Originally Posted by
FBinNY
I can't say this enough. It's never been about stopping the wheel, it's about stopping the bike. The limiting factors have never been the brakes themselves, but tire traction, and geometry which determines the maximum front braking force that won't cause an endo.
Very true. My road bike has rim brakes, the MTB has hydraulic disc brakes.
When I'm riding the MTB the disc brakes will stop the wheel with minimal effort from me. That doesn't mean I stop any faster. Comparing the two bikes on the road (i.e. taking out factors like the lack of tyre traction on loose gravel etc), the road bike takes longer to stop the wheels but the bike stops at the same time. The MTB's brakes are powerful enough to lock the wheels which just means I slide to a halt. I don't ride the MTB much these days, so really have to be careful if I am riding on the road to get somewhere, because if I do misread a situation and have to brake hard the chances are I'm going to slide and if I slide the chances of sliding into something are increased.
The main advantages I see of disc brakes are that you don't wear out the rim, and it doesn't make any difference to braking if the rims get wet or muddy. Where children's bikes are concerned one major disadvantage is that if you bend the discs themselves the brakes will rub and from what I gather straightening the disc is the sort of thing that either costs money or takes a huge amount of time.