More Brakes

On 12/11/2015 11:14 PM, Doug Landau wrote:
On Friday, December 11, 2015 at 4:44:29 PM UTC-8, Sir Ridesalot wrote:
On Friday, December 11, 2015 at 7:27:36 PM UTC-5, Frank Krygowski wrote:
On 12/11/2015 6:56 PM, Sir Ridesalot wrote:
On Friday, December 11, 2015 at 6:44:55 PM UTC-5, Frank Krygowski wrote:
On 12/11/2015 5:18 PM, wrote:
I took my cross bike out on a reasonably difficult ride on Tuesday and discovered that my cantilever brakes operated OK but took the forearms of Arnold Schwartzennegger to operate. While I suppose my strength would build up over time, I have to particular desire to try and do this on a hard ride if a medium ride was this difficult.

To get to the point - are linear pull brakes superior?

I'd say it depends on your criteria. I think linear pull brakes are
easier to set up; and they don't require a cable stop on the frame, so
they're easier to put on suspended mountain bike forks.

Standard cantilevers are more versatile. If you know what you're doing,
you can adjust cantilevers to require greater or lesser hand strength.
Here's an article on that:
http://sheldonbrown.com/cantilever-geometry.html

The basics come down to this: The shorter the straddle cable, the more
mechanical advantage the cantilevers will have. That means less hand
strength is necessary at the levers. It's what I've done with our
tandem, and it works great. Balancing that advantage, you'll have to
keep your wheels more accurately in true to prevent scraping.

If it really requires super hand strength to operate your brakes, I'd
think something else is wrong. Maybe you could give us more details: Is
the bike new? What model? What brake levers? Are the cantilevers the
classic L-shape, or the newer "low profile" shape?

Regarding potential problems: Do the brake shoes need to be replaced?
(Try Kool-Stop Salmon.) Do the cables need to be lubricated or replaced?
Are the cables well aligned, or is there a chance the inner wire is
scraping around some sharp corner? Is there any interference of moving
parts?

--
- Frank Krygowski

Friends of mine went from properly set up and adjusted cantilever brakes to linear sidepull brakes (aka V-brakes) and noticed a HUGE INCREASE in stopping power with a lot less hand force required. You can't get a much shorter straddle cable than the short length of exposed cable on a linear sidepull brake.

The part about the short length of straddle cable does not apply to
direct pull brakes (AKA V-brakes). That mechanism and its mechanical
advantage are completely different.


--
- Frank Krygowski

I know that. However the very short cable between the two arms of the linear pull brake calipers IS a lot shorter than ant on a cantilever and that helps to make the action feel more positive since there's no transverse cable or long length of cable getting compressed like there is on a cantilever brake set up. If the arms of a cantilever brake caliper could be made to be more vertical like a linear pull brake the braking of the cantilever brake would be much more positive too. I've done exactly that with some old style cantlever brakes that have long arms that are normally 90 dgrees to the rim. Moving the pads so that those arms are as close to vertical as possible makes a huge difference in the performance of the cantilever brake.

Cheers

Since the cable is coming from the center at a 45 degree angle, should the arm of the cantilever not also be at a 45 degree angle for maximum power?


Ideally, the transverse is a 90 degree (2x45) form, easily
checked with a piece of paper held in front of the brake, as
the pads touch the rim. The cable end points ( anchor or
cable head or whatever) want to be outside of a vertical
line through the brake pivot. If set up with those points
over center, the brake action goes all to hell. This is
common where the pads are pushed all the way out against the
arms (either on purpose or because the brake shoe hardware
isn't tight). Regarding cantilever brake shoes, most designs
allow more freedom of adjustment which seems to perplex a
lot of assemblers who have not looked at the pictures in the
directions, I assume.

