Poor braking

Brendan Halpin said:

Yesterday it rained on my commute -- strange to say it but it
hadn't rained here for weeks -- and it struck me forcibly how [censored]
my brakes are in the wet. Koolstop salmon pads, cantilever brakes,
all in good order, but the wet-weather stopping power is far less
than I would like.

What options have I to improve the performance?

Brendan
--
Brendan Halpin, Department of Sociology, University of Limerick, Ireland
Tel: w +353-61-213147 f +353-61-202569 h +353-61-338562; Room F2-025 x 3147
[email hidden] http://www.ul.ie/sociology/brendan.halpin.html

Simple stuff first, I suppose:
Unhook the straddle cable, check that the main cable is moving smoothly
from the lever to the yoke for the straddle cable with no binding.
Check that each cantilever arm is free to move smoothly (against the
preassure of the return spring) until the block reaches the rim, with
no binding or stiff spots in the movement. Check that the block meets
the rim squarely.

Check brake pad surfaces are clean, with nothing embeded in them and
not glazed or contaminated.
Check that the entire surface of the block is wearing evenly - if not
your brake blocks may not be square on to your rims - obviously, this
will reduce brakeing power significantly
A gentle rub with a file to expose fresh rubber wouldn't hurt, but no
more than a that.

Check that brakeing surfaces of the rims the rims are clean and
uncontaminated - rub around the surface with a clean cloth and a little
solvent to remove any dirt or oily/greasy stuff that may have built up
there - clean until no more dirt comes away on the cloth.

You need to clean both the pads and the rim surface at the same time -
if there is a problem with contamination, and you only clean one, it'll
recontaminate the other one the next time the brakeis applied.

Finally, AUSHTA:
http://sheldonbrown.com/canti-trad.html
....how to adjust cantilever brakes for best performance.
He also has a good article on the various kinds of
brakes-what-mount-on-frame-bosses here:
http://sheldonbrown.com/cantilever-adjustment.html

hth,

bookieb.

In article <[email hidden]>, Paul

Boyd () said:

Brendan Halpin said the following on 22/06/2006 08:53:

Quoted message said:

As far as I can tell, no one sells disc brakes with levers for drop
bars.

You can get cable operated discs that work with V-brake levers, and you
can get V-brake levers that work on dropped bars. I know, because I
have them (V-brake levers on dropped bars, that is)

As to whether or not that will actually improve the braking performance
in the wet is another issue, as is whether you can get appropriate forks
for mounting the disc brakes on a road bike. I guess you can.

Some of the Avid mechanical (spits) discs are designed to work with
regular (i.e. non-linear pull stylee) levers.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
Mushroom! Mushroom!

In article <[email hidden]>, Paul

Boyd () said:

Brendan Halpin said the following on 22/06/2006 08:53:

Quoted message said:

As far as I can tell, no one sells disc brakes with levers for drop
bars.

You can get cable operated discs that work with V-brake levers, and you
can get V-brake levers that work on dropped bars. I know, because I
have them (V-brake levers on dropped bars, that is)

As to whether or not that will actually improve the braking performance
in the wet is another issue, as is whether you can get appropriate forks
for mounting the disc brakes on a road bike. I guess you can.

Some of the Avid mechanical (spits) discs are designed to work with
regular (i.e. non-linear pull stylee) levers.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
Mushroom! Mushroom!

POHB said:

IME V-brakes grip better than cantilever brakes

I've found there to be little difference, and can't really see any
mechanical reason for V-brakes to be significantly better.

My suspicion is that most people who have found cantis to be lacking in
comparison with V-brakes were suffering from poor setup (which is not
surprising, considering how fiddly some models were to get right).

Anthony

POHB said:

IME V-brakes grip better than cantilever brakes

I've found there to be little difference, and can't really see any
mechanical reason for V-brakes to be significantly better.

My suspicion is that most people who have found cantis to be lacking in
comparison with V-brakes were suffering from poor setup (which is not
surprising, considering how fiddly some models were to get right).

