Centerpulls, what is old is new again
 

After reading another post about the fella with the broken Paul derailleur, I took a look at the Paul site.

Imagine my amazement on seeing their Racer centerpull brakes. Apparently they have some currency with the blingbling fixie crowd. (Says the guy with a DeBernardi trackie in the garage.)

Makes me wish for a mechanical engineer who can lay out the advantages of centerpulls old and new, and sidepulls old and new and dual pivot sidepulls. I know we have one out there; lay the effort arm talk on us.

I have two custom bikes which were built with mounting posts specifically to use those Paul's Racers.

They are great brakes.

I love them.

I think you will see a resurgence in centerpulls with all of the retro looking boutique bike coming out these days. I'm fond of them because you can use larger tires and they are easier to set up than cantis.

The Paul stuff is really nice and he is a nice guy as well (he is kinda local).

to me, center pulls have all of the best features of side pulls and cantilevers combined.

Calling Danno, we need a really detailed answer.

Are they the same as U-brake mounts? They sure look it. Just imagine putting a $100 brake on my $50 POS. :)

I love center pulls, easy to adjust and manage. I always run into trouble with single pivot.

I don't know if U Brake mounts would be positioned properly or not.

I know that Canti mounts are not.

If you want the Paul's Racers and you want the post mount, then you make that decision at the build stage as the posts are positioned differently.

I'm planning on using them whenever I build my custom tourer.
-Gene-

Gonna put my Mafac Racers on the 1966 Claud Butler tourer I plan to build next. Still not decided what to put the Mafac Competitions or many sets of Weinmann Vainquers onto though - maybe a gas pipe fixie?

I don't reckon you can beat modern dual pivots for stopping power, old GB side pulls for the antique look but centre pulls are great for classic tourers IMHO.

still, we need someone to stop in and actually compare the stopping power and efficiency of the different types

Centerpulls are the only correct choice for some bikes. :)

I put Mafac racer on my PX10 rebuild. They work as well as any dual pivot modern brake I've used. The Weinmann style center pulls on my Motobecane Grand Record, by contrast, are only functional (even with modern pads).

I'm pretty sure centerpulls are responsible for some of my hearing loss. ;)

The Bicycle Quarterly last issue but one was devoted to brakes. As you might expect from the "randonneuring" perspective of the editor, Jan Heine, there was a lot of attention devoted to Mafac cantilevers and centerpulls. Centerpulls on brazed-on posts were put forth as the high water mark for braking efficiency and light weight, I think.

don't know how you can beat cantis for weight. I like the fact that braze ons for centerpulls go closer to the crown, especially nowadays with lighter tubing.

I have a Ph.D. in Mechanical Engineering, but I'm too lazy to do an analysis. In the end, it comes down to how much force you are putting on the brake pad. The brake pads are very important. Also how much stiffness in the design. I suspect most brakes that aren't very good actually flex a lot and can't maintain the effective force they are putting on the brake pad. So it's a difficult question that probably isn't answered by some of the easier calculations I can think of.

These are showing up on some of the new super aero TT bikes

http://i47.photobucket.com/albums/f1...y90dollars.jpg

I have to say I am not really impressed with them and they aren't really centerpulls since the cable set up is like that of a V-brake but as you can see they have the basic centerpull design.

No offense but how is that front brake working? Did the builder have access to these brake when he made the bike? That bad angle looks really harsh.

http://www.bikeforums.net/attachment...1&d=1238523999

But it's not Shimano.

Indifferently,

-Lord Helmet
http://www.jaysmarine.com/darkhelmet.jpg
(Or else, what?)

I just had some old weinnmans red anodized along with a bunch of other parts, for the heck of it. The hand steel wool finishing paid off. :D I'll post some photos once i get them put back together.

BTW anyone know of a source for new straddle cables for those old Weinnmans?

Yup - check out the pics I took at the Tour of California Prologue in February. Note the front brakes. In the first pic, it is not rigged like a center pull, but sure looks like one. In the second pic, looks like the same caliper, but rigged as a center pull:

http://i162.photobucket.com/albums/t...OC/rider-2.jpg

http://i162.photobucket.com/albums/t...OC/rider-1.jpg

Same pics, cropped closer:

http://i162.photobucket.com/albums/t...OC/rider-3.jpg

http://i162.photobucket.com/albums/t.../TOC/rider.jpg

I think the old centerpulls and cheap side pulls suffered from two problems.

1. The arms flex out of plane - above the pivot point from cable tension, below the pivot point due to frictional forces at the spinning rim.

2. The pivot point bearings have a lot of slop in them. This adds a certain amount of deadband to their behavior and contributes to a mushy feeling and makes them slightly more difficult to control and modulate. To some extent, this is behaves like out of plane flex, but with a near zero springiness.

Arms need stiffness in plane as well as out of plane. Mafac Racers were thin and flexed out of plane WAAAY too much for my tastes.

The old Wienmanns, with their crappy pivot bearing were impossible to adjust out the deadband while maintaining a low friction bearing.

The Campanolo Nuovo Record and Shimano Dura Ace brakes were so much better!

I've never seen one of the Paul's on a fixed gear. The "blingbling fixie crowd" is not into brakes. I've seen them almost exclusively on randonneurs and passhunters.

Centrepull brakes fell out of favour because they required a lot more hardware to do the exact same thing as good sidepull brakes did. For the average person, they did have the advantage of being easier to keep centered than cheap sidepulls.

Centrepulls that require posts on the seat stays and forks are not the same thing as the old racing centrepulls. Again, a lot more hardware to do the same thing as cantilever brakes do.

So, there just isn't much point in using centrepull brakes, except maybe in situation where a person might need longer reach and more fender clearance. But there are sidepull brakes that do that now.

I have center pull Shimano Tourney on my road bike, and they work great - I dont' know physics, but they stop me every time.