You might like this then.
---
EDIT Thanks to DeeEight
http://www.retrobike.co.uk/forum/viewto ... 29#1436929
http://206.75.155.18/kmr/tech.html
/EDIT
Brakes FAQ
OOPS... went and did it again... wrote a FAQ thingy about cantilever
brake setup... mostly to do with the V-brake myth...
Jeff Bogdanovich I have new: STX cantis, PC-7s, and Mavic 221 rims and my brakes are not
>very powerful at all. Is there anything you would recomend that would be
>cheap and effective? Thanks.
The first trick to good brake performance is to chuck the stoopid shimano
straddle-cable guides (the dinky ones with rubber tubes for the left side
of the brake). The next thing to do is get a diacompe (or aftermarket)
cable-hanger and straddle cable (Tektro makes a nice Avid clone thats damn
good). The solution to good braking comes down to understanding (uh oh, I
sense a tech tip for my page in the process of being written here) how
cantilever brakes works. (see below for the long explanation).
>PS: I have recently come accross a set of '95 XTR shifter/brake levers
>and cantis, do you think these would be any better?
Well, sorta, you can set the pads a little further from the rim and get the same
stopping power as now or set them the same and get MORE stopping power.
Ok, in brief (which for me is MANY paragraphs), cantilever brakes (which
include the much talked about, but quite OVER-rated v-brakes) as well
as U-brakes and Power-Cam brakes, and road brakes all work on the principle
of leverage. You apply X force at one end of a lever, and get Y force at the other
end. Now obviously to get more force at the pads, you need to increase the force
on the end of the cantilever arm. But more force usually requires more effort from
your fingers, which isn't what people want. Riders want to be able to stop using
less force from their fingers.
How do you do this? Simple, increase the mechanical advantage (leverage) in the
brake system somehow. Most Cantilever (low-profile and older wide-profile) use
about a 1.5:1 leverage ratio, and most levers use around a 4:1 leverage ratio.
So If a Rider pulls the lever with say, 5 Ibs of force, then the cable pulls the
brake arm with 20 Ibs of force, and the pad moves with about 30 Ibs of force.
Presto... reduced braking effort. Now in order to get this force from the hand
to the brakepad, you need some way to actuate the brake remotely from the
handlebar (this is also where the mystery in brake setup comes in). This
is usually done with a steel cable though some systems do use hydraulics
or steel rods, or a combination of the three. For this FAQ, I'll be focusing
on cable-actuated brakes.
Most cantilevers use a straddle-cable and cable-yoke system to actuate BOTH
brakearms simultaneously, and it is this straddle-cable which plays one of
the big roles in determining brake performance. The Angle at which the cable
meets the brakearm, relative to the arm's position, affects how much leverage
the arm produces. A steep angle reduces the leverage, but moves the brake arm
further for a given movement of the lever, while a shallow angle increases the
leverage but reduces the distance the brake arm moves for a given movement of
the brake lever. The default setting for the straddle cable used by most
people is with a 90 degree angle from the arm to the yoke ( I must really get
around to providing some pictures for these tips). This produces a neutral
influence on the overall leverage, ensuring that 1mm of cable pull at the
lever means both sides of the straddle cable pull the arms inwards 1mm as
well. Unfortunetly this is rather simplistic, as the moment you pull on the
brake lever, all the cable angles start to change.
Now to get MORE leverage into the system, there are 3 ways you can do it...
#1 is to increase the leverage ratio of the brake lever, which is done with
shimano servowave levers, some models of diacompe levers (SS-5 for example),
and many aftermarket levers (Avid, Crystal Design, etc). The problem with
this method is that the straddle cable angle still affects the overall
leverage of the system. Also most high-leverage brake levers also move LESS
brake cable overall (the cable-pull dilema) which can limit the setup choices
available for a given lever feel. Alot of people are STILL hung-up on the
notion that a firm lever feel equates to powerful brakes so the always setup
their cantilevers to duplicate this lever feel, which leads to the extra
hand effort being required for a given amount of brake force being applied to
the pads.
#2 is to increase the leverage ratio of the cantilever, which is what V-brakes do,
as well as Westpine TAC, Avid TriAlignII, Paul's Stoplight, Marinotive CheapTrick,
etc. This of course can run into problems with the straddle cable setup, as
people try to maintain a firm lever feel. Long-arm cantilevers can ALSO run
into heel-clearance problems when used on smaller frames UNLESS they are of
the low to zero profile type.