Anthony

Brendan Halpin said:

Yesterday it rained on my commute -- strange to say it but it
hadn't rained here for weeks -- and it struck me forcibly how [censored]
my brakes are in the wet. Koolstop salmon pads, cantilever brakes,
all in good order, but the wet-weather stopping power is far less
than I would like.

What options have I to improve the performance?

Was it raining heavily? If so, and the brakes work OK in the dry and
light rain, I don't think it's worth making any changes, considering only
the small minority of your mileage will be in heavy rain. Just allow some
extra stopping distance for the pads to wipe the water off the rim.

However, if braking is also not very good in the dry, you could have a go
with different cable adjustments -- see www.sheldonbrown.com -- or try a
front dual pivot caliper brake.

~PB

bookieb said:

Simple stuff first, I suppose:
Unhook the straddle cable, check that the main cable is moving smoothly
from the lever to the yoke for the straddle cable with no binding.
Check that each cantilever arm is free to move smoothly (against the
preassure of the return spring) until the block reaches the rim, with
no binding or stiff spots in the movement. Check that the block meets
the rim squarely.

All that is in order, and dry performance is fine, but I will
investigate the state of the surfaces.

Quoted message said:

Finally, AUSHTA:
http://sheldonbrown.com/canti-trad.html
...how to adjust cantilever brakes for best performance.
He also has a good article on the various kinds of
brakes-what-mount-on-frame-bosses here:
http://sheldonbrown.com/cantilever-adjustment.html

Thanks for the pointer -- I had seen the argument about changing
the link wire length but didn't know where to find it again.

With the "traditional center-pull cantilever brakes", quill stem,
conventional-geometry 531 frame, this 7-yo bike is starting to feel
like an antique!

Brendan
--
Brendan Halpin, Department of Sociology, University of Limerick, Ireland
Tel: w +353-61-213147 f +353-61-202569 h +353-61-338562; Room F2-025 x 3147
[email hidden] http://www.ul.ie/sociology/brendan.halpin.html

Brendan Halpin said:

druidh said:

Brendan Halpin said:

but the wet-weather stopping power is far less
than I would like.

What options have I to improve the performance?

Quoted message said:

They're called disks. Have a look around, you'll see loads.

As far as I can tell, no one sells disc brakes with levers for drop
bars.

Brendan

I've got Avid BB7 mechanical disks on my road bike with Shimano 105 levers.

http://www.konaworld.com/shopping_cart/FrontEnd/Products/product_detail.aspx?productid=358&parentid=253

druidh

in message <[email hidden]>, Brendan Halpin

(') said:

Yesterday it rained on my commute -- strange to say it but it
hadn't rained here for weeks -- and it struck me forcibly how [censored]
my brakes are in the wet. Koolstop salmon pads, cantilever brakes,
all in good order, but the wet-weather stopping power is far less
than I would like.

What options have I to improve the performance?

Clean your rims with alcohol or other solvent. Very small amounts of
greasy or waxy contamination will affect braking performance. Remember
to also clean the pads.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; When all else fails, read the distractions.

in message <[email hidden]>, Brendan Halpin

(') said:

druidh said:

Brendan Halpin said:

but the wet-weather stopping power is far less
than I would like.

What options have I to improve the performance?

Quoted message said:

They're called disks. Have a look around, you'll see loads.

As far as I can tell, no one sells disc brakes with levers for drop
bars.

They do. But the idea that disk brakes have more stopping power than well
adjusted rim brakes is just false.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

... a mild, inoffensive sadist...

Simon Brooke said:

in message <[email hidden]>, Brendan Halpin

(') said:

druidh said:

Brendan Halpin wrote:
> but the wet-weather stopping power is far less
> than I would like.
>
> What options have I to improve the performance?

Quoted message said:

They're called disks. Have a look around, you'll see loads.

As far as I can tell, no one sells disc brakes with levers for drop
bars.

They do. But the idea that disk brakes have more stopping power than
well adjusted rim brakes is just false.

Except for the fact that it isn't, you're correct.

A small disk of stainless steel is a lot more robust than a bit of alloy
that's doing dual duty with conflicting needs, so the forces applied can be
a lot greater, and the braking surface can be much closer and the pads can
be much harder and more abrasive, so in the end, all this more than
compensates for the smaller rolling diameter and lowered ability to
dissipate heat.

