Originally Posted by
ScaryPillow
20 mile distance, paved roads. How much faster would the road bike be?
Assuming that the mountain bike in question is kitted out for mountain biking*, a decent vintage road bike is usually nigh-identical in performance to a decent modern road bike, if you're comparing them to the mountain bike. That becomes especially true in solo rides, where things like the slower reaction of downtube/stem/barcon friction shifting doesn't really matter. The closest thing to an exception is if the vintage road bike is particularly heavy and the ride in question has a large amount of aggressive ascending.
*i.e. we're talking about a wide-flat-bar bike with knobby offroad tires, not a drop-bar conversion with slick road tires.
Originally Posted by
ScaryPillow
Given that there isn't much of a difference between the true mountain bike and the race bike, the diminishing return is astounding.
Most of us would say that 14mph vs 18mph is enormous. That's around 20 minutes on a 20-mile ride! If you're going 14mph and someone passes you at 18mph, it feels like they're going
substantially faster.
But, the diminishing returns are pretty steep between road bikes.