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    Senior Member meanwhile's Avatar
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    Cantilver Brake FAQ

    I've filled in more time with my netbook while waiting for trains etc, and this is the result. As requested it now includes other sorts of brakes than cantis - but I really don't know much about these, so more contributions are needed. Hints about discs and comments about v-brake modulation and v's vs mini-v's would be especially useful.




    The Laws Of Brake
    (With special attention to cantilevers.)

    I. The Basics

    1. Fit good good brake pads
    Your brake can't slow down the tyre better than it can grip the rim. Kool Stop and Swiss Stop pads are specially favoured by cross riders. Both brands are colour coded: for riding in the wet with aluminium rims you need Kool Stop Pink (aka Salmon) or Swiss Stop Green pads.

    2. Keep your rims clean
    A green Scotchbrite pad works well for this. Dirty rims brake poorly and may wear out themselves and your pads more quickly.

    3. Keep your pads clean
    Give the inner surface a rub with something abrasive occasionally. (Making sure that you don't leave any abrasive particles behind!) This will get rid of particles of dirt and metal that will, again, reduce brake performance and increase wear.

    4. Make sure that your cable path is a good one - and that your cables are too
    Unnecessary kinks and bends cause friction, eating up "squeeze". sheldon brown
    And never substitute gear cable for brake cable - it isn't strong enough.

    5. Lube your cable inners as needed
    If you have fancy expensive cables, check the manufacturer's recommendations first. Otherwise see:

    http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3824
    http://www.bikeradar.com/gear/articl...ur-bike-18259/

    I like GT85 as cable lube.

    6. Know how to use your brakes
    - Use your front brake aggressively. Once a tyre exceeds its traction limit in braking (or turning) then it will skid. And when you brake the back wheel loses traction - but the front wheel gains it. So strong braking has to come from the front wheel. Keep your arms "strong" but not rigid - i.e. don't let your weight move forwards but do allow the bars the freedom to let your bike make the small automatic steering corrections built into its geometry, and which are needed to keep it upright. (You do know that if you lock your arms and wrists while holding the bars that your bike will crash? Weird, isn' it?)

    - Learn to hold your brakes at the edge that exists just before a skid. It is here that braking will be greatest. This will require a different amount of squeeze for each brake and the amount and balance of squeeze will depend on surface and slope. You have to learn to feel the bike's balance the skid point - especially for the rear. The only way to do this is the Carnegie Hall method - practice, practice, practice!

    - The third secret of braking is that braking and steering both use up traction. You can do both, but not to the same extent you could do either alone. Again, practice.


    II. Mechanical Advantage and Pull

    1. Mechanical advantage and the problem of pull
    You almost certainly know what leverage is. Mechanical advantage (MA) is a generalization of this. It can be achieved via levers, pulleys, gear systems, hydraulics and other means. It is simply the amplification of exerted force. If a system has an MA of two then twice as much force is exerted as put in.

    There is a cost for mechanical advantage. When a lever doubles output force then the input force must travel twice the distance than it would if the two forces were equal. Imagine a lever that doubles MA: the input side of the lever must be made twice as long as the output side. So raising the output side one inch will require moving the input side two inches.

    This same rule applies to all mechanical systems for increasing MA: Twice as much force, twice as much pull. Three times as much force, three times as much pull - etc, until infinity.

    There are two consequences to this:

    - Brakes and levers have to have matching pull, or the pads won't move far enough or will be too stiff to press really hard against the rims. Standard road brake drop bar levers are NOT pull compatible with regular v-brakes or most disc brakes, although there are ways of getting around this. See the section on each brake type.

    - MA and pull are inevitably traded off against each other. People often mistake MA for braking power but it is only of part of it. Yes, if MA is too low then it won't be able to overcome the resistance of the brake pads - acting like rubber springs - to being squeezed against the rims. But if MA is set very high and pull very low then the pad will be squashed easily - but not very deeply! This means that little braking force will be exerted. Good braking requires good MA and adequate pull.