A

Ambrose Nankivell said:

Except for the fact that it isn't, you're correct.

A small disk of stainless steel is a lot more robust than a bit of
alloy that's doing dual duty with conflicting needs, so the forces
applied can be a lot greater, and the braking surface can be much
closer and the pads can be much harder and more abrasive, so in the
end, all this more than compensates for the smaller rolling diameter
and lowered ability to dissipate heat.

Along the same lines: the caliper doesn't need 3 inches of tyre and mud
clearance, so can be much stiffer, again allowing much greater
mechanical advantage.

Anthony

in message <[email hidden]>, Ambrose Nankivell

(') said:

Simon Brooke said:

in message <[email hidden]>, Brendan Halpin

(') said:

druidh <[email hidden]> writes:

> Brendan Halpin wrote:
>> but the wet-weather stopping power is far less
>> than I would like.
>>
>> What options have I to improve the performance?

> They're called disks. Have a look around, you'll see loads.

As far as I can tell, no one sells disc brakes with levers for drop
bars.

They do. But the idea that disk brakes have more stopping power than
well adjusted rim brakes is just false.

Except for the fact that it isn't, you're correct.

The limit on stopping power on a bicycle brake is unweighting the back
wheel. You can unweight the back wheel satisfactorily with any of V
brake, cantilever, dual pivot caliper. Any more stopping power than that
is impossible, therefore disks don't have it.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

my other car is #<Subr-Car: #5d480>
;; This joke is not funny in emacs.

Anthony Jones said:

Ambrose Nankivell said:

Except for the fact that it isn't, you're correct.

A small disk of stainless steel is a lot more robust than a bit of
alloy that's doing dual duty with conflicting needs, so the forces
applied can be a lot greater, and the braking surface can be much
closer and the pads can be much harder and more abrasive, so in the
end, all this more than compensates for the smaller rolling diameter
and lowered ability to dissipate heat.

Along the same lines: the caliper doesn't need 3 inches of tyre and mud
clearance, so can be much stiffer, again allowing much greater
mechanical advantage.

The braking power of a conventional upright bicycle on dry tarmac is
limited by its geometry, not by the force that can be applied to the
braking surface. The point where the rear wheel starts to lift is the
limit of braking. If this degree of braking can be achieved with a rim
brake then it simply cannot be improved upon with any kind of hub or
disk brake.

Where a disk brake might be superior is in modulation or feel, and
performance in the wet, which was the original point of this thread.
The trade off for these advantages is the increased weight of the
braking system and the fork, which is why you rarely see disk brakes on
road bikes.

--
Dave...

Simon Brooke said:

The limit on stopping power on a bicycle brake is unweighting the back
wheel. You can unweight the back wheel satisfactorily with any of V
brake, cantilever, dual pivot caliper. Any more stopping power than that
is impossible, therefore disks don't have it.

Not in all circumstances. I'm nowhere near lifting the back wheel
with full-effort braking in the wet, to bring things back to the
starting point.

Brendan
--
Brendan Halpin, Department of Sociology, University of Limerick, Ireland
Tel: w +353-61-213147 f +353-61-202569 h +353-61-338562; Room F2-025 x 3147
[email hidden] http://www.ul.ie/sociology/brendan.halpin.html

Simon Brooke said:

in message <[email hidden]>, Ambrose Nankivell

(') said:

Simon Brooke said:

in message <[email hidden]>, Brendan Halpin
([email hidden]'😉 wrote:

> druidh <[email hidden]> writes:
>
>> Brendan Halpin wrote:
>>> but the wet-weather stopping power is far less
>>> than I would like.
>>>
>>> What options have I to improve the performance?
>> They're called disks. Have a look around, you'll see loads.
> As far as I can tell, no one sells disc brakes with levers for drop
> bars.
They do. But the idea that disk brakes have more stopping power than
well adjusted rim brakes is just false.

Except for the fact that it isn't, you're correct.

