Sunday, April 5, 2015

Velo Orange Grand Cru Zeste Brakes Review

I've been struggling to find cantilever brakes strong enough to satisfy my needs. The very rainy Severna Park 200k ride demonstrated that a few hours of rain, road oil and grit can turn adequate brakes into non-stoppers very quickly. After way more research than I thought possible on the subject of cantilever brakes, I got the Velo Orange Grand Cru Zeste brakes. I figured the longer arms plus the low profile should give me the most stopping power available from a cantilever brake.

While researching cantilever brakes, I relied mostly on this mechanical analysis from Circle A Cycles. I also read Sheldon Brown's article on cantilever geometry, but I found it oversimplified things and left out a lot of details. I did not completely verify the math in the Circle A Cycles article, but I will trust the resulting equations. Namely, the equation relating mechanical advantage (MA) to yoke height (footnote 8 on page 3, his equation uses degrees, mine uses radians).


For a given bike, PO is fixed at half the distance between the cantilever bosses, and DO is the vertical distance from the cantilever boss to the middle of the rim braking surface. The variables are PA, the distance between the cantilever post (P) and the cable anchor point (A), YO, the vertical distance from the cantilever boss to the yoke, and 'a', the cantilever angle, the angle from vertical of the line PA. This angle is measured differently than in Sheldon's analysis, where it is the included angle between the A, P, and the rim surface.

Circle A Cycles diagram. Cantilever Angle is APZ (not APR as in Sheldon's).


Sheldon's Diagram. Cantilever Angle is angle APS.
The equation is far from elegant, but it is easy to see that lengthening the arm of the cantilever brake will increase the mechanical advantage. And it doesn't take much, if DO=24, PO=44 (in mm), and a=.436 rads (25 degrees), then a 10% increase in the arm length (PA) leads to a 30% increase in MA. If your canti bosses are higher than normal and DO is smaller, so that the pads are in the lower end of the adjustment range, the MA can be increased 15-25% over pads at the upper end of the adjustment range.

For reference here is a list of a few cantilever brakes and their arm length (PA, pivot to cable anchor distance, measured 'as the crow flies'):


Brake NameArm Length (PA) in mm'a' angle (approx)
Velo Orange Zeste
7615
Paul touring
6820
Shimano Non-series
6720
IRD CAFAM I
6730
Avid Shorty Ult
6375 or 30
Tektro Oryx
6030
Paul Neo Retro
4774
Tektro 720
4875

There are threads started every day on how to adjust cantilever brakes, and given that I've used four different sets on my rear brake (Tektro CR720, Shimano non-series low profile, generic low profile, and VO Zeste), here's what you need to know.

  • lower yoke height=more power (but less modulation)
  • medium and wide profile brakes are less sensitive to yoke height, up to a point
  • low profile brakes are sensitive to yoke height throughout the range
This is relatively common knowledge, the part most people don't realize is there is tipping point for wide profile brakes (like Tektro CR720). Lowering the yoke height doesn't make them much more powerful, until you reach a certain point. Then the mechanical advantage skyrockets with each small lowering of the yoke. Perhaps all the people who are satisfied with the CR720's have sufficiently narrow tires or other frame distances that allow them to have a lower yoke height and thus higher than normal mechanical advantage. It's also possible that different levers have sufficiently different mechanical advantages (while still being 'short pull'), that the 720's can perform well. TRP makes two versions of the mini-V brakes with different length arms (and thus different mechanical advantages) for Shimano/Campy and SRAM brake levers, respectively.

Enough with the engineering, onto the review.

Comes with two brakesets, enough for one bike. All necessary hardware? Yes. Instructions? No, none at all. Tools necessary: 2, 2.5, 3, 4, 5 mm allen keys, 10 and 13mm wrenches, phillips screwdriver.

When installing the calipers, the 5mm allen key bolt should be facing out, and the 13mm nut should be behind the caliper. The 13mm nut has to be very tight to keep the brake pad holder from moving. It would be easy enough to label the bags of hardware 'front' and 'rear.' But they weren't.