    Good pull is also needed for clearance between rims and brake pads - if maximum pull is less than the clearance you have set, the pads won't even touch the rim when you bottom out the levers. The amount of clearance you need depends on the track you are riding. Smooth roads need very little clearance, but a muddy trail will coat your tyre with clumps of mud that will smash against your pads slowing you down.

    2. Single speeds and bar con bikes can get easy compatibility by using v-brake road levers
    Special v-brake compatible drop bar levers are available. These will work directly with standard v-brakes and disc brakes. These levers do NOT include shifter controllers, but if you're riding singlespeed or with bar cons they may be a good choice.


    III. Cantilevers
    Cantilevers - aka "cantis" - are the standard cross brake for good reason. They allow wide tyre clearance and can be easily adjusted to give different combinations of MA, pull and clearance as needed for conditions - so on a dry course clearance can be cut to a minimum and power to a maximum, and on a muddy course clearance can be increased at the cost of full-on braking power. Many people also think that cantis give the best modulation (the ability to apply controlled amounts of braking) of any rim brake.

    However cantis can cause problems. People complain of low power, squealing brakes, and even dangerously destabilizing fork judder. All these problems can be easily and cheaply cured, but most people - including the mechanics in most all bike shops - don't know how. So read on!

    1. The ultimate reference and other useful links
    The definitive analysis and reference on Mechanical Advantage and tuning:

    http://www.circleacycles.com/cantile...i-geometry.pdf

    Accompanying MA calculator app:

    http://www.circleacycles.com/cantilevers/

    Squeal and judder:

    http://velonews.competitor.com/2010/...o-cross_101807


    2. Types of cantilever
    Cantilevers can be classed in several types according to the angle of the arm that holds the cable.

    Narrow profile cantilevers (aka low profile) a
    ...Are as you'd expect - narrow! Their arms reach up and hardly go the side at all.

    - Easy to fit the rear where a brake with protruding arms might catch the riders heels while he pedals.

    - Very sensitive to set-up and are the least capable of getting good mud clearance while achieving good power.

    - Getting good MA can require a very low straddle cable. This can interfere with a mudguard - or even with a tyre if your bike is set-up as a monster crosser.

    Medium cantis
    ...Are between the narrows and wides.They're not widely favoured at the moment - a wide at the front and a narrow at the back is more common.

    Wide profile cantis (aka high profile)
    ...Have arms that are more or less horizontal.

    - Best ability to be set for good mud clearance while keeping decent braking power and are very popular as front brakes.

    - Straddle cables can be set relatively high and MA will still be good

    - Can stick out too much to be a good rear brake - they may catch your heel while pedalling or your shoulder while carrying your bike.

    Super wide cantis
    ...Have arms that slope downwards. These are now historical curiosities only but should still be mentioned as the straddle cable tuning guide that follows won't work for them.

    4. Adjusting power and pull: straddle cables and tuning
    - The main way to tune your cantis is to adjust the length and height of your straddle cable. Shortening the straddle cable will give you more mechanical advantage but yield less pad movement for the same lever movement. As always, you need to find your personal preference. (Lowering the yoke/ shortening the straddle cable to increase MA always works for all canti types except super-wides.)

    - Shimano cantis have pre-set straddle cables aka "z-wires". In this set-up the main brake cable runs directly to one brake arm and a yoke with a short cable of fixed length clips on to activate the other. These are known as z-wires and come in various lengths. Searching for "tektro z-wires" can help find them on the net.

    - Other cantis come with a more tuneable straddle cable that runs from one arm to another. This cable runs through a yoke or "cable hanger" that attaches to the main brake cable. Shimano brakes can be converted to this set-up with a few minutes work.

    - Mild warning: in theory, your main front brake cable can snap, in which case a non z-wire straddle will flop down and catch in the tread of your tyre, causing a very sudden stop. You can prevent this by checking your brake cable for fraying or by installing something to stop the straddle from falling that far.

