Menu

Technical FAQ with Lennard Zinn: Follow-up to previous columns

  • By Lennard Zinn
  • Published Feb. 2, 2011
  • Updated Feb. 8, 2011 at 8:18 AM EDT

Re. Followup on centering Avid Shorty Ultimate cantilevers

Dear Lennard,
Here are a few comments on the centering problem:

First of all, the shop mechanic should have set them up with the narrow stance in front and the wide stance in back. The narrow stance, although counter-intuitive, offers more leverage/power, which is what you want. The wide stance on the other hand, reduces leverage and also gives more pad clearance from the rear rim, which is more likely than the front to get a wobble in the heat of battle. So win-win, since you want more power up front anyway.

As for the straddle moving when turning sharply, one way to solve this would be to use the old Avid Tri-Dangle straddle hangers which have the 2mm set screws to hold the hanger in place. The other option would be to use a hanger that could be crimped against the straddle wire to keep it in place like the old Shimano or Dia Compe.

If you don’t want to do that, use higher spring tension on both cantilever arms, which keeps them from getting bumped off center so easily. This should be used as a last resort since it should be fixable with comment #2 and this higher spring tension will decrease braking power for a given effort at the lever.
— Dave

A.Dear Dave,
Thanks for those suggestions.
To clarify why Dave says that the narrower stance (which is the way I run mine front and rear) is more powerful, look here at my earlier column.
— Lennard

Re.Dear Lennard,
I noticed the recent letter regarding Shorty Ultimates and the centering issue one reader had.

The response by Chris Shotwell and yourself mentioned ridding the brakes of any drag to correct the issue. One thing I did not see mentioned by Chris was the fact that the integrated bushings on the brakes themselves have been one of the causes of binding. I did notice that you said you filed them down because of issues with bosses on a new fork.

I experienced the same issue when installing them on my bike and remedied the problem the same way you did. Avid/SRAM has recently sent out a tech bulletin (to bike shops at least) regarding this issue. They are sending out, free of charge to bike shops, a retro-fit kit that includes new brake arms (left and right) and spacers to install on brake bosses that are either too short or too long (by 1mm) to prevent/remedy any binding.

I have just installed this kit myself and it has solved the problem. I found it highly unfortunate to have to file down a brand new set of brakes to make them work, but am pleased to see Avid has owned up to this issue and is offering a fix to mechanics and consumers who have invested in their product. Any customer with this issue should certainly be able to get help from their friendly local IBD.
— Tri Le
River City Bicycles

A.Dear Tri,
Indeed, SRAM has issued a Technical Bulletin on this and offers a replacement arm for the early-issued versions of the Shorty Ultimate to fit it on a 21mm brake pivot (the early ones were made only for 22mm pivots; current production fits both length bosses).
— Lennard

Re.Followup from TRP on the CX 9 V-brake :
Lennard,
1. We’ll have an inline barrel adjuster standard in the next iteration of the CX9
2. Some riders (e.g. Steve Tilford) have been using a Travel Agent/roll-a-majig) with the CX 9’s to increase lever throw and modulation. While I haven’t used this combination, I am curious to give it a whirl.

— Matt McNamara
TRP Marketing and Service Coordinator

Re. Regarding removing Campagnolo’s new PT cranks
Dear Lennard,

Plug: Use a small socket with a lip that fits securely into the PT fixing bolt (you could also use a strong washer or everyday socket extender). Campy sells an über expensive plug but it’s not needed — unless you have Campy fetish.

I have the plug and it wasn’t that expensive. I also use the same puller I use to pull off the UT bearings; I got mine from Cyclus.
— Peter Chisholm
Vecchio’s Bicicletteria

FILED UNDER: Bikes and Tech / Technical FAQ TAGS: / /

Lennard Zinn

Lennard Zinn

Our longtime technical writer joined VeloNews in 1987. He is also a framebuilder, a former U.S. National Team rider, and author of many bicycle books, including Zinn and the Art of Mountain Bike Maintenance and Zinn and the Art of Road Bike Maintenance, as well as Zinn and the Art of Triathlon Bikes and Zinn's Cycling Primer: Maintenance Tips and Skill Building for Cyclists. He holds a Bachelor’s degree in physics from Colorado College. Readers can send brief technical questions to Ask LZ.

Catch every stage of the Tour

Subscribe to the FREE VeloNews weekly newsletter