#3 is to alter the straddle cable angle. This is the simplest method, but incurs
a problem in that a lower angle requires a greater cable pull at the lever to
move the arms the same distance as with a higher angle. This leads to the
mushy-lever feel many people experience, where they pull the lever all the way
to the grips and can't even lock the wheel. What people fail to understand
though is that the mushy feel is what they REALLY want. A firm lever requires
a greater effort to actuate than a soft lever. So what do people continue to
insist on doing?!? Setup their brakes for a firm lever feel... I've even found
people setting up their v-brakes & v-brake levers with super-close pads and a
ultrafirm lever feel. I haven't the time or patience to tell them that they've
just defeated the purpose of V-brakes (that of increased leverage and pad
clearance over standard shimano Canti's).
Shimano's solution, before the v-brakes was to design new straddle-cable
carriers which when properly (to shimano spec) set would produce a neutral-
cable angle (90 degrees) and therefore all the braking force would come from
the levers and brakes. Hence the Servowave levers (standard on Deore DX/XT/XTR
since 1991, optional on LX since 1993) produced more leverage, and made the
shimano low-profile brakes better stoppers. With the new V-brake design,
shimano has decided to eliminate the straddle-cable altogether, and switch
from hi-leverage levers to hi-leverage cantilevers. The leverage has increased
somewhat as a result, and because shimano has used a long-cable pull design for
their levers, they minimized one of the flaws of long-arm cantilever brakes,
their need for increased cable pull to maintain a given lever feel and
amount of modulation.
Now for those who do not want to upgrade to V-brakes, the best solutions is to
experiment with their straddle-cable position/angle (raising or lowering the
carrier increases or decreases the leverage - low for more leverage, high for
less leverage). A softer lever feel means more leverage, and less pad movement
for a given amount of lever travel, and vice versa for a firm lever feel.
If you only want to partially upgrade, be aware that v-brake levers tend to have
less leverage than most regular levers, so you'll want to lower the straddle-
cable on regular canti's if you just upgraded the shifters/levers part (because
the '96 STI units are now reasonably priced), or actually jury-rig your v-brake
canti's to work with a straddle-cable (which when set at the neutral 90 degree
angle will result in all the extra leverage of the v-brakes, and enough cable
pull from your regular levers to actuate the v-brakes fully!) as I've done with
a few sets. The latter method can actually produce BETTER performance than
V-brakes and V-brake levers but shimano reps will of course advise against it,
or make some other excuse... usually market driven to get you to buy their
levers...
Oh, for those who want to do the math for the leverage increase/degrease of
various straddle-cable angles... the formula is pretty simple if you took
trig in high-school.
The formula as it now stands (unless some other engineering professor wants
to contradict the engineering professor I got the revised formula from) is...
1/Cos(X) * Sin(Y) * Da/Db
Confused? You should be...
X is the angle of the yoke and straddle cable. Contrary to what some deluded
souls might think, the yoke (straddle cable carrier) is NOT just an accessory
which pulls the straddle cable and moves the brake arms together. It is
actually serving the role as an ENTIRELY seperate, but still intergrated lever
system, that also affects the brake arms. Change the angle of the straddle cable
as it leaves the yoke and you change the overall leverage ratio of the brake.
The simplest way to measure the angle between the two sides of the straddle
cable, and then divide by two. So if the angle between both ends of the
straddle cable is 90 degrees, then the yoke angle (X) is 45 degrees. There
is no PERFECT angle for this part of the equation. Its all a matter of user
choice.
Y is the angle that the straddle cable pulls on the brake arm, relative to the
brake arm pivot. Draw an imaginary line from the cable fixing bolt to the pivot
point. Next measure the angle at which the straddle cable pulls on the brakearm
in relation to this imaginary line. The optimum angle for Y is 90 degrees.
Unfortunetly, since the angle constantly changes as the brake arm moves, its
not really worth worrying about. Just try and setup the brakes so the angle
stays as close to 90 degrees as you can get it when the brakepads are actually
touching the rim.
Da is the distance between the cable fixing bolt and the brake arm pivot, while
Db is distance between the brake arm pivot and the brake pad. In otherwords,
this is the basic leverage ratio for the brakearm. Normal cantilevers usually
have a ratio of around 1.5 to 2.0, while V-style brakes come in around 3.0 to
3.25.
AND before anyone points out that the formula should be...
