[CR]Re: Treatise on Campy Delta Brakes

(Example: Production Builders:Cinelli)

Date: Thu, 14 Mar 2002 11:00:57 -0800 (PST)
From: "Tom Dalton" <tom_s_dalton@yahoo.com>
To: wspokes@penn.com
Cc: classicrendezvous@bikelist.org
In-Reply-To: <Springmail.105.1016131877.0.09376700@www.springmail.com>
Subject: [CR]Re: Treatise on Campy Delta Brakes

Tom

How do you really feel about them though?

Actually, in some way my long-winded post may have not accurately expressed my views of those things. Obviously I think they are over-engineered and finicky and generally offer no benefit over simpler designs. However, they are just over-the-top enough to be kinda cool. And they are certainly good looking, at least in the context of C-record equipped bikes... And I LIKE working on bikes, so I don't mind the extra effort. A labor of love.

Walt

Tom Dalton wrote:
>

Since the original Deltas hit the market in 1985, technically we are on topic, though philosophically we may be way off...

My feeling is that Deltas got a bad rap for two main reasons:

1) The early ones weren't any good. The very first generation (ultra rare, never seen a pair myself) was so bad that Campy had to recall them. I had always heard that they just didn't apply enough force at the rim (low mechanical advantage) but more recently I heard there was a problem with corrosion in the linkage (later made with stainless). When they returned to the market they were better, but still under-powered. While many Campy-equipped pros stuck with Cobaltos (SR's) at this time many others used the Deltas. Within teams it was a mix, so presumably some people actually chose the Deltas. They were said to be better speed modulators. Anyway, it took too long for Campy to get the Delta sorted out. It was well over a year between the recall and the second-gen. model. It wasn't until the 1991-ish fourth gen. model with the crossed over linkage and more compact body (cover plates don't interchange!!!) that they really worked well. Almost as much power as an SR bu! t now way behind the new Shimano dual pivots! It should have been seen as a bad omen that the only C-record part that Campy protoyped in the peloton was the retrofriction shifter (disguised as SR). This is really lame considering that SR, for example, was not on the market until well after the pros were using (testing) it. Shimano 8-speed, STI, and dual pivots were all prototyped and used by some pros, before being introduced. What was Campy thinking?

2) Deltas are really hard to set up. In a world were many mechanics can't properly set up a sidepull, and most can't set up cantis, Deltas were waaaaay too finicky. The vast majority of Delta's I've seen on built-up bikes were set up quite badly. Campy's areo levers are pretty unforgiving of poor cable preparation (contrast w/ brand S) and many Delta setups have a ton of cable problems. Use the correct ferrules, clear out housing burrs, restore the liner shape with a tapered punch before installing the wire. Lube with oil, not grease (too sluggish, esp. in cold). Late-gen. Deltas came with nice housing liners that had a trumpet-shaped opening. Like the directions say, trim things from the other end (which will be the caliper end). The later ferrules had bigger openings which, when combined with the trumpet-shaped liners, made for a smoother path for the wire as it entered the housing. Amazing how Shimano gets it all right without any ferrules, simply by having a de! ep seat for the housing.

Housing lengths and routings are critical. Excess housing above the caliper will loop sideways and the oblique cable path will push the linkage out of alignment making the caliper asymmetrical (ugly) and screwing up the centering on the rim (actual problem). Cut things too short and the housing can't push down on the adjuster like it should. Properly set up, the wire pulls up at the bottom of the linkage while the housing pushes down on the adjuster, which is connected via a hollow threaded shaft to the top of the linkage. It is important that the adjuster is backed out enough that the housing end doesn't bottom on the treaded shaft. Otherwise the cable goes slack when the lever is released and there is wasted lever travel as the brake is applied.