The limit on stopping power on a bicycle brake is unweighting the back
wheel. You can unweight the back wheel satisfactorily with any of V
brake, cantilever, dual pivot caliper. Any more stopping power than that
is impossible, therefore disks don't have it.

Except that the OP was complaining about poor performance in the wet -
where disks DO have it.

druidh

dkahn400 said:

Anthony Jones said:

Ambrose Nankivell said:

Except for the fact that it isn't, you're correct.

A small disk of stainless steel is a lot more robust than a bit of
alloy that's doing dual duty with conflicting needs, so the forces
applied can be a lot greater, and the braking surface can be much
closer and the pads can be much harder and more abrasive, so in the
end, all this more than compensates for the smaller rolling diameter
and lowered ability to dissipate heat.

Along the same lines: the caliper doesn't need 3 inches of tyre and mud
clearance, so can be much stiffer, again allowing much greater
mechanical advantage.

The braking power of a conventional upright bicycle on dry tarmac is
limited by its geometry, not by the force that can be applied to the
braking surface. The point where the rear wheel starts to lift is the
limit of braking. If this degree of braking can be achieved with a rim
brake then it simply cannot be improved upon with any kind of hub or
disk brake.

Where a disk brake might be superior is in modulation or feel, and
performance in the wet, which was the original point of this thread.
The trade off for these advantages is the increased weight of the
braking system and the fork, which is why you rarely see disk brakes on
road bikes.

Only if you remain seated on the saddle like a lemon. To take full
advantage of disk brakes you need to get your [censored] behind the saddle,
shifting you weight over the back wheel. To increase traction with the
ground and further increase braking performance you'll need to 'push'
the bike into the ground, sort of like a reverse bunny hop. All of
which is easy on a mtb and not so easy on a road bike.

Hydraulic disk brakes do allow to stop quicker than cable operated rim
brakes, but you have to change your riding style to realise the
advantage.

Laters,

Marz

in message <[email hidden]>, Brendan Halpin

(') said:

Simon Brooke said:

The limit on stopping power on a bicycle brake is unweighting the back
wheel. You can unweight the back wheel satisfactorily with any of V
brake, cantilever, dual pivot caliper. Any more stopping power than
that is impossible, therefore disks don't have it.

Not in all circumstances. I'm nowhere near lifting the back wheel
with full-effort braking in the wet, to bring things back to the
starting point.

Degrease your rims.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
Ye hypocrites! are these your pranks? To murder men and give God thanks?
Desist, for shame! Proceed no further: God won't accept your thanks for
murther
-- Robert Burns, 'Thanksgiving For a National Victory'

Marz said:

Only if you remain seated on the saddle like a lemon. To take full
advantage of disk brakes you need to get your [censored] behind the saddle,
shifting you weight over the back wheel. To increase traction with the
ground and further increase braking performance you'll need to 'push'
the bike into the ground, sort of like a reverse bunny hop. All of
which is easy on a mtb and not so easy on a road bike.

And what's to stop you adopting exactly the same position with rim
brakes?

Quoted message said:

Hydraulic disk brakes do allow to stop quicker than cable operated rim
brakes, but you have to change your riding style to realise the
advantage.

Both designs of brakes should be capable of applying enough braking
force to tip you over the front wheel. If your rim brakes can't do
that, they aren't set up right 🙂

Hydraulic disks may have other advantages (and disadvantages) but
raw stopping power isn't one of them.

Phil

--
http://www.kantaka.co.uk/ .oOo. public key: http://www.kantaka.co.uk/gpg.txt

Brendan Halpin said:

Simon Brooke said:

The limit on stopping power on a bicycle brake is unweighting the back
wheel. You can unweight the back wheel satisfactorily with any of V
brake, cantilever, dual pivot caliper. Any more stopping power than that
is impossible, therefore disks don't have it.

Not in all circumstances. I'm nowhere near lifting the back wheel
with full-effort braking in the wet, to bring things back to the
starting point.

Clean the rims and the surface of the brake pads. Report back if it
doesn't make any difference.

cheers, Phil

--
http://www.kantaka.co.uk/ .oOo. public key: http://www.kantaka.co.uk/gpg.txt