Oh, and as Frank notes, the wires ought to be free of kinks.
Like classic British steel sidepulls, the brake arms should
return equally and that adjustment is best done by balancing
spring tension not by mangling the equipment.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On 12/12/2015 13:51, AMuzi wrote:

Ideally, the transverse is a 90 degree (2x45) form, easily checked with
a piece of paper held in front of the brake, as the pads touch the rim.
The cable end points ( anchor or cable head or whatever) want to be
outside of a vertical line through the brake pivot. If set up with those
points over center, the brake action goes all to hell. This is common
where the pads are pushed all the way out against the arms (either on
purpose or because the brake shoe hardware isn't tight).

That confused me a bit, but I think I've parsed it now - is your "pushed
all the way out against the arms" my "pushed all the way into the arms"?

Ie no space between the arm and the pad, and the post sticking out on
the other side.

On Friday, December 11, 2015 at 3:44:55 PM UTC-8, Frank Krygowski wrote:
On 12/11/2015 5:18 PM, wrote:

To get to the point - are linear pull brakes superior?

If it really requires super hand strength to operate your brakes, I'd
think something else is wrong. Maybe you could give us more details: Is
the bike new? What model? What brake levers? Are the cantilevers the
classic L-shape, or the newer "low profile" shape?

Regarding potential problems: Do the brake shoes need to be replaced?
(Try Kool-Stop Salmon.) Do the cables need to be lubricated or replaced?
Are the cables well aligned, or is there a chance the inner wire is
scraping around some sharp corner? Is there any interference of moving
parts?

Sorry about the delay, lots of home improvements to get through.

The bike is a Ridley XBow. The brakes are Shimano BR-R550's. The levers are Shimano 6800 105 with the internal cables.

I'm using the "F" spreaders that come with the brakes.

I've tried all of these things before but since recovering from my concussion after two and a half years I can't remember these things.

Now I'm sure I could improve the brakes marginally with softer pads I don't know if it would be significant enough to bother with.

Also it appears to me that the "racing" cantilevers are mainly designed to do nothing more than reduce weight. The levers are more perpendicular to the cable but the "Y" in the cable is longer. Does this balance out or actually lighten the brake loads?

I'm not kidding about how much muscle strength it requires to operate. So much that it makes steep downhills dangerous on the bike.

On Sunday, December 13, 2015 at 10:41:23 AM UTC-5, wrote:
On Friday, December 11, 2015 at 3:44:55 PM UTC-8, Frank Krygowski wrote:
On 12/11/2015 5:18 PM, wrote:

To get to the point - are linear pull brakes superior?

If it really requires super hand strength to operate your brakes, I'd
think something else is wrong. Maybe you could give us more details: Is
the bike new? What model? What brake levers? Are the cantilevers the
classic L-shape, or the newer "low profile" shape?

Regarding potential problems: Do the brake shoes need to be replaced?
(Try Kool-Stop Salmon.) Do the cables need to be lubricated or replaced?
Are the cables well aligned, or is there a chance the inner wire is
scraping around some sharp corner? Is there any interference of moving
parts?

Sorry about the delay, lots of home improvements to get through.

The bike is a Ridley XBow. The brakes are Shimano BR-R550's. The levers are Shimano 6800 105 with the internal cables.

I'm using the "F" spreaders that come with the brakes.

I've tried all of these things before but since recovering from my concussion after two and a half years I can't remember these things.

Now I'm sure I could improve the brakes marginally with softer pads I don't know if it would be significant enough to bother with.

Also it appears to me that the "racing" cantilevers are mainly designed to do nothing more than reduce weight. The levers are more perpendicular to the cable but the "Y" in the cable is longer. Does this balance out or actually lighten the brake loads?

I'm not kidding about how much muscle strength it requires to operate. So much that it makes steep downhills dangerous on the bike.

A link to a closeup image of your brakes front and rear would be a big help in diagnosing the problem.

Remember that if you do go to linear pull brakers aka V-brakes you'll need an adapter like a Travel Agent in order to use your 105 brake levers.

