Originally Posted by
jimmuller
I could tolerate that if only they wouldn't bother everyone else too!
First, thank you for the compliment. Second, trial, error and experience count for a lot. That's how one gets to be an expert! You have far more of it than I do. Book-larnin' goes only so far when it comes to making something work.
About those Weinmann Concave rims, we could look up the specs in Velobase or someplace, but my recollection is that they were very heavy. (Decades ago I had one on the rear of my UO8 for commuting through Cambridge. I never weighed it but I believe it made the bike feel sluggish. It lasted about a month before it pretzeled itself quite unexpectedly. So much for its supposed strength.) I don't know the World Tour tire, but from the name alone I would guess it to be heavier than a typical road tire. Finally, from the description of those 27" wheels I might even guess that it had thicker spokes, perhaps 2.2/2.0/2.2mm as compared to 2.0/1.8/2.0mm. Given those factors the 2.9lbs difference becomes more believable.
The OP's question was about brakes, but that's just part of the broader question of the 27" to 700c conversion issue. I have two bikes with 27" and I haven't converted them simply because I couldn't see any benefit. The biggest benefit would seem to be tire choices but I'm very happy with 27" Pasela TGs. Having the rim and tire at a slightly larger radius would increase its moment of inertia and thus may make it accelerate a tiny bit less. Some people may be able to feel that. Since I'm not competing with anyone it doesn't matter to me. I'm about to start a new from-scratch build (details much later), but it will use 700c. Our '82 Peugeot tandem has 700c. So I'm not prejudiced either way.
As for the brakes fitting, do as GB says, just measure the extra reach available on the calipers.
A scientist, an engineer, and a mathematician were discussing bike wheels.
The scientist: Multiply the density of steel times the cross-sectional area of the spokes times the additional spoke length, times the number of spokes.
The engineer: Measure the weight of the two wheels.
The mathematician: Assume a spherical wheel...
Yes, measure it, and look at the second paragraph of my post (#8) for detailed instructions. It works like a charm.
Keep in mind, Campy NR brakes were made in two lengths: what we now call short or regular, and what we now call medium or long. The first category had reach up to about 48 mm, and the second had reach up to 59 or 61 mm. That means the middle-length ones are a match for the Weinmann 610s. If you need longer and you might, go to the Weinmann 750s, the Diacompe 750s, or Mafac racers. The 750s will reach about 75 mm and the Mafacs will reach about 71 mm. You can measure the reach of your Campy brakes by measuring with a ruler from the bottom of the brake shoe slot to the middle of the brake, on a line that's perpendicular to the brake shoe bolt. You'll have to eyeball the position of the brake bolt center, but that will be the reach. You might need to subtract a few millimeters to account for the fact that the bottom of the slot is not where the brake shoe center is.
And regarding the joke, none of your three wise men measured the geometry of the frame/rim/brake as a system. Strange!