically lube my road bike chain after 4 or 5 60 to 65 mile rides. My mountain bike I'll do every 3 or 4 18 to 24 mile off-road rides. For either bike, I'll lube immediately after a wet ride.

My new road bike has 1800 miles on it and there is no sign of any chain stretch. I check it with a Park chain-stretch measuring tool.

Al

Agree with the canoe. The only logic I can think of to help you with the before/after decision is this: I clean and lube after a ride on the theory that it gives the lube a chance to work its way into the respective chain components and thoroughly dry.

Good luck with your increased mileage! Plan to ride a century!!

I typically have a weekly cleaning and lubing session no matter how much riding I have done. Now if bike gets wet or drity due to bad weather or off road riding following bad weather I will clean after that ride so that it isn't sitting on the bike.

For my fast, doesn't go out in the wet, roadie once a week is fine even if I have put 300 miles on it in that time.