Is the dropout spacing the same for mtn bikes and road bikes? Or do I need to stick with mtn bike hubs and have a new set of wheels made? I would like to put skinny wheels on an old mountain bike to use for commuting.
The rear axle spacing on MTB’s is 135 mm.
The hub on 650c wheels is 130 mm. You could make it work on a steel frame, but the other issue is the braking surface radius, which is 6 mm greater on 650c wheels than on MTB wheels. You may not have enough pad adjustment…unless of course you don’t mind using your brakes.
Why not just install a skinny, high-pressure MTB tire?
Mavic makes a 700c disc-compatible wheel called the speed city. Easy to switch between mouontain wheels and road wheels.
Most road tryres are not tough enough for aggressive commuting. Just buy some narrow 26" mountain bike tyres that are designed for the job e.g. Vredestein S-licks (261.3), Continental sport contact (261.3) or Hutchinson top slick folding (261.0 or 261.2). I personally use an S-lick on the rear and a top slick foliding 1.0 on the front of my modified Cannondale bad boy commuter.
What on earth is aggressive commuting ? Is that where you ride over the top of cars and pedestrians ?
Aggressive commuting is weaving through traffic, pounding over rough tarmac, hitting unforseen potholes and throwing your bike round tight corners at 30mph irrespective of the wether conditions. All in a days commuting for me