Poor braking

In article <[email hidden]>

Anthony Jones said:

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).

Agreed - with V-brakes you can't get the cable angle wrong, with cantis
there's a lot of room for variation (and it was sometimes impossible to
get the angle right because of that bizarre straddle-cable arrangement
that Shimano used to use).

dkahn400 said:

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.

I completely agree with all of that. However, there are situations where
extra mechanical advantage is useful (and not just because it can help
to provide better modulation or feel). I can't be the only person who
has reached the bottom of a steep, technical off road descent with
aching fingers...

Anthony

In message <[email hidden]>

Phil Armstrong said:

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 🙂

Depends how many bricks [bottle of beer] you have in yer panniers.

Quoted message said:

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

Phil

--
Gwyn

Phil Armstrong said:

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.

Nice try, but you're wrong. The only rim brake system that compare's to
disks is a nice set of HS33s on ceramic rims. I've got great set of
dual pivot calipers on my road bike and a great set of hydraulic disks
with a 203mm disk at the front on my mtb. If I had the right equipment
I could measure a real difference in the amount of pressure required at
the brake lever to stop either bike. Both set ups work well, the disks
just work a bit better. Maybe because I'm pushing 230lbs I see a
difference.

Just think of those skinny [censored] kids who can bring 50lb full susser to
a complete stop on insane downhill sections, not easy with v brakes and
almost impossible with canti's.

All this is OT to the OP's question, who just needs to clean their rims
and pads. And because I ride both systems I don't see a need for disks
on my road bike, still overkill I think.

Laters,

Marz

in message <[email hidden]>, Phil Armstrong

(') said:

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?

And, indeed, once one has learned it on a mountain bike, it is /just/ as
easy on a road bike.

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

;; better than your average performing pineapple

Simon Brooke said:

in message <[email hidden]>, Phil Armstrong

(') said:

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?

And, indeed, once one has learned it on a mountain bike, it is /just/ as
easy on a road bike.

Or, use a Proper Bike with less tendency to throw you over the bars and
your braking is naturally better while you sit in your comfy chair...

I use Maggie HS33 hydraulic rim brakes on my 'bent. I reckon they're
better than the Avid mech discs I've tried on various demo bikes at
Darth Ben's, and just as good as the hydraulic discs on Roos' Fiero.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

Simon Brooke said:

in message <[email hidden]>, Phil Armstrong

(') said:

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?

And, indeed, once one has learned it on a mountain bike, it is /just/ as
easy on a road bike.

Is that a road bike with drops or a flat bar? I can't seem to get my
bum behind my saddle while reaching for the brakes. Maybe I need to get
back into yoga again.

Laters,

Marz

Peter Clinch said:

Simon Brooke said:

in message <[email hidden]>, Phil Armstrong

(') said:

Marz <[email hidden]> wrote:
> 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?

And, indeed, once one has learned it on a mountain bike, it is /just/ as
easy on a road bike.

Or, use a Proper Bike with less tendency to throw you over the bars and
your braking is naturally better while you sit in your comfy chair...

Hey! All my riding skills become golden once I sit back in a chair with
a cup of tea. And you should hear what I can do on my bike after a
couple of beers, 100ft doubles, 50ft drops and I could beat Lance up my
local hill. 🙂

Quoted message said:

I use Maggie HS33 hydraulic rim brakes on my 'bent. I reckon they're
better than the Avid mech discs I've tried on various demo bikes at
Darth Ben's, and just as good as the hydraulic discs on Roos' Fiero.

When I first tried disks I went from HS33s to Hope Minis (older style
Minis) and they sucked. I could never get the same braking performance
as the HS33s, but I did get the mud clearance I was looking for. It's
only now running el caminos with 203mm disks that I'm seeing a marked
difference in braking performance.

If someone hadn't stolen my hardtail last year I'd still be running a
set of HS33s for XC use, with no plans to change to disks. I guess I
found fault with the statement that 'all' disk brakes do not provide
more power than 'all' rim brakes. (the 'all' is how I read the
statement and maybe not what was meant). My disks brakes out perform my
rim brakes, both of which are working very well and nobody races
downhill mtb with rim brakes.

Laters,

Marz

Laters,

Marz

Marz said:

Nice try, but you're wrong. The only rim brake system that compare's to
disks is a nice set of HS33s on ceramic rims. I've got great set of
dual pivot calipers on my road bike and a great set of hydraulic disks
with a 203mm disk at the front on my mtb. If I had the right equipment
I could measure a real difference in the amount of pressure required at
the brake lever to stop either bike. Both set ups work well, the disks
just work a bit better. Maybe because I'm pushing 230lbs I see a
difference.

