Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Recreational Cyclocross and Gravelbiking This has to be the most physically intense sport ever invented. It's high speed bicycle racing on a short off road course or riding the off pavement rides on gravel like :The Dirty Kanza". We also have a dedicated Racing forum for the Cyclocross Hard Core Racers.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 10-29-12, 08:03 PM   #1
nbo10
Junior Member
Thread Starter
 
Join Date: Apr 2012
Location: Ca
Bikes:
Posts: 24
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
front braking and vibrations

Hi all,
My wife surprised me with a new bike this past week! It's a 2012 cannondale superx. It's my first carbon fiber bike. It has a super nice ride compared to the hybrid I was ride. I've noticed that with moderate to heavy front braking bike develops bad vibration. The vibration gets worse when using a combination of rear and front brakes. No vibrations occur if using only the rear brakes. I've tested on various road surfaces so it's not the road. The vibration occurs at all speeds. It feels like the vibrations are coming from the bottom bracket. Any clues are to what is going on? Combination of EuroTRP/Mavic Kysrium Equipe wheels? I'm going to call the LBS tomorrow. But, would like some info before I talk with them.

Thanks
nbo10 is offline   Reply With Quote
Old 10-29-12, 08:55 PM   #2
pyze-guy
Yup
 
pyze-guy's Avatar
 
Join Date: Jan 2004
Location: where the sunbeams end and the starlight begins
Bikes: Kona Unit, planet X cx bike, khs fixed gear
Posts: 3,054
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Its the headtube mounted brake cable stop that is most likely causing the problem. Carbon forks seem to magnify the problem.
From Lennard Zinn

What happened is that the fork blades and your headtube flexed. Just a little but enough to change the distance between the brake cable stop and the brake arms. This caused the brakes to pull harder. Something had to give, either the tire will skid, the brake pad will skip, or you'll go over the bars and crash. In this case the brake pad skipped on the rim. That released the pressure momentarily the frame and fork flexed back then the pad caught again and the process repeateded. The whole process happens very quickly, many times a second.

Without a fork mounted cable stop there a limited option. Toe in the brake pad, use short pads. Check the canti brake sticky in the cx forum for more info/help.

I switched to mini v-brakes. Problem solved. Wasn't going to get rid on my ritchey wcs fork for one that has a fork mount.
__________________
When sadness fills my days
It's time to turn away
And then tomorrow's dreams
Become reality to me
pyze-guy is offline   Reply With Quote
Old 10-29-12, 09:47 PM   #3
nbo10
Junior Member
Thread Starter
 
Join Date: Apr 2012
Location: Ca
Bikes:
Posts: 24
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Ehh... I really didn't, or wouldn't, expect this type of problem with a new bike. How easy is it to toe-in canti brakes? I refuse to replace parts on a new bike.
nbo10 is offline   Reply With Quote
Old 10-29-12, 09:57 PM   #4
Shimagnolo
Senior Member
 
Shimagnolo's Avatar
 
Join Date: May 2008
Location: Zang's Spur, CO
Bikes:
Posts: 7,497
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 128 Post(s)
pyze-guy gave you the correct advice. Proper canti brakes use fork-mounted cable stops. Cable-stops mounted above the head tube are dangerous junk that are unsafe on anything over an 8% grade. In my case I learned the hard way that descending 14% grades with 200 pounds total weight resulted in an unusable front brake because it locked every time I touched it. Toe-in adjustment did nothing. Installation of a fork-mounted cable-stop solved the problem.
Shimagnolo is offline   Reply With Quote
Old 10-30-12, 05:18 AM   #5
flargle
Senior Member
 
Join Date: Jul 2007
Bikes:
Posts: 2,118
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Quote:
Originally Posted by nbo10 View Post
Ehh... I really didn't, or wouldn't, expect this type of problem with a new bike. How easy is it to toe-in canti brakes? I refuse to replace parts on a new bike.
Google "cantilever brake shudder".

The Super-X is a race bike built for performance, not for consumer convenience.
flargle is offline   Reply With Quote
Old 10-30-12, 06:59 PM   #6
bamacrazy
Senior Member
 
bamacrazy's Avatar
 
Join Date: Dec 2008
Location: Mobile, Alabama
Bikes: 05 Specialized Hardrock Pro, 87 Bianchi Axis
Posts: 201
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I had the same problem. I fixed it by placing a dime under the leading edge of each pad. I used a Velcro tie to hold the front brake lever. I then slightly loosened the break pad and re-tightened. What i was looking for was to ensure that the front edge of the pad did not dig in. Works perfectly, now.
bamacrazy is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 06:34 AM.