Originally Posted by
gugie
Not seeing how a longer reach brake in the rear helps you get the top tube lower.
Having a short reach brake in front gets the top tube lower.
Start from the default position of, oh, 1946. Size small for mens frames is usually 54cm. Both brakes are long reach. Shorter riders can't stand over the bike. Shorter riders don't want to ride ladies frames. Now figure out how to get top tube lower. This is about as self evident as it ever gets. Stop living in mental universe where all riders are over 6' and all ride frames 2cm to 6cm too big.
When decision is made to alter front end of bike sheer inertia keeps rear brake bridge right where it was. Also simplifies fitting of the rear fender.
The wife's '73 Colnago, 51cm c-t, has a standover of 28-1/2". Front brake is short reach, roughly 44mm. Rear is standard reach, 52mm. Ernesto spends an extra lira or two to get Campy to provide mixed length brake calipers. Because he buys a lot of these brakesets, uses them on all the bikes, it is one lira cheaper than if he bought some mixed sets and some matched sets. And short reach on front makes the bike look racy.