Originally Posted by
NothingTooFancy
at 9mph (your current speed) it would take you 80 minutes to do 12 miles. If you got a road bike you could probably up your speed to 15mph (thats a fairly conservative estimate) which would translate to a 49 minute bike section.
I just changed from a mtn bike to a road bike over last summer. Would be able to ride 10 miles in about 34-36 min. On my road bike I only dropped about 3-4 min off that time...maybe +1 mph average.
Will a road bike make you faster? NO.
Will a road bike make your time better? Yes, due to less rolling resistance/better aerodynamics.
The only way to become faster is to ride more. Train and use the mtn bike for now and when you can ride that route in under 45 min on your mtn bike, look into a road bike if you want to keep riding and racing. I was averaging 16+ mph on my mtn bike for 20-25 miles before I bought my road bike.