On an SR caliper you bolt it to the frame and set the pad height and rotation relative to the rim. On Deltas, you need to get the correct pad angle relative to the sidewall at the same time as you set the shoe height near the middle of the very short adjustment slot. Then you get the pad height correct by moving the caliper up and down on the mounting bolt. Make sure you end up with enough tire clearance. If you have a HUGE tire, like a 23c Conti (which is not really huge at all) you will need to set the pad at the very bottom of the slot and raise the caliper. The result isn't too pretty. Forget any tire larger than about 23mm. If your tire clears when new, don't expect this to be the situation after the casing stretches a bit. While you're doing all the gymnastics with the heights and pad angles, you also need to mind the rotation relative the rim curvature and the toe in (on later models). With four adjustments locked in by the brakeshoe locknut, it takes many t! ries and an ability to eventually decide that it is "good enough." By all means be certain that the caliper height is correct before you go through all the iterations on the pad setup. When the toe-in is lost to pad wear the brakes will squeal, so you need to occasionally tighten the little setscrews that shove the pad out of the holder. Despite what it says on "Campy Only" these setscrews contact the rubber directly, mashing one end of the pad or the other toward the rim. At the tail end of Delta production they came with bigger pads (taller, didn't taper toward the rim) that provided a few extra square millimeters of rim contact. Take all you can get. Getting good rim contact through precise alignment will be awarded by near NR/SR level of braking power. All that extra weight, expense and setup time will get you up to circa 1969 standards of Campy braking prowess.

All of the Deltas I've seen, including my last-gen set, require a 3.5 mm Allen to clamp the cable. Bhondus makes one, and machinist supply companies sell them. Conveniently, Sears includes 1.5, 2.5, 4.5, and 5.5 millimeter Allens with their nice $20 sets. No 3.5 mm! And forget about reusing any cable that has been clamped by that damn setscrew. They fray, and will not go back into the housing or caliper once removed. I tried soldering, but to no avail. You're best off cutting the wire as short as possible to avoid interference within that crowded caliper. Do all the initial setup with a some excess wire and once things are right, determine the exact wire length you will need to have only a millimeter or two of excess, and mark it with a marker. Pull the wire from the caliper, cut it cleanly with a cable cutter and reassemble. Hold the area around the setscrew with a 9mm wrench as you tighten. With the wire cut short, it will fray as soon as you clamp down on it. ! Don’t try to cut the wire after clamping it; your cutter won’t reach in far enough to get a clean cut and all the frayed ends can rub on other parts of the mechanism.

Oh yeah, on the third gen models you need to set the Powergrade setting at the lever. Go to max mechanical advantage. AND ANOTHER THING... Not only do the calipers accommodate a narrow range of tire profiles, they are also fussy about rim widths. For best mechanical advantage, you want the linkage pretty compressed before the pads hit the rim so a too-wide rim can lower your braking power. On the other hand, modern rims (sub GP-4 width) force the linkage to compress too much, and potentially, to bottom out. Needless to say, it is a problem when the caliper reaches the end of its travel at a time when you would really like the pad to keep going toward the rim. There are two widths of pad spacer for the later models that allow for some adjustment.

The whole idea with this brake is that it has low mechanical advantage, and therefore more shoe movement per unit lever travel, during the initial compression of the linkage, followed by increasing mechanical advantage as you need it. Properly adjusted, the pad will sit well off the rim. I realize that everyone has his/her preference on the "tightness of brakes" but most Deltas I've seen are simply too tight. Just because your SRs are set with the pad 3mm from the rim, doesn't mean your Deltas should be. Go by where you want the lever, relative to the bar, when the pad hits the rim. That having been said, I'm biased toward running Deltas really loose, where I can pull the lever almost all the way to the bar with a bit of force. This way I have a good grip on the lever when I really need to crank on it, which, with this brake, is pretty often. Finally, disregard anything you're told about running Deltas loose to get the caliper further into its high-mechanical advant! age phase. The mechanical advantage changes with linkage compression, which is determined by rim width, choice of spacer, and pad wear. On the other hand, I think that due to the relative positions of the pivot, cable hanger and cable path, the levers may give more leverage further along in their arc. I think this is the reason people feel better leverage when the brake is run loose.

That’s “all” I have to say on this matter.

Tom Dalton

Bethlehem, PA

wspokes@penn.com wrote: Garth
> I believe a quick explanation for Campy delta BRAKES is that fact they were commonly referred to in the racing crowd as "speed adjusters".
>
> Walt Skrzypek
> Falls Creek, Pa
>
>
> garth libre wrote:
> > So much on a bike is simplicity defined, but those Delta brakes look like something off a Ferrari. They seem to be a different system from the Shimano Dura Ace AX brakes. It's hard from looking at the pictures to know how these things worked. Is it some kind of lever cam action or pivoting solid metal center wire substitute?. Without having seen these things in action, it's hard to imagine what was the physics behind them. Garth Libre in Surfside Fl.
>
>
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