    - If you want maximum braking power then tune so that your pads will be set for the smallest amount of clearance that is tolerable given the terrain you are riding.

    - My experience is that adding a fork mounted hanger will improve power and modulation. This makes sense - the less unnecessary flex there is a cable system, the better it should be at transmitting force.

    5. Squeal and judder
    See http://velonews.competitor.com/2010/...o-cross_101807

    Judder - and sometimes squealing (but this has other causes too) - is caused when your fork flexes during braking. As the fork flexes it can alter brake cable tension - which in turn alters how hard the bike is braking, which then alters the degree to which the fork has flexed - and around and around the cycle goes.

    The cure is easy: stop either the fork from flexing (there are ultra rigid forks that don't flex - this is an easy solution but not a cheap one!) or stop the cable from flexing when the fork does by fitting a fork mounted cantilever hanger (aka FMCH from now on) instead of - or as well as - the more usual stem mounted hanger.

    Fork Mounted Cable Hangers
    - These need a hole in the fork crown to mount. If the crown lacks such a hole and is metal then you can (carefully) drill one. But do NOT ever drill into a carbon fibre fork crown!

    - Some carbon forks come with a built-in hanger.

    - If you have problems finding a hanger, order or Internet search for the Kona Design Front Hanger BP1272F

    - A hanger can get in the way of running a front fender/mudguard. This may be less of a problem with a wide canti as it will let you use a higher yoke position which may let you route the straddle around the outside of the fender. Or you could use an MTB style fender that clips on to your down tube instead of the fork.

    If you can't mount an FMCH and don't want to run v-brakes or buy a new fork
    Try lots of toe-in, a very tight headset, and even trimming your brake pads down.

    6. Common mistakes
    Some people tune so that their cantis feel hard and definite. This is a mistake. Cantis should feel somewhat soft and rubbery, from the feedback of the brakepad being squashed against the rim. Cantis only feel hard if MA is set too low to squash the pad. However, not all soft cantis are correctly tuned! A soft canti may have good MA but too little movement.

    Some people believe that the straddle cable should make a right angle with a line from the point where the cable attaches to the brake arm to the point where the pads will touch the rim. This is wrong. See "The Ultimate Reference" to understand why.

    7. Recommended brakes
    Remember: don't judge a cantilever as lacking power until you have installed a decent pad, tuned the straddle cable, and if necessary fitted a fork mounted hanger! Almost all cantilevers can be transformed this way and even the best cantilevers will usually perform poorly without these tweaks.

    - The Tektro CR520 & CR720 are reasonably priced and very effective wide cantis.

    - Shimano makes a number of good narrow cantis at a range of prices.

    - The Avid Shorty Ultimate, Paul's Touring and Paul's Retro are all well-regarded high-end brakes . Although it is arguable that a canti (which is after all nothing but a lever and a return spring) is so simple a device that there is little point in paying a high price.


    IV. Mini V-Brakes
    Mini-v brakes sacrifice the adjustability, clearance and (perhaps - opinions vary) modulation of cantis for easier set-up and a lack of fork judder. They may be a good choice for you if your bike doesn't have to race through mud very often. Because they are pull compatible with road levers they can be fitted to a crosser without any special tricks.

    Hints
    If your mini-v's squeal then read the Cantilever section and use the tactics discuss there - toe-in, a tight headeset, and a fork mounted hanger.

    Advantages
    Easy set up. No risk of judder.

    Disadvantages
    Poor clearance; questionable modulation.

    Recommended brakes
    Tektro RX5 - 85mm arm length
    Tektro RX6 - 90mm arm length, so should give slight more MA and less modulation
    TRP CX9 - 90mm arm length. TRP = Tektro Racing Products... I suspect this will behave almost identically to the RX6, despite costing 4 times as much!


    V. Fullsize V-Brakes
    Fullsize v's have all the characteristics of mini-v's except pull compatibility. This can be provided using a "Travel Agent" or "V-Daptor". See:

    http://www.phred.org/~alex/bikes/brakes.html.