The amount of pressure required is immaterial. As long as you can
generate enough braking to lift the back wheel that is the limit. By
straightening the arms and moving the weight of the body right back as
you described you can increase the limit, but you can still reach it
with properly set up rim brakes. Your idea of somehow pushing the
weight down appears to be purely psychological. It is not possible to
make yourself heavier by an effort of will.

--
Dave...

Marz said:

Hey! All my riding skills become golden once I sit back in a chair with
a cup of tea. And you should hear what I can do on my bike after a
couple of beers, 100ft doubles, 50ft drops and I could beat Lance up my
local hill. 🙂

I've only tried water and juice on the move while I'm in my comfy chair,
and they have yet to delude me I can get a heavy recumbent tourer up a
hill faster than Mr. Armstrong on a racer... ;-)

But I can easily apply enough pressure to lock /both/ wheels on it, and
I could still do that with the V brakes that preceded the Maggies as
long as they'd not been too long since fettling. The Maggies never need
fettling though, and I can always get away with fingertips.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

Peter Clinch said:

Marz said:

Hey! All my riding skills become golden once I sit back in a chair with
a cup of tea. And you should hear what I can do on my bike after a
couple of beers, 100ft doubles, 50ft drops and I could beat Lance up my
local hill. 🙂

I've only tried water and juice on the move while I'm in my comfy chair,
and they have yet to delude me I can get a heavy recumbent tourer up a
hill faster than Mr. Armstrong on a racer... ;-)

But I can easily apply enough pressure to lock /both/ wheels on it, and
I could still do that with the V brakes that preceded the Maggies as
long as they'd not been too long since fettling. The Maggies never need
fettling though, and I can always get away with fingertips.

Ahhh, proper bike, sorry I'm suffering from long term brain freeze and
missed your point. I used to ride a Crystal Engineering 'bent and trike
(pre-ICE days) and I was always able to lock both wheels with ease, but
I think the relaxed hand postion on the under seat bar made it easier
to apply alot of pressure to the brake levers. Due to the really low
centre of gravity I could lock up the trike and come to crashing halt
without fear of going over the bars. I've been looking at what ICE have
done with the Trike recently and it looks really good, but I've always
got my eye on a Mike Burrows machine. All I've got to do now is
convince the wife I need another bike, maybe I should solve world peace
first.

Laters,

Marz

dkahn400 said:

Marz said:

Nice try, but you're wrong. The only rim brake system that compare's to
disks is a nice set of HS33s on ceramic rims. I've got great set of
dual pivot calipers on my road bike and a great set of hydraulic disks
with a 203mm disk at the front on my mtb. If I had the right equipment
I could measure a real difference in the amount of pressure required at
the brake lever to stop either bike. Both set ups work well, the disks
just work a bit better. Maybe because I'm pushing 230lbs I see a
difference.

The amount of pressure required is immaterial. As long as you can
generate enough braking to lift the back wheel that is the limit. By
straightening the arms and moving the weight of the body right back as
you described you can increase the limit, but you can still reach it
with properly set up rim brakes. Your idea of somehow pushing the
weight down appears to be purely psychological. It is not possible to
make yourself heavier by an effort of will.

--
Dave...

Required pressure is not immaterial as I can reach this braking limit
sooner and with less effort with disks than with rim brakes. Are you
saying that any additional power I may get from disk brakes is mute
because I've already reached the braking limitation of lifting the back
wheel?

It's not my idea, it's fact. While one can unweight a bike to lift it
over roots or potholes, one can also weight the bike for cornering and
braking. It's akin to 'twisting' the bar grips back to gain real wheel
grip on steep climbs. You can try it yourself, pull a short skid on
dirt or tarmac using just enough power to lock the rear wheel (or both
if on dirt). Now try it again, but this time attempt to 'jump' on the
pedals during the skid, you'll increase traction to the wheel and
unlock it and maybe stop sooner.

Laters,

Marz

Marz said:

Required pressure is not immaterial as I can reach this braking limit
sooner and with less effort with disks than with rim brakes. Are you
saying that any additional power I may get from disk brakes is mute
because I've already reached the braking limitation of lifting the back
wheel?

I presume you mean "moot"? In terms of stopping power, yes. Any
additional braking will pitch you over the bars.

Quoted message said:

It's not my idea, it's fact. While one can unweight a bike to lift it
over roots or potholes, one can also weight the bike for cornering and
braking. It's akin to 'twisting' the bar grips back to gain real wheel
grip on steep climbs. You can try it yourself, pull a short skid on
dirt or tarmac using just enough power to lock the rear wheel (or both
if on dirt). Now try it again, but this time attempt to 'jump' on the
pedals during the skid, you'll increase traction to the wheel and
unlock it and maybe stop sooner.