Cheers

On 13/12/2015 15:54, Sir Ridesalot wrote:

Remember that if you do go to linear pull brakers aka V-brakes you'll need an adapter like a Travel Agent in order to use your 105 brake levers.

Though if you are meticulous about maintenance and keeping your wheels
true, you can run Vs off road brake levers and they will be very
powerful. But they will need a lot of care - they'd need to be run very
close to the rims.

On Friday, December 11, 2015 at 5:45:24 PM UTC-8, Frank Krygowski wrote:
On 12/11/2015 7:44 PM, Sir Ridesalot wrote:
On Friday, December 11, 2015 at 7:27:36 PM UTC-5, Frank Krygowski wrote:

The part about the short length of straddle cable does not apply to
direct pull brakes (AKA V-brakes). That mechanism and its mechanical
advantage are completely different.


--
- Frank Krygowski

I know that. However the very short cable between the two arms of the linear pull brake calipers IS a lot shorter than ant on a cantilever and that helps to make the action feel more positive since there's no transverse cable or long length of cable getting compressed like there is on a cantilever brake set up. If the arms of a cantilever brake caliper could be made to be more vertical like a linear pull brake the braking of the cantilever brake would be much more positive too. I've done exactly that with some old style cantlever brakes that have long arms that are normally 90 dgrees to the rim. Moving the pads so that those arms are as close to vertical as possible makes a huge difference in the performance of the cantilever brake.

Sorry, but the transverse cable of a cantilever doesn't get "compressed"
at all. It's in tension. And it stretches only negligibly.

I have noticed that lots of cantilever brakes are set up with a bend in
the free span of the straddle cable. You can see a bit of that in the
bottom photo at http://sheldonbrown.com/cantilever-geometry.html as
opposed to the perfectly straight line as in Sheldon's top sketch at
that same page. Those bends do waste some lever motion as they
straighten out under tension, but that's not really stretching of that
cable in the usual sense. (I pre-bend mine around the saddle, so they
run in straight lines to the brake arms. It helps.)

I suppose we could get into a technical discussion about what affects
the performance of cantilever brakes. I'd say a prerequisite would be
to read and understand Sheldon's article. Then be prepared for some
equilibrium calculations - you know, free body diagrams, summing forces,
summing moments, all that.

Frank, in Sheldon's discussion of the U-brake it sort of hit a spot. As you apply the Cantilevers the angle between the actuation cable and the brake reduces thereby causing successively lower mechanical advantage. And that is what my problem felt like.

V-brakes do not have this change in leverage.

On 12/13/2015 10:54 AM, Sir Ridesalot wrote:
On Sunday, December 13, 2015 at 10:41:23 AM UTC-5, wrote:
On Friday, December 11, 2015 at 3:44:55 PM UTC-8, Frank Krygowski wrote:
On 12/11/2015 5:18 PM, wrote:

To get to the point - are linear pull brakes superior?

If it really requires super hand strength to operate your brakes, I'd
think something else is wrong. Maybe you could give us more details: Is
the bike new? What model? What brake levers? Are the cantilevers the
classic L-shape, or the newer "low profile" shape?

Regarding potential problems: Do the brake shoes need to be replaced?
(Try Kool-Stop Salmon.) Do the cables need to be lubricated or replaced?
Are the cables well aligned, or is there a chance the inner wire is
scraping around some sharp corner? Is there any interference of moving
parts?

Sorry about the delay, lots of home improvements to get through.

The bike is a Ridley XBow. The brakes are Shimano BR-R550's. The levers are Shimano 6800 105 with the internal cables.

I'm using the "F" spreaders that come with the brakes.

I've tried all of these things before but since recovering from my concussion after two and a half years I can't remember these things.

Now I'm sure I could improve the brakes marginally with softer pads I don't know if it would be significant enough to bother with.