    If you decide to use a v-brake and adaptor, consider using it only at the front and keeping a canti at the back: most braking (and virtually all canti braking problems) happens at the front, and adaptors at the back may tend to clog with mud.

    Advantages
    Easy set up. No risk of judder.

    Disadvantages
    Poor clearance; need an adaptor; questionable modulation. Why not use a mini-v?

    Hints
    If your v's squeal then read the Cantilever section and use the tactics discuss there - toe-in, a tight headeset, and a fork mounted hanger.

    Recommended brakes
    The Avid Single Digit 7 is considered an all-time classic.


    VI. Disc Brakes
    Disc brakes require special mounts on the fork and frame and special wheels. They also add weight and may be harder to service than rim brakes. However they are powerful, modulate well, ignore mud on the rim and make clearance a non-issue. Standard disc brakes are not compatible with road levers. However you should be able to fix this using one of the adaptors made for v-brakes. And there are special road brake compatible disc brakes too.

    Road lever compatible discs
    These exist. Check carefully what you are buying!

    Adaptors can be used with mechanical MTB discs
    Treat as with fullsize v-brakes.

    It can be worth fitting a disc fork even if your frame can't take a disc at the back.
    Most of your braking happens at the front, so most of the benefit of discs comes from fitting a disc fork.

    A frame builder maybe able to add disc mounts to a metal frame.
    Ask one!

    Hydraulic adaptor
    You might be able to get hardware that lets you use your mechanical road levers with hydraulic MTB brakes:

    http://www.bikeradar.com/news/articl...nverter-27723/


    VII. Interrupter aka cross levers
    These handy things go on the flat part of your bar to give you an on-the-tops braking position.

    - If fitted correctly they shouldn't reduce power

    - They won't have a problem working with v-brakes if an adaptor has been fitted

    - Getting the cable path right so that power and modulation aren't reduce can be tricky. Using compressionless braking cable may help. Do not confuse this with the more common compressionless gear cable - this is not strong enough for use with brakes.


    VIII. Brake boosters
    Powerful rim brakes can cause their mounts to flex reducing power and modulation. Brake boosters are U-shaped pieces of metal or carbon fibre that arch over the wheel to join the mounts together, reinforcing them. Much more popular among mountain bikers.


    IX Problem Solver
    When multiple solutions exist I've listed the cheaper ones first. I've recommended the CR720 and RX5 when a specific brake seemed useful not because either is a favourite of mine but because they are almost universally liked and cost very little.

    If your brakes are cantilevers and they aren't powerful enough
    - Learn to use your front brake aggressively, clean your pads and rims, fit better brake pads, check the cable path is good, tune the straddle cable, fit a fork mounted brake hanger
    - Fit a Tektro CR720 to the front and adjust the straddle again
    - Fit a mini-v brake to the front - probably a Tektro RX5

    If your brakes are NOT cantilevers and they aren't powerful enough
    - Learn to use your front brake aggressively, clean your pads and rims, fit better brake pads, check the cable path is good, lower the straddle cable, fit a fork mounted brake hanger
    - If you are using a full-size v-brake make sure you are using the pull adaptor correctly

    If your brakes squeal or cause fork judder
    - Increase brake pad toe-in, fit a fork mounted hanger, shorten your brake pads, tighten your headset
    - Fit a mini-v brake to the front - probably a Tektro RX5

    If you need more pad-rim clearance than your current brake will give you
    - Fit a wide profile cantilever, probably a Tektro CR720

    --------------------------------
    My thanks to everyone who has contributed so far, either in this thread or in the previous ones that I mined. I'll add names of contributors in the next edit, really!
    Last edited by meanwhile; 04-19-11 at 03:54 PM.

  2. #2
    Senior Member meanwhile's Avatar
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    The above is my attempt at creating something that can be used as a sticky. Please help, especially if you can simplify or clarify the tuning instructions!

