[CR]Centerpulls (Deltas)

(Example: Framebuilding:Technology)

Date: Fri, 18 Jan 2008 09:15:21 -0800 (PST)
From: "Tom Dalton" <tom_s_dalton@yahoo.com>
To: jerrymoos@sbcglobal.net, Classic Rendezvous <classicrendezvous@bikelist.org>
Subject: [CR]Centerpulls (Deltas)

When I used 23c Contis with my Deltas, they didn't clear the underside of the caliper until I moved the pads to the very bottom of their very limited adjustment range, and then moved the entire caliper up, within it's broad adjustment range, to compensate. But here's the thing about Deltas... they are not suitable for a wide range of applications. They are for racing bikes so they really should not be expected to be compatible with 32mm tires. They are for racing, and the expectation is that a pro mechanic will work on them... So, unrealistic as this expectation might be in a world where weekend warriors want the most expensive racing gear available, complaints that Deltas require a lot of tinkering and maintenance don't really mean a lot to me. It's like buying a Porsche GT and then complaining that CF brake rotors don't work well in when cold and cost too much to replace. Deltas are for racing bikes, so if they are better suited to modulating speed through corners than panic stopping in city traffic. And actually... the one time I did panic brake in a race using Deltas, I put a big flat spot in my nearly new CG, so they aren't totally unable to exert braking force... nor did they compensate for my error.

Anyway, Deltas are not the greatest brakes ever and they were just "too much" in many respects. They were heavy and expensive and all that weight and expense was in an effort to improve modulation, and to look different and possibly be-sorta-kinda to be aero. While the fact that many pros of the era stuck with Cobaltos (Record/Super Record caliper) until the dual pivots came out is telling, many pros did choose them and they simply aren't as stupid and crappy as many people want to believe. I think the bad rap comes from the fact that they were hard to set up. Most Deltas that I've played with on other people's bikes are just really badly set up. The big issue is that the geometry has to be right so that the internals are in the right part of their range of motion. The pad spacing sometimes needs to be tweeked to compensate for rim width, and even pad wear. Also, there are two basic versions of the brake (and many smaller variations) and a few different levers, and I can only say that the later ones were quite usable in the limited application of racing bikes with skinny tires.

jerrry wrote

Actually, the Delta has an adjustable drop, so to the extent that the clearance problem is one caused by fork geometry, the brake drop can usually be adjusted to resolve that. However, it is true that there is a limit to the rim plus tire height that can be accomodated by the distance between the bottom of the caliper its center and the brake pads positoned at the bottoms of the slots. I run 23 mm tires with room to spare, and it looks like 25 mm would work, but larger than that might be a problem.

Regards,

Jerry Moos Big Spring, TX

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