chainrings...3 vs 2,why?

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:confused:
hope this isnt a dumb question!
but am confused.

i see some bikes w/3 chainrings and some w/2 chainrings.
most of the time i see 2/chainrings on dirt/jump bikes, or bikes that say comp or pro. i also see lots of kmart/target type bikes w/ only 2 chainrings.

i have noticed alot of folks remove the large ring in favor of a bash-guard.

what do you loose or gain[as the case may be] in having 3 or just 2?

can the bikes that have only 2 chainrings be used for the same things as a bike w/3 chainrings?

example:
specialized hardrock pro disc[2/chainrings[i think] vs hardrock comp disc[3/chainrings].
will they climb the same or do xc duty the same?[other than the difference in other components]

thanks all!!!!!! :D

just trying to understand.

Hi there - I guess the main reason riders run 2 chainrings is because they've replaced the 3rd chainring with a bashguard - which protects the remaining chainrings when you're crunching that area of the bike into logs/rocks on the trail. The bashguard also helps stop the chain from skipping off (the outside at least... it doesn't stop the chain from falling off the "inside", and getting jammed against the frame...)

Personally, I prefer my "crazy riding" bikes to have only one chainring, and run a chainguide to secure the drivetrain. I do this for my downhill bike, and for my jump/urban bike.

Hope that helps :)