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    Most people use their cross bikes for riding other than racing. I'm one of them. Because I live in a place that rains nearly 7 months out of the year, I require fenders. With the fork mounted hanger you can't mount fenders.... This was a no go for me.
    Demented internet tail wagging imbicile.

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    Unique Vintage Steel cuda2k's Avatar
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    A thanks to meanwhile for getting this FAQ kicked off. Going to sticky this thread for easy reference.
    [CENTER][URL="http://VeloBase.com"][IMG]http://velobase.com/App_Themes/VeloBase2_blue/Images/VeloBase2TitleCampagnolo.jpg[/IMG][/URL][/CENTER]
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  5. #5
    Team Water Andy_K's Avatar
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    This is a good start. Thanks for taking the initiative!

    I think you're over-emphasizing the fork-mounted cable hanger. That's a great solution (when possible) for fork shudder, but it only helps poor braking performance if the poor braking performance is caused by fork shudder. It might incidentally help other problems by forcing you to lower your straddle cable, but it seems better to address that directly.

    It might be worth adding a section on Z-link wires, as there are several lengths available and choosing among them can help improve braking.

    You could expand a lot on the discussion of V-brakes and mini-V brakes, in which case this thread should be renamed something more generic. A discussion of disc brakes is probably also worth having.

    What you have about the trade-offs between mechanical advantage and pad travel is good, but I'd like to see it given more emphasis and perhaps expanded upon slightly.

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    Senior Member meanwhile's Avatar
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    Quote Originally Posted by Andy_K View Post
    This is a good start. Thanks for taking the initiative!

    I think you're over-emphasizing the fork-mounted cable hanger. That's a great solution (when possible) for fork shudder, but it only helps poor braking performance if the poor braking performance is caused by fork shudder. It might incidentally help other problems by forcing you to lower your straddle cable, but it seems better to address that directly.
    Interesting point! In response:

    1. They're cheap and level the playing field for tuning, never do any harm, and cantis that don't squeal without hangers are very rare - if they exist

    And, more importantly -

    2. I added a hanger to a bike that braked superbly (squealed a bit, shuddered not at all) - an '88 Kona Lava Dome with a fork like the handle of a high tech battle axe. Braking went from A to A++ - silent, wonderful modulation, effortless power. If I'd ridden the bikewithout knowing what brakes it had I'd have sworn that they were hydraulic discs.

    So I think that if a hanger can be added then it should be added. The only exception I'd make is for a bike that is braking without any squealing at all. Squealing is produced by vibration that a fork mounted hanger can remove, and this can transform braking.

    It might be worth adding a section on Z-link wires, as there are several lengths available and choosing among them can help improve braking.
    Well volunteered!

    You could expand a lot on the discussion of V-brakes and mini-V brakes, in which case this thread should be renamed something more generic. A discussion of disc brakes is probably also worth having.
    Again, I think these ideas are *very* worthwhile but need someone else to do them. Partly because I have done enough to satisfy myself, partly because I've never used vees and a TA, or mini-vees, or maintained a disc brake bike. Cantis I can speak of from experience.

    What you have about the trade-offs between mechanical advantage and pad travel is good, but I'd like to see it given more emphasis and perhaps expanded upon slightly.
    Interesting again - I was worried I'd been too detailed.

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    Senior Member meanwhile's Avatar
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    Quote Originally Posted by knobster View Post
    Most people use their cross bikes for riding other than racing. I'm one of them. Because I live in a place that rains nearly 7 months out of the year, I require fenders. With the fork mounted hanger you can't mount fenders.... This was a no go for me.
    Excellent point! Weirdly, a lot of English people don't bother putting fenders on our bikes.

    Has anyone tried Crud Catchers? That's what I'm going to do this year - use the sort of front fender goes on the down tube. (I've never liked the modulation on vees, so I'm willing to make a strong effort to avoid them.) And you can have a bar mounted fender as an extra if you want to look like a Downhill MTB Badass:

    1244187912635-th6ln54z5xhj-280-75.jpg

    What do you think? Too silly???

