genericbikedude

Theoretical question: are cantilever