2(1/Cos(X) * Sin(Y) * Da/Db
I'd like to mention that they are WRONG. Why? Simple. It all goes back to
that annoying little cable yoke again. Not only does it pull both brakearms
simultaneously, but it also splits the force you apply with the brake lever
evenly between each brake arm. So If you were to double the result from
my formula, you'd then have to divide by two the amount of force you initially
applied at the brake lever to get the net force being applied by each brakepad
to the rim. If you INSIST on writing the formula the other way, that's your
choice. I just don't want to hear about your brakepads delivering 300 foot-pounds
of force to both sides of the rim. I won't believe you.
"Joseph Bauder (NC)" wrote:
>
> On 5 Sep 1996, Kristan Roberge wrote:
> >
> > No you don't. you just need 50% more leverage, this can be achieved in
> > either the brake arms or the levers.
>
> Kristan,
> I've used Suntour Power Hangers that I got for cheap after they
> (tragically) went out of business. Got them 3 for $1. They're similar to
> the 'dale Force 40 system. I was wondering what would happen if they were
> added to a standard lever/v brake system. The cable routing and angles
> might be kind of strange; the Power Hanger (or Force 40) would probably
> sit way too low to come into the V brake at any reasonable angle . . .
> Well, it was a creative brain fart, at least . . .
>
You'd get a shitload of leverage, sneezing on the levers would probably
move the brake pads
What WOULD happen though is you'd have a hard time hooking up one
end of the power hanger because the V-brake's aren't setup for a conventional
straddle cable (there's no slot and groove in the arm for the barrel-end
cable to stick thru like on a regular canti. However you can get creative
with various small parts and make it work, also 5 minutes with a dremel
tool and the grinding stone and cutting wheel solves the groove problem.
Assuming your willing to do the modifications, your gonna end up with
a brake that will produce one-finger stops with your pinky... You
will have to play around with pad clearance a bit though, power-cam
setups require a tighter pad clearance. The reason they work to
offer more leverage is because unlike conventional straddle cable,
the yoke angle doesn't decrease when you pull the brake cable so the
leverage ratio of the cantilever changes less than it would with a
conventional setup. Most powercams are designed around a 45 degree yoke
angle, which is pretty good, so you keep this angle throughout the braking
action, but the straddle cable angle relative to the brake arm still changes,
meaning the leverage still drops off, just not as much as before. That's
why they are called leverage-enhancement devices.
Now BEFORE anyone says this won't work because of v-brakes requiring
a GREATER cable-pull... read the following... V-type brakes don't
really require the extra cable-pull because of the longer brake arms
but because your actuating BOTH arms with the same cable. If you want
the top of each cantilever arm to move 10mm with a linear-cable pull
arrangement you need 20mm of cable movement at the lever. But with a
straddle-cable arrangement, you only need 10mm of cable-pull at
the lever. Pulling both brake arms with one cable doubles the cable-pull
required for the same movement of the brake arm. Now the longer arms
themselves do require a bit more cable-pull to get the same amount pad
movement for a given amount of movement at the cantilever ends but
the lions share of the cable-pull increase comes from the linear
arrangement. If you combine the power-cam (or cannondale force-40)
or similar cable-arrangement with V-brakes you CAN get the system
to work, but lever feel will be on the mushy side as you'll be getting
a huge amount of leverage and modulation.
See... its not THAT crazy an idea...
"Duane Schweitzer" wrote:
>I have Onza brakes with Kool Stop pads on my bike and for the life of me,
>I can't get them to stop squeeling. I've tried just about everything in the
>book and still can't get the squeel out. Any info regarding how to stop it
>would be greatly appreciated!
Which model koolstops?!? The Eagleclaw I or IIs?!? Which color compound?!?
I've found the grey compounds to be the worst for noise and the
blacks to be the best.
In general, to fix squealing pads, the first thing you want to check is
the toe-in... and adjusting this with Boulder/Onza (which are the same
thing... Onza bought the design from Boulder Bicycles) brakes or
Westpine/Avid (also the same, the Tri-Align series is an evolved form
of a Westpine design licensed to Avid) brakes is ultra-simple to do
There is no standard toe-in for brake pads, some need it, some don't, but up
to 1-2mm is the norm for most (though winwood/scott-mathauser pads can
require more to silence them). You want the trailing edge of the brake pad,
that is the part closest to the front of the bike to contact the rim before
the leading edge of the pad. With Eagleclaw IIs this is easy to set as they
have a beak on the leading edge which is supposed to contact at the same time
as the trailing edge in order to clean dirt of
the rim sidewalls.