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    That's an option...

    I ended up selling my canti/v-brake only bike and picked up a titanium Airborne with disc brakes. No problems anymore...
    Demented internet tail wagging imbicile.

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    Team Water Andy_K's Avatar
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    Quote Originally Posted by meanwhile View Post
    2. I added a hanger to a bike that braked superbly (squealed a bit, shuddered not at all) - an '88 Kona Lava Dome with a fork like the handle of a high tech battle axe. Braking went from A to A++ - silent, wonderful modulation, effortless power. If I'd ridden the bikewithout knowing what brakes it had I'd have sworn that they were hydraulic discs.
    Do you have any explanation, apart from yoke height, for why adding a fork-mounted cable hanger would increase braking power?

    I've never had a problem with squealing with my stem mounted hangers. Maybe I've just been lucky.

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    Senior Member meanwhile's Avatar
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    Quote Originally Posted by Andy_K View Post
    Do you have any explanation, apart from yoke height, for why adding a fork-mounted cable hanger would increase braking power?

    I've never had a problem with squealing with my stem mounted hangers. Maybe I've just been lucky.
    Squealing has the same root as shudder - it's just a lesser version of the same problem. Or even exactly the same in magnitude but mitigated by a tighter headset. The brakes go on, the fork flexes, the cable flexes - the brakes go off. The fork flex back, the brakes go on. Obviously you lose braking power and modulation during this. A fork mounted hanger minimizes cable flex, so when the fork goes back the cable stays tight. So the brake stays on and fork stays (minutely) back.

    And, yes, you've been lucky. All my canti bikes have squealed a bit, although all of them except the crosser have had excellent braking power without a hanger. (The crosser I'd rate as so-so.)

    The question everyone now wants to ask: what bike/fork/brake do you have???

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    Senior Member meanwhile's Avatar
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    I'll also add a summary of the recent interrupter brakes thread...

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    If you don't like the "stopping power" of your cantis, first thing to try is shortening your straddle cable (or link wire) as much as possible.

    This is a cool applet:
    http://www.circleacycles.com/cantilevers/

    It shows that as you lower the yoke height (i.e. shorten the straddle cable) you increase mechanical advantage. It also shows that low-profile cantis have more mechanical advantage than old-school Mafac-style.

    Remember that increasing mechanical advantage means reducing the clearance from pad to rim.

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    Here's how to route your cables when you have a short drop from stem to cable hanger:


    If you don't have top-mount levers, you can cram it under the stem with a couple short bends, but with top-mounts, the cable housing needs to be able to move.

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    Senior Member GrayJay's Avatar
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    Quote Originally Posted by flargle View Post
    If you don't like the "stopping power" of your cantis, first thing to try is shortening your straddle cable (or link wire) as much as possible.

    This is a cool applet:
    http://www.circleacycles.com/cantilevers/

    It shows that as you lower the yoke height (i.e. shorten the straddle cable) you increase mechanical advantage. It also shows that low-profile cantis have more mechanical advantage than old-school Mafac-style.

    Remember that increasing mechanical advantage means reducing the clearance from pad to rim.
    It is important to note that lowering yoke height only increases Mechanical Advantage (MA) if the cantilver alfa angle is < 90 (medium or low profile). Note that Shedon and Circleacycles confusingly define cantilever angle differently, I am using the circleacucle definition, makes more sense to me. Downside of medium or low profile cantilevers is that during swing of the caliper, they start with a high MA and as the yoke rises the MA decreases. Exactly the opposite behavior is much more desireable, so that there is more initial movement to quickly swing the pad closer to the rim and then ramp up MA once the pad is in contact with the rim. Having excessivly high MA is not necessily desireable for a cross bike! Result is an overly strong brake that can more easily lockup the wheel with little ability to modulate the braking force at the lever. As flargle noted, High MA also dictates that the pads must be setup close to the rim so will be less tolerant to bent rims, broken spokes and mud clearance. Tune for only as much MA as you need.