There are so many adjustments that can be made it can be time consuming to go back and forth between various adjustments until the pads hit the rim squarely, at the same time, and all adjusting bolts  (spring tension, pad angle, cable barrel adjuster, etc.) are near the middle of their respective adjustment ranges.

These take more tools to install than are present on any multi tool I have ever used. It is a little bewildering that a brake that may be used for long distance events would require either a 13mm wrench or an adjustable wrench.

I certainly appreciate the long arms that provide more power than almost any other cantilever brakes, but the user interface (to borrow a software term) is not quite refined enough to be truly useable for non-mechanics. These brakes could really use a couple hundred more hours of engineering. I would have considered halting the project once a 13mm wrench was required. It is unfortunate that Velo Orange is such a small company they can't afford to make these more user friendly without making them prohibitively expensive. As a comparison, Compass Bicycles offers boutique centerpull brakes that are as powerful as possible with no performance compromises (they also directly copied a well established design, so they spent a lot of time on manufacturing, not as much on design). But they require specialized bosses that are so sensitive to alignment and spacing, they should only be installed by a framebuilder. They also cost $325 for one bike.

Update: In corresponding with smutpedaller about these brakes, they pointed out that they are available here under a different name, although the listed arm length is significantly different (66mm vs. 76mm) than the Velo Orange ones. After a careful analysis of the product photos with some calipers and using the length of the brake shoes as a constant (54.2mm actual, 26.5mm in the photos), it seems the product description is correct, they are indeed shorter than the Velo Orange Zeste brakes. Perhaps the only thing VO did was spec the arm length and the brake pads.





The brake pads sit far enough away from the frame that the entire arm swings out of the way for removal of fat tired wheels. It's a nice feature, and Grant can tell you all about it.

I swapped out the stock pads for Kool Stop Salmons. Once installed the brakes work great. Fantastic power with good modulation. The Compass 650Bx42mm tires have so much grip you are still unlikely to lock up the wheels. I could stop the bike with one or two fingers on the front brake. On a drop bar lever, that is pretty impressive. Pads run pretty close to the rim for cantilevers, about the same as V-brakes.

After using Kool Stop pads for about 8 months, they developed a horrible squeal in both brakes. I switched to the Velo Orange stock pads, which are supposed to be resistant to squealing. They were quieter, but also not nearly as powerful. I put up with it for two more months until they started squealing as well. The pad holders don't allow you to toe the pads in very much, so I wasn't able to eliminate the squealing that way. I finally gave up and switched to a linear pull V-brake with a Travel Agent in the rear. I couldn't do this in the front because of too little clearance between the front rack and the fender, so I am switching to the Tektro Oryx calipers. They won't be as powerful, but hopefully they will be silent.

So, after 1 year, I had to abandon both Velo Orange brakes due to squealing issues. It's possible it is partly an issue with the rim, but I don't have a spare wheel I can try I haven't been able to eliminate this cause.


Cable Pinch Bolt (Sturmey-Archer on left, Velo Orange on right)

There were only two reviews of these brakes I could find online. One mentioned that the pinch bolt was prone to cutting the straddle cable since the end of the bolt can be sharp. I checked out the bolt and it seemed fine. I have been using the Sturmey-Archer pinch bolt of a similar design for years on my drum brakes without problem. The S-A pinch bolt uses larger diameter threads, but is functionally identical. If you aren't used to these types of anchors, they actually deform the cable instead of the clamping it. You do not need to tighten as much as normal anchor points where the cable is clamped between a washer and the arm. If I had to guess, I would use 5Nm.

If you go the V-O webpage on these brakes, here. You will notice that the brake cable exits the pinch bolt on both sides at a strange angle. Whoever installed it didn't hold the anchor with a 10mm wrench while tightening the M4 bolt. Please do not follow their example.


By the numbers:
Power: 5/5; Ease of installation 3/5; Field Serviceable: 1/5

1 comment:

David Henri said...

How can you blame the brakes for squealing when it's the brake pads! Just swap out the pads. The mechanical brake itself has nothing to do with the squealing.