Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

confuzed about direct vs indirect calipers

Notices
Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

confuzed about direct vs indirect calipers

Old 03-05-10, 03:09 PM
  #1  
chico1st
30mi/day commuter
Thread Starter
 
Join Date: Apr 2008
Location: Toronto, Canada
Posts: 797
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
confuzed about direct vs indirect calipers

ok on sheldon site it says this
Conventional brake levers used with direct-pull cantilevers will usually not pull enough cable to stop in wet conditions without bottoming out against the handlebars. In dry conditions, they either won't work, or will grab too suddenly.
Direct-pull brake levers used with any other type of brakes will feel nice and solid when you squeeze them, but due to their lower mechanical advantage you'll need to squeeze twice as hard to stop as you should, so unless you are a lightweight rider with gorilla-like paws, this combination isn't safe either.
now it makes sense that Vbrake levers pull less cable, but then how does the first statement make sense. Wouldnt long-pull levers used on a vbrake make it stop super fast.
chico1st is offline  
Old 03-05-10, 03:33 PM
  #2  
desconhecido 
Senior Member
 
Join Date: Mar 2010
Posts: 1,781
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 395 Post(s)
Liked 118 Times in 93 Posts
Ok. V-brakes, what Sheldon was referring to a "direct-pull cantilevers" require about twice as much cable travel to cause the brake pads to get the same amount closer together as compared to center-pull cantilever brakes, or caliper brakes for that matter. This means that for a given distance of lever travel, you need to pull about twice as much cable with a V-brake as with a center-pull cantilever.. Full lever travel with a lever designed for center-pull brakes will not pull enough cable to cause V-brakes to grip tightly. The opposite is true -- levers designed for V-brakes pull too much cable when used with center-pull cantilevers. Remember mechanical advantage -- you trade force for distance or visa versa. So, if you use V-brake levers with center-pull brakes, you get less distance* but have to apply more force. Sheldon thought too much force and he was probably right, as he almost always was.

edit:
* less distance in lever travel for the same cable travel is what I meant. Less lever travel for the same cable travel requires more force on the lever.

Last edited by desconhecido; 03-05-10 at 03:41 PM.
desconhecido is offline  
Old 03-05-10, 03:34 PM
  #3  
LarDasse74
Guest
 
Join Date: Jul 2008
Location: Grid Reference, SK
Posts: 3,768

Bikes: I never learned to ride a bike. It is my deepest shame.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by chico1st View Post
ok on sheldon site it says this


now it makes sense that Vbrake levers pull less cable, but then how does the first statement make sense. Wouldnt long-pull levers used on a vbrake make it stop super fast.

V brake levers (direct-pull cantilevers) need more cable pull. More cable pull = less cable force.
LarDasse74 is offline  
Old 03-05-10, 03:43 PM
  #4  
chico1st
30mi/day commuter
Thread Starter
 
Join Date: Apr 2008
Location: Toronto, Canada
Posts: 797
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
i find mechanical advantage confusing
but ok ... i think i have normal levers on a v-brake garage sale bike i just got, i adjusted the brakes well but still have to pull the levers all the way in to stop the bike, which seemed too far... now it all makes sense.

since everyone seems to like v-brakes better than calipers i guess ill change the levers.
chico1st is offline  
Old 03-05-10, 04:05 PM
  #5  
dabac
Senior Member
 
Join Date: Mar 2008
Posts: 8,219
Mentioned: 43 Post(s)
Tagged: 0 Thread(s)
Quoted: 928 Post(s)
Liked 93 Times in 71 Posts
Originally Posted by chico1st View Post
now it makes sense that Vbrake levers pull less cable...
No, the other way around V-brake levers pull more cable for a given amount of lever travel.

Originally Posted by chico1st View Post
Wouldnt long-pull levers used on a vbrake make it stop super fast.
Long pull levers on a long pull brake is a matched combo, and stops as could be expected. Short pull levers on long pull brakes gives excellent braking power, but also usually trouble with getting the pads to clear the rim when relaxed and still close enough before the levers bottoming out. I've used it on front brakes occasionally, where it works rather well. For the rear it's usually too much slop in the system to acheve a "clean" setup.
I've never found the supposed lack of modulation any trouble, it's still far less than the difference you get while riding in rain, or switching between bikes.
dabac is offline  
Old 03-05-10, 04:25 PM
  #6  
desconhecido 
Senior Member
 
Join Date: Mar 2010
Posts: 1,781
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 395 Post(s)
Liked 118 Times in 93 Posts
Mechanical advantage is really pretty simple, but if you've never thought about it, it might be confusing. Just remember what some old dead guy said, with a long enough lever, you can move the world.

If you want to use V-brakes then you need levers designed for V-brakes or a little gizmo called the "travel agent". I have a bike with a front V-brake and Campy break levers (designed for caliper brakes). To make that combo work, I've got a travel agent mounted to the V-brake and it works perfectly. Google for the travel agent and you'll find a bunch of info. Some are for sale through Amazon (where America shops).
desconhecido is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Needles
Bicycle Mechanics
8
08-07-19 07:19 PM
AlanHK
Bicycle Mechanics
5
09-03-13 05:01 AM
leob1
Bicycle Mechanics
10
06-20-12 01:51 PM
wearyourtruth
Bicycle Mechanics
6
12-10-10 03:46 AM

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


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.