The second thing to check for squealing pads is to make sure your rim sidewalls
are clean and free of brakepad dust. Wipe them down with a soft cloth/paper
towel. I prefer to hold a piece of paper towel against the sidewall in one spot
and then spin the wheel. If you do this and then find alot of BLACK grime on the
paper towel, you've likely found one of the reasons for the squeal.
The third thing to check is to make sure your brake pads haven't glazed
over from the heat of braking. This is a problem with almost all pads
but some do it faster than others. V-brake pads are terrible when they
glaze over squealing as loud as winwood or mathauser pads do on annodized
rims... If the pads HAVE glazed over, you should roughen the surface
of the pads to restore braking power. You can use a metal file, sandpaper,
or even a bench sander...
The fouth thing you should check is to make sure the pads are contacting the
rim sidewall evenly, and not at an angle or diving under the rim towards the
spokes. Check for a lip or edge developing on the bottom of the brakepads for
this. This won't neccessarily produce a squeal, but it will reduce your
braking power.
Simon Boyce wrote...
>Feel I should have followed up more on this point you made. If it's true
>that the STX levers pull enough cable, why all the song and dance about
>upgrading to special Long Pull levers for V brakes? Do the STX levers
>pull more cable than fancier models?
The song and dance has to do with the fact that the long-pull levers ALSO have
less leverage. This reduces the risk some shmuck will do a faceplant the first
time he uses V-brakes and then sue shimano. Also most people are stubborn
morons who refuse to accept the fact that a FIRM brake lever does NOT mean
more powerful brakes and also refuse to ride a bike where the lever feel is so soft
and light that a six-year old you produce an ENDO with the brakes. "Obviously
if the lever feels soft then I'm not going to stop in time right?" is the attitude
of most people. Another reason for the increased cable pull has to do with wanting
extra pad clearance over the shimano reccommend 1-2mm.
Now without telling anyone the REAL reason (the lawsuit) behind the new levers,
shimano has managed to convince just about the entire bike community that
you have to have new levers to use the brakes. More money for shimano.
Now if Ben Capron (inventor of the Marinotive CheapTrick) managed to go 6 years
without long-pull, low-leverage brake levers, and in fact, convinced alot of
downhillers about the value of his side-pull cantilevers on their dual-suspension
bikes then odds are shimano is trying to pull a fast one (and succeeding).
Shitmano V-brakes have about a 3.0 leverage rate. That is to say, for every mm of
pad movement, the end (top) of the brake arm moves about 3mm. So if both brakes
are set with 2mm of pad clearance, you'll need 12mm (3 x 2mm = 6mm x 2 brakearms
= 12mm) of direct cable-pull JUST to get the pads to TOUCH the rim sidewalls. Now
since the pads will compress about a mm during the application of the brake force,
you'll need another 6mm of cable-pull to start to generate real stopping power.
That's 18mm total. So with your STX levers you have a 2mm reserve, and with XT
V-brake levers you have from 5mm to 8mm of reserve. Now with only 1mm of pad
clearance you'd only need 12mm to get real stopping power and now you'd have 8mm
of reserve.
So if you setup V's with 1mm of pad clearance you can use your STX levers without
any problems and also have more leverage than an V-brake lever would provide.
Any questions?
Leverage and Cable Pull :
Different brake levers have a different mechanical advantage. Generally a
lever with a higher cable pull will have also produce less leverage, and
vice versa. This is NOT always the case though, as some levers use a sliding
cable-pivot to achieve an initially low leverage and high cable pull and
then transitioning to a higher leverage and lower cable pull mode as the
lever is pulled closer to the handlebar/grips. Shimano servowave levers
are a perfect example of this. Total cable pull is close to 18mm and yet
they can generate more leverage than just about ANY lever on the market.
Meanwhile a Crystal Design Bad Finger lever about equals them in total
leverage, but only pulls 13mm of cable.
Sidepull Cantilevers :
Sidepull cantilevers are basically ANY model or brand name of long-arm
cantilever which is actuated without a seperate straddle cable or yoke
system from the side. They HAVE to be a long arm design as otherwise the
single brake cable would snag on the tire (Duh!) though not all long-arm
cantilevers use a sidepull operation (when you mix long-arms with a straddle
cable, the amount of leverage possible is just sick!). Some people call
this class of cantilevers "V-brakes" but this isn't really appropriate since
"V-brake" is a shimano trademark (and they didn't invent the concept in any
case) or linear-pull brakes or direct-pull brakes but I think sidepull is
the most accurate term. According to shimano, the minimum cable pull required
for their V-brakes is 23mm though most people I've met STILL set their pads
superclose and never use more than 10mm of the cablepull available in their
v-brake levers (sigh!). For that reason I provide the following list of brake
levers and their cable pull capabilities as well as lever length (in
fingers of operation - the new shimano V-brake levers are stupid short) and
weight (for a pair of levers).