    If alfa angle exactly = 90, you get the original linear pull brake, the MA is entirely uneffected by yoke height setting.

    If alfa angle > 90 (super wide profile) you get progressive brake curve, raising the yoke actually increases the MA. Unfortunatly, such configurations has inherently low MA however so you may need to pair them with levers with very high MA or run the cable through a pulley at the yoke pivot and back up to a fixed anchor to double the MA (and 1/2 the travel) of the system.
    Last edited by GrayJay; 03-30-11 at 07:03 PM.

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    Team Water Andy_K's Avatar
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    Quote Originally Posted by meanwhile View Post
    Well volunteered!
    Fair enough.


    Z-link wires

    Several common cantilever brakes use link wires instead of the traditional separate yokes and straddle cables. Mechanically, the link wire functions exactly the same as the yoke and straddle cable except that to change the yoke height you have to switch link wires. While this limits adjustability somewhat, it also simplies set up.

    Link wires are available in five sizes. Your LBS may recommend switching to a yoke and straddle cable setup rather than switching link wire sizes. That will work, but if you prefer the simplicity of link wires the LBS should be able to order them. Link wires are also available from several online retaillers. You will find "Tektro Z Link Wire" to be a reliable search term to find them.

    As with other cantilever setups, lowering the effective yoke position will give you more mechanical advantage (raw braking power) but will yield less pad movement relative to the lever movement. As always, you need to find your personal balance preference. In terms of link wires the shorter the published "size" of the wire, the lower the effective yoke position. Therefore, a 63 mm link wire provides the greatest mechanical advantage, while a 106 mm link wire will allow the best mud clearance.

    See also: http://sheldonbrown.com/canti-trad.html#yoke

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    I always get confused by explanations of mechanical advantage- I get the concept but the whole issue of lever feel I'm not sure on.

    "The more mechanical advantage you have, the closer the brake shoes will be to the rim at their rest position."

    "A hard, crisp feel to the brakes on a bicycle may be a sign that the brakes don't have much mechanical advantage"

    I have low profile cantis and the only way I get any feel out of STI levers is when I have the pads close to the rim and when the pads don't have to travel far. When they're further away from the rim I almost bottom out on the levers getting the pads to touch the rim. They certainly don't feel like road brakes, but the more MA I have the more feel I have. Granted I don't have much mud clearance but this wasn't issue last year in New England.

    Perhaps, It's the brakes I have, there no-name cheapies that came with an entry level cross bike. I play to upgrade them soon because they're a pain in the ass and they're almost past there time. I plan on getting TRP Euros or frog legs.

    I learned to tune my brakes just by playing with them a lot and finding the balance of lever feel vs. braking power, it took a while but now it's fairly easy for me to find that balance.

    Also anyone have any thoughts on barrel adjusters? Are they helpful or do they not do much?

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    Senior Member meanwhile's Avatar
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    Quote Originally Posted by GrayJay View Post
    It is important to note that lowering yoke height only increases Mechanical Advantage (MA) if the cantilver alfa angle is < 90 (medium or low profile).
    Not QUITE - even regular wide cantis have alpha < 90. Only super-wide cantis, no longer made(?) go beyond this. Alpha is only > 90 when the cable attachment point is lower than the pivot. So any modern brake that people think of as wide - the Paul Retro, the CR720 - will still get more powerful with a lower straddle.

    Note that Shedon and Circleacycles confusingly define cantilever angle differently, I am using the circleacucle definition, makes more sense to me. Downside of medium or low profile cantilevers is that during swing of the caliper, they start with a high MA and as the yoke rises the MA decreases. Exactly the opposite behavior is much more desireable, so that there is more initial movement to quickly swing the pad closer to the rim and then ramp up MA once the pad is in contact with the rim. Having excessivly high MA is not necessily desireable for a cross bike! Result is an overly strong brake that can more easily lockup the wheel with little ability to modulate the braking force at the lever. As flargle noted, High MA also dictates that the pads must be setup close to the rim so will be less tolerant to bent rims, broken spokes and mud clearance. Tune for only as much MA as you need.

