Modern long reach calipers on old bike, strong enough for safe braking from the hoods? Currently I am debating with what to replace the handle bars and brakes on an old bike. One option are drop bars. However, a concern is that braking from the hoods was unsafe in old bikes. However, I might be able to fit a recent Shimano front caliper and fitting levers (see below). However, the brake pads would be at the limit of the calipers reach at 57 mm.

Will modern Shimano levers and calipers provide enough two-finger braking power to safely ride from the hoods?

At the rear I shall keep the current Weinmann centre pulls. These work well enough for the back. Lever compatibility is another question, see the SE question on similar Dia Compe brakes.

Parts: Shimano BL-R400 levers and BR-R451 long reach calipers. Both are super SLR

Aluminium rims 622-19, 24 mm outside width



What reach is:


  The effective length of the arms of a caliper brake. This is measured from the centerline of the center bolt diagonally down to the middle of the brake shoe. Reach is commonly expressed as a range (allowing for the fact that the brake shoes are adjustable, typically over a 10-15 mm range.) For more information, see the article about caliper brakes.


From Sheldon Brown's knowledge base
I got the Shimano  BL-R400 levers for my bike and they work great with my Dia Compe centre pulls brakes so I see no reason why they wouldn't work with your Weinmann brake which is similarly designed. 

Using the center pull brakes combined with the new levers provides ample braking power both from the hoods and the drops. I can't speak as to how well the braking would work for modern calipers. 

That being said, the BR-R451 calipers are only "long reach" by modern standards. There are calipers with much longer reach available if you need them. The braking power shouldn't really be effected too much by the length of the caliper.  A longer caliper arm will tend to flex more, but the arm on the BR-451 isn't even really that long.  They have been designed by a quality manufacturer who would taken into account the longer arm and design the brake with the right type and amount of material to resist excess flex in the lever arm.