Avid SD 2.0 : 12-19mm, 3 finger, 200g
Campagnolo Record O.R. : 22mm, 3 finger, 190g
Crystal Design Bad Finger : 13mm, 3 finger, 118g
DiaCompe MX-99 : 20mm, 2 finger, 157g
DiaCompe SS-5 Mk.II : 14mm, 3 finger, 138g
DiaCompe SS-7HB : 14.5mm, 2.5 finger, 178g
DiaCompe PC7S/PC11 : 16mm, 2.5 finger, 204g
Paul Component Love Levers : 14mm, 2 finger, 118g
Shimano Deore XT Servowaveø : 17.5mm, 2 finger, 250g
Shimano Deore XT SLR : 22mm, 2 finger, 270g
Shimano Deore LX STI : 20mm, 3 finger, 380g (with shifter pods)
Tektro RBP 366A : 19mm, 3 finger, 186g
ø Note : I had to "de-shifter" a pair of STI levers to get a set of seperate
servowave levers. Prior to the V-brake levers, shimano had not produced a set
of seperate brake levers after the old SLR design which was finally discontinued
after 1993. My "de-shiftered" levers involved cutting the shifter perches off
with a dremel cutting tool as well as machining out some slots in the clamps to
reduce weight further. I currently have several such sets of XT Servowave levers
in my collection of parts.
========================
MY TOP TEN BRAKE CHOICES
========================
#1 Westpine Scissors : Power/Modulation exceeds that possible with hydraulics
and Disc brakes. Leverage is infinitely adjustble thru the scissors linkage,
which allows the brake to be used with ANY lever regardless of cable-pull and
still provide one-finger stopping power. Advise caution when using these brakes
for the first time, I had had one-finger stopping for years and still endo'd the
first time I tried my scissors brake, super simple pad & spring adjustment
requiring a single 4mm allen key. High Price though and really intended for
suspension-applications only as the required mounting brace adds weight to an
otherwise superlight system, fortunetly braces are available that are both
stronger and stiffer than the stock braces on many popular suspension forks.
#2 Westpine Triple Alignment Cantilever : original version of the brake which
would become the Avid Tri-Align, super easy pad adjustment combined with long
verticle post arms provide for great power/modulation. No special bushings
required for the cantilever studs - as with the Tri-Align I - but very limited
production - I'm one of about 60 people WORLDWIDE to own any - makes finding
another set a slim possibility.
#3 Avid Tri-Align II, 74mm arm version : Why they offer a short-arm version
is beyond me... if your going to spend a couple hundred on a single brake,
you might as well get as much leverage out of the damn thing as possible.
Licensed and slimmed down version of the Westpine T.A.C. brake. 2/3rds the
weight but also alot more fragile and flexible looking. They do work just as
well though, and are alot more available but SUPER expensive.
#4 Marinotive CheapTrick : Advertised as the original production v-brake,
although this isn't strictly true. The original version is now known as the
stoplight as calling something that cost over $100 US per wheel "cheap" was
a bit excessive. The new version was introduced in '93 and is in fact, much
cheaper. At about $80 US per wheel they are more expensive than many of the
Asian versions of the sidepull cantilever brakes but they are also THE
lightest cantilever brake around (58g per wheel, without pads) which gives
the alot more bang for buck than shimano offers. No fancy linkages or
bushings to wear out, easy pad adjustment (standard threaded pad hardware,
koolstop pads) and spring-adjustment (little mentioned fact : WTB patented
the spring-design used by Marinotive, Shimano V's, and many other
sidepull cantilever designs BUT all but Shimano are also known to have WTB's
permission to use the spring-design). With a decent set of threaded brake
pads (Koolstop or Mathauser) a complete brake around 90-100g is gives them
a real edge over XTR V-brakes at about 180g per wheel.
#5 Magura Hydraulic : Great power and modulation, and very easy pad adjustment
though it does require a bit of practice getting it right. Contrary to what is
advertised (shimano claims the same thing for their V-brakes), some Toe-In of
the pads can be required depending on the specific rim combination your using.