    If alfa angle exactly = 90, you get the original linear pull brake, the MA is entirely uneffected by yoke height setting.

    If alfa angle > 90 (super wide profile) you get progressive brake curve, raising the yoke actually increases the MA. Unfortunatly, such configurations has inherently low MA however so you may need to pair them with levers with very high MA or run the cable through a pulley at the yoke pivot and back up to a fixed anchor to double the MA (and 1/2 the travel) of the system.
    +1

    BUT - can you even find alpha > 90 cantis anymore???

    With the addition that I prefer the standard behaviour of cantis re MA - ie that it falls as the squeeze increases. This means that the brake becomes more sensitive and controllable as you approach the point where your wheels will lock, making it easier to hold the bike just beneath that point.
    Last edited by meanwhile; 04-15-11 at 08:11 AM.

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    Two odd coincidences:

    - I live near one of the best bike shops in the UK, Ron Spencers. They outfit most of the racers in this area and are one of the main places to go for a crosser when cross racing season starts.

    - I had to take my bike there for emergency surgery (something nasty happened to the stem expander bolt) and the ultra-experienced mechanic told me he could tune the squealing cantis to complete silence, other than the rub or rubber on the rim, without a fork mounted hanger.

    He did! I'm still trying to work out how. But one obvious change he made was to rotate the pads so that they were long sides forwards instead of back. But this can't be everything because I'm sure I've tried that myself. I'll take a photo and very careful measurements then play around when I have time...

    Modulation and power are very, very good - not quite as good as my Lava Dome MTB with its fork mounted hanger, but it also has a much beefier stem, possibly stiffer cant mounts, different pads, etc.

    Edited to add:
    I'm less impressed now that I have new and grippier tyres on my crosser. The brakes could put the old tyres into a braking skid on a slope, but not the new ones. As much grip as the tyres have I don't think they're better than the Lava Dome's: I'll order a fork mounted hanger and finish the job myself.
    Last edited by meanwhile; 04-06-11 at 03:49 PM.

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    Quote Originally Posted by Andy_K View Post
    Fair enough.
    Nicely done! Thanks!

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    On my 2002 Jamis Nova I run Planet Bike fenders with Conti Gators in 28 witha tektro fork mounted cable hanger and CR 720s. I also use an inline barrel adjuster above the hanger.


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    Quote Originally Posted by meanwhile View Post
    It is defintily helpfull to read the arcticle through several times and give it some thought, lots of great info. Note that in Figure 3, as the brakes are applied the arm swing angle goes from large angle to smaller angle (travel along the graph from right to left). This nicely demonstrates how the wide and ultra wide setups have progressive mechanical advantage and the narrow angle cantilevers have pretty severe regressive mechanical advantage change through their movement range.

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    Quote Originally Posted by meanwhile View Post
    I love that article and the corresponding visual calculator: http://www.circleacycles.com/cantilevers/

    In my mind, it has replaced Sheldon Brown as the standard Internet resource for cantilever setup. It would be great if we could get people to measure their brakes and report the relevant numbers for use in the visual calculator. I would also be curious to hear what MA works best for various people.

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    Senior Member meanwhile's Avatar
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    Quote Originally Posted by Andy_K View Post
    I love that article and the corresponding visual calculator: http://www.circleacycles.com/cantilevers/

    In my mind, it has replaced Sheldon Brown as the standard Internet resource for cantilever setup. It would be great if we could get people to measure their brakes and report the relevant numbers for use in the visual calculator. I would also be curious to hear what MA works best for various people.
    Yes - I'd especially like figures for the Avid Shorty Ultimate in both positions (it flips through what looks like 90 degrees.)

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