Also it appears to me that the "racing" cantilevers are mainly designed to do nothing more than reduce weight. The levers are more perpendicular to the cable but the "Y" in the cable is longer. Does this balance out or actually lighten the brake loads?

I'm not kidding about how much muscle strength it requires to operate. So much that it makes steep downhills dangerous on the bike.

A link to a closeup image of your brakes front and rear would be a big help in diagnosing the problem.

Remember that if you do go to linear pull brakers aka V-brakes you'll need an adapter like a Travel Agent in order to use your 105 brake levers.

I'll second that request for a photo.


--
- Frank Krygowski

On Sunday, December 13, 2015 at 8:46:10 AM UTC-8, Frank Krygowski wrote:
On 12/13/2015 10:54 AM, Sir Ridesalot wrote:
On Sunday, December 13, 2015 at 10:41:23 AM UTC-5, wrote:
On Friday, December 11, 2015 at 3:44:55 PM UTC-8, Frank Krygowski wrote:
On 12/11/2015 5:18 PM, wrote:

To get to the point - are linear pull brakes superior?

If it really requires super hand strength to operate your brakes, I'd
think something else is wrong. Maybe you could give us more details: Is
the bike new? What model? What brake levers? Are the cantilevers the
classic L-shape, or the newer "low profile" shape?

Regarding potential problems: Do the brake shoes need to be replaced?
(Try Kool-Stop Salmon.) Do the cables need to be lubricated or replaced?
Are the cables well aligned, or is there a chance the inner wire is
scraping around some sharp corner? Is there any interference of moving
parts?

Sorry about the delay, lots of home improvements to get through.

The bike is a Ridley XBow. The brakes are Shimano BR-R550's. The levers are Shimano 6800 105 with the internal cables.

I'm using the "F" spreaders that come with the brakes.

I've tried all of these things before but since recovering from my concussion after two and a half years I can't remember these things.

Now I'm sure I could improve the brakes marginally with softer pads I don't know if it would be significant enough to bother with.

Also it appears to me that the "racing" cantilevers are mainly designed to do nothing more than reduce weight. The levers are more perpendicular to the cable but the "Y" in the cable is longer. Does this balance out or actually lighten the brake loads?

I'm not kidding about how much muscle strength it requires to operate. So much that it makes steep downhills dangerous on the bike.

A link to a closeup image of your brakes front and rear would be a big help in diagnosing the problem.

Remember that if you do go to linear pull brakers aka V-brakes you'll need an adapter like a Travel Agent in order to use your 105 brake levers.

I'll second that request for a photo.

How do I post a picture? In the pictures you can see that the angle is a little long un-actuated. But the closer to full-on the closer to 90 degrees the angles get. So the change in angles isn't the problem since the harder you pull the better the leverage gets.

Since the pads are stock I think that I'll try your advice and try a softer higher traction brake pad.

Clive George wrote:
On 13/12/2015 15:54, Sir Ridesalot wrote:

Remember that if you do go to linear pull brakers aka V-brakes you'll
need an adapter like a Travel Agent in order to use your 105 brake levers.

Though if you are meticulous about maintenance and keeping your wheels
true, you can run Vs off road brake levers and they will be very
powerful. But they will need a lot of care - they'd need to be run very
close to the rims.



You can also buy short arm V brakes which are more compatible with road
levers, assuming the reduced clearance at the tire is something you can get
away with.

On Sunday, December 13, 2015 at 9:29:19 AM UTC-8, Ralph Barone wrote:

You can also buy short arm V brakes which are more compatible with road
levers, assuming the reduced clearance at the tire is something you can get
away with.

Ralph, it's on a cross bike with 32 mm mud knobbies on it and while there's quite a bit of clearance at the moment I may have to go to wider tires. The 32's seemed surprisingly good in the mud but they fill up and I'm not sure how the traction is that way since I was careful to do a paved downhill to blow out all of the mud before the next muddy descent.