I think I misunderstood what you were saying. By raising your centre of
gravity you will create extra downforce, at least for the short time
your centre of gravity is actually rising. This will allow you to apply
the rear brake harder before the wheel skids, but again this is not
really relevant to maximum braking. With conventional geometry maximum
braking is determined solely by the point at which the rear wheel
starts to lift. At this point the rear brake has no effect, therefore
the rear brake and the ability to perform rear wheel skids are
irrelevant. As long as the front brake is powerful enough to lift the
rear wheel in your fully braced posture, that alone determines maximum
braking. Futhermore it would appear that if you are actively raising
your centre of gravity you may well be making it easier to pitch over
the bars, and therefore be decreasing your maximum braking rather than
increasing it.

--
Dave...

Marz said:

Phil Armstrong said:

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.

Nice try, but you're wrong. The only rim brake system that compare's to
disks is a nice set of HS33s on ceramic rims. I've got great set of
dual pivot calipers on my road bike and a great set of hydraulic disks
with a 203mm disk at the front on my mtb. If I had the right equipment
I could measure a real difference in the amount of pressure required at
the brake lever to stop either bike. Both set ups work well, the disks
just work a bit better. Maybe because I'm pushing 230lbs I see a
difference.

But we weren't discussing mechanical advantage. At least I wasn't!

Like I said: discs have advantages over rim brakes. Stronger braking
for less finger pressure is one of them. What they don't have is
better maximum braking force because the limiting factor is the
geometry of the bicycle, not the maximum achievable braking force.

Quoted message said:

Just think of those skinny [censored] kids who can bring 50lb full susser to
a complete stop on insane downhill sections, not easy with v brakes and
almost impossible with canti's.

That's about control & brake feel, not brake strength. Indeed, going
downhill, you have to apply even less braking force at the wheel to
tip the rider over the bars than on the flat. As you say, discs are a
better than rim brakes at this, mainly due to the mechanical advantage
again I'd guess.

Quoted message said:

All this is OT to the OP's question, who just needs to clean their rims
and pads. And because I ride both systems I don't see a need for disks
on my road bike, still overkill I think.

Exactly. Horses for courses. For max-braking force discs aren't any
better than rim brakes (given that both are properly set up), but they
can be the right choice for other reasons: To "cross the threads", one
salutary advantage of discs is that they don't wear your rims out, so
you don't have to worry about your wheels going pop on a steep bit 🙂

Phil

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

Marz said:

It's not my idea, it's fact. While one can unweight a bike to lift it
over roots or potholes, one can also weight the bike for cornering and
braking. It's akin to 'twisting' the bar grips back to gain real wheel
grip on steep climbs. You can try it yourself, pull a short skid on
dirt or tarmac using just enough power to lock the rear wheel (or both
if on dirt). Now try it again, but this time attempt to 'jump' on the
pedals during the skid, you'll increase traction to the wheel and
unlock it and maybe stop sooner.

As has been pointed out elsewhere in this thread, the limit of braking
is when the torque on the rider + bike due to the rider pushing
against the bars against the braking of the bike is just short that
required to lift the back wheel. Any more braking force will tip the
rider over the bars.

It's been asserted elsewhere in this thread that rim brakes are
perfectly capable of reaching this limiting braking force. A rider
cannot apply more braking force to the wheels than this limit[1],
regardless of braking technology used, since to do so will result in
the rider going over the bars.

If someone brakes hard enough to be just under this limit then bounces
up and down on the bike, I think you'll find that they'll be meeting
the ground in front of their bicycle very quickly 🙂

Phil

[1] On a standard bicycle. Low-rider recumbents where the rider's
centre of mass is at the same level as the wheel axles need not
apply 🙂

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

dkahn400 said:

Marz said:

Required pressure is not immaterial as I can reach this braking limit
sooner and with less effort with disks than with rim brakes. Are you
saying that any additional power I may get from disk brakes is mute
because I've already reached the braking limitation of lifting the back
wheel?

I presume you mean "moot"? In terms of stopping power, yes. Any
additional braking will pitch you over the bars.

Moot, I ment moot.

Quoted message said:

Quoted message said:

It's not my idea, it's fact. While one can unweight a bike to lift it
over roots or potholes, one can also weight the bike for cornering and
braking. It's akin to 'twisting' the bar grips back to gain real wheel
grip on steep climbs. You can try it yourself, pull a short skid on
dirt or tarmac using just enough power to lock the rear wheel (or both
if on dirt). Now try it again, but this time attempt to 'jump' on the
pedals during the skid, you'll increase traction to the wheel and
unlock it and maybe stop sooner.