Fortunetly this is fairly easy to set and unlike shimano, lots of pad clearance
and having great power/modulations are not mutually exclusive terms. However the
brakes are heavy, and bleeding the hydraulic lines can be a bit of a chore for
a first-timer. Total system weight (levers, brakes, housing, oil) is roughly two
pounds, or about a pound more than Marinotive CheapTrick brakes, lightweight
high-leverage levers, and cables/housing which work out around the same price
and offer as much power/modulation but not as much pad clearance.
#6 Marinotive Stoplight : This design used to be the called the cheaptrick,
but its excessive use of Titanium made it anything but cheap. Major differences
between the Stoplight and the current cheap trick is the brake arm design. Ti
vertical post on the Stoplight and an extruded aluminum billet on the Cheaptrick.
#7 Gravity Research PipeDreams : Easy pad adjustment, though pad-contact angle
depends on arm position and pad distance from rim, lightweight and good arm
length, a bit expensive though. Vertical post design uses the now popular
shuttle-style pad holder that allows seperate pad adjustments of height/toe-in
and pad-distance/angle. This shuttle-style pad adjustment feature was actually
invented/patented by Marinotive around '86, but the patent was later given up.
#8 Boulder Quick-Adjust / Onza H.O. : Technically the same brake, designed and
patented by Boulder Bicycles but later sold to Onza. The Boulder version differed
in the use of titanium bolts to keep the weight down. Super easy pad adjustment
but the arm length tends to be on the short side and the brakes encourage setup
like semi-wide profile cantilevers common to the late 80s. The Boulder version
was expensive but the Onza version, being made in greater numbers and using
steel bolts was much cheaper. Due to the short arms, gettting great power and
modulation was ultimately dependant on either high-leverage brake levers or a
low-straddle cable angle. Onza offered a longer-arm version for the front but
really this version should have been standard for both front and back. Problem
is the semi-wide setup style results in problems with heel clearance on small
frames.
#9 Crystal Design PowerBrakes : Lightweight, longer arms than most low-profile
canti's, a bit pricey though, lotsa color choices and easy to drop the weight
further since the stock hardware is steel, better spring-adjustment than most
canti's also. The Powerbrake II version, which is their sidepull model has
taller brakearms than the shimano V-brakes, uses regular post-type brakepads,
and is about 30g lighter per wheel than the V's.
#10 Deore LX/DX/XT/XTR Low-Profile :Hey, they work well, can be adjusted for a
variety of power/modulation thanks to the straddle cable, and don't have any
bushings/pivots/linkages that are prone to wearing out, and pad setup isn't
that hard to master, and they don't cost an arm and a leg.
And for those wondering where I rank V-brakes...
#11 M600 V-brakes (STX-RC/LX/DX) : Thanks to the loss of the linkage, these
brakes should help save shimano's reputation as the maintenance issues have
now been reduced to the shitty pad life. I do prefer the DX version as they
get a nicer finish and have more pad-height adjustibility. Since the pads
are still so thin, your more likely to be replacing the pads than ever adjusting
for pad-wear. Price has come down as well (well, except for the DX version
which costs about as much as the XT's but do sell as a kit, rear brake &
brake lever).
#12 Shimano U-brakes (Exage & Deore models) : Ever wonder why shimano picked
the name V-brake? Because their previous "ultimate" brake was called the
U-brake. Many people feel the U-brake was one of the worst designs of all
time but in fact its actually rather nice, with LONG arms that are curved
to improve heel clearance. The power & modulation can easily equal or exceed
that of V-brakes, but they have 3 major strikes against them. #1 is the
excessive weight (about 300g per wheel with pads), #2 is the need for
different brake studs (meaning a bike equipped with U-brakes CANNOT use
cantilevers), and #3 is the fact that the most popular mounting location for
many years (under the chainstays) was a great place to attract mud, which
quickly jammed the brake. Also the return-spring adjustment is dismal (but
all shimano brakes suffer from that problem) and the pad choice is limited
to thread-on types. I still have a U-brake on one of my bikes though and its
setup for 1-finger stopping power.
#13 (and slipping) Deore XT/XTR V-Brakes : Bringing long-arm, linear-pull brakes
to the masses. Not Originally intended as a super-powerful brake but simple as
a means of offering an off-the-shelf brake for OEM that solves the cable-routing
problems inherent in many rear suspension frames... finicky linkages/bushings
though, and pad life doesn't live up to shimano's claims, also the power of
mixing v-brakes and v-brake levers isn't any better than stock canti's setup
with a low straddle cable and stock levers but the pricetag is substantially
higher.
