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HELP: Is there an „ideal“ canti setup?(7 posts)

HELP: Is there an „ideal“ canti setup?anaerobic Max
Nov 19, 2003 2:47 PM
I have been following this forum for a couple of months and right now i'm building up my first CX rig. as i rather missed the age of cantis (i'm only 18) i'm having some sorta problems with setting up my cnc'd beauties. I hope you guys could help me by answering some questions and giving me hints on how to make my cantis work perfectly.

What is the best angle for the brake arms? Should i keep them rather low and push the brake pad holder towards the rim? This can be seen in the pic (the left brake arm). Mind that the right one would be turned closer to the rim if set up properly

What is the ideal length of the transverse cable? Keep it as short or as long as possible – or something in between?

And what about the yoke? Low or high?

My idea was like the following: brake arms turned to the outside as much as possible, the angle between the brake arm and the brake pad holder as big as possible, the brake pads pushed all the way to the rim and the yoke as high as possible.

My main issues are brake power, mud clearance and modulation. Should i try to find an average setup?

Thanks in advance!

Ps: pics and specs of my build will follow as soon as i got the missing parts (truvativ cranks, BB, stem and bar) – thanks to everybody
basic setup principles...damon
Nov 19, 2003 5:55 PM
Here are the quick and dirty basics:

1) Assuming your pads are set up right, i think it all comes down to the angle the straddle cable makes with the arms.
2) A low straddle cable = power, but also = "mushy" brake levers and little pad movement
3) Conversely, a high straddle cable will yield more pad travel, firmer feel at the levers, at the expense of power.

If you look at it in terms of a right triangle (remember your trigonometry?) with the hypotenuse as the straddle cable (the two sides of the triangle being a horizontal line drawn through the cable/brake arm intersection, and a vertical line corresponding to the main brake cable), you can visualize how having a low hanger (big horizontal, small vertical) makes lots of power at the expense of pad travel...

I'm not sure i'm explaining this clearly (as is often the case with being an engineer). But basically, if you realize that everything you are doing with the brake arm geometry is simply affecting that cable to brake arm geometry, you will be able to find a good compromise of brake feel, power, and clearance.

Good luck, and i'm sure someone a little more concise will come a long (at least i hope so! :-)

-Damon
Damn, that's prety good stuff!haystack
Nov 19, 2003 8:27 PM
Your explanation is better than you think and succinct. IMO, mushy brakes aren't a bad thing.

For even more lessons in geometry, trig and calculus, see the ever-wise Sheldon Brown for answers (or more confusion). Click here>> http://www.sheldonbrown.com/cantilever-adjustment.html and here http://www.sheldonbrown.com/cantilever-geometry.html.
Thanks, and excellent links - Sheldon is a freaky smart guy (nm)damon
Nov 20, 2003 12:47 AM
and yes, mushy brakes aren't bad... just to the point of rim clearance and levers not bottoming out against the bar.
basic setup principles...jsbx
Nov 19, 2003 11:51 PM
Damon the "Salmon Cruncher" forgot to mention that brake levers can also affect feel: newer levers are sprung, older non-aero types are not...
with the longer arm CNC style brakesatpjunkie
Nov 21, 2003 2:27 PM
you don't need to run the arms so far 'out'. I ran the old Paul CNC's with the arms at about 20 degrees from vert. yours are set at what looks like 45. Though this will work it negates the design of this brake to provide adequate power while not being as obtrusive as older style canti's. This modern style CNC'd canti... Paul , Onza, Avid Tri Align... is supposed to be more flush with the fork and more importantly the seat stays so you don't catch your leg on mounts and dismounts as much as the older style (Paul Neo Retro, Frogglegg, Spooky, Mafac...)
hope this helps and doesn't further confuse the issue.
with the longer arm CNC style brakesanaerobic Max
Nov 22, 2003 1:11 PM
thanks atp!

I changed my setup, and will post a pic tomorrow....