I think I misunderstood what you were saying. By raising your centre of
gravity you will create extra downforce, at least for the short time
your centre of gravity is actually rising. This will allow you to apply
the rear brake harder before the wheel skids, but again this is not
really relevant to maximum braking. With conventional geometry maximum
braking is determined solely by the point at which the rear wheel
starts to lift. At this point the rear brake has no effect, therefore
the rear brake and the ability to perform rear wheel skids are
irrelevant. As long as the front brake is powerful enough to lift the
rear wheel in your fully braced posture, that alone determines maximum
braking. Futhermore it would appear that if you are actively raising
your centre of gravity you may well be making it easier to pitch over
the bars, and therefore be decreasing your maximum braking rather than
increasing it.

--
Dave...

Ok, I've done a poor job of explaining what I'm talking about. To
complete a bunny hop you need to push yourself down into the bike,
compressing the suspension and or tyres before exploding verticaly to
get lift. Imagine compressing the tyres into the ground while you brake
and not exploding upwards. I use this technique for late braking into
corners, I 'jump' down onto the bars and pedals, pushing both wheels
into the ground, dropping my body low into the direction of the corner
while braking like crazy. Breaking down the movement into steps, I
guess I drop down rapidly into the saddle and it's the slower push up
and back that adds the additional weight to the wheels.

I think I've done another [censored] job of explaining.

I'm going to have to study this while I ride tomorrow.

Laters,

Marz

in message <[email hidden]>, Phil Armstrong

(') said:

Marz said:

Just think of those skinny [censored] kids who can bring 50lb full susser to
a complete stop on insane downhill sections, not easy with v brakes
and almost impossible with canti's.

That's about control & brake feel, not brake strength. Indeed, going
downhill, you have to apply even less braking force at the wheel to
tip the rider over the bars than on the flat. As you say, discs are a
better than rim brakes at this, mainly due to the mechanical advantage
again I'd guess.

Sensitivity. Hydraulic brakes don't suffer from cable stiction, and so
it's much easier to modulate a precise amount of braking force. I've
been saying for some time that there's far more difference between cable
operated and hydraulic brakes than between rim and disk brakes.

Would you prefer to do a technical downhill section with Magura HS33s, or
Tektro cable operated disks?

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

;; L'etat c'est moi -- Louis XVI
;; I... we... the Government -- Tony Blair

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.

Disks must have some advantages over rim brakes. The one I can see
would be that

- your pads are pressing flat against a disk and compressing it rather
than pressing on the sides of a u-section rim.

- you have separate mechanical system for supporting the rider (the
wheel rim) and the braking system, which will have different and
probably competing design goals.

- you can run disks hotter, no need to keep them cool because you've
got a a tyre in contact with the braking surface.

Disks just seem like a better solution to me and the desire to stick
with traditional methods of braking is just that, tradition.

Chris
--
Chris Eilbeck

Phil Armstrong wrote on 23/06/2006 19:15 +0100:

Quoted message said:

It's been asserted elsewhere in this thread that rim brakes are
perfectly capable of reaching this limiting braking force.

Not on tandems ;-)

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

Phil Armstrong said:

Marz said:

It's not my idea, it's fact. While one can unweight a bike to lift it
over roots or potholes, one can also weight the bike for cornering and
braking. It's akin to 'twisting' the bar grips back to gain real wheel
grip on steep climbs. You can try it yourself, pull a short skid on
dirt or tarmac using just enough power to lock the rear wheel (or both
if on dirt). Now try it again, but this time attempt to 'jump' on the
pedals during the skid, you'll increase traction to the wheel and
unlock it and maybe stop sooner.

As has been pointed out elsewhere in this thread, the limit of braking
is when the torque on the rider + bike due to the rider pushing
against the bars against the braking of the bike is just short that
required to lift the back wheel. Any more braking force will tip the
rider over the bars.

You shouldn't be pushing against the bars, the bars are for steering,
braking and shifting gear, most (98.7657%(yes I made it up)) of your
weight should be on your pedals.

Quoted message said:

It's been asserted elsewhere in this thread that rim brakes are
perfectly capable of reaching this limiting braking force. A rider
cannot apply more braking force to the wheels than this limit[1],
regardless of braking technology used, since to do so will result in
the rider going over the bars.

But a better braking technique increases the limit to a point (I've
found) beyond the capabilities of cable operated rim brakes. This is
based mostly through mtb experience rather than road riding.

Quoted message said:

If someone brakes hard enough to be just under this limit then bounces
up and down on the bike, I think you'll find that they'll be meeting
the ground in front of their bicycle very quickly 🙂

Bounce, once and down, if one can bounce down. All this [censored] from
me is going land me with face plant this weekend as I try prove my
point.

laters,

Marz

Quoted message said:

Phil

[1] On a standard bicycle. Low-rider recumbents where the rider's
centre of mass is at the same level as the wheel axles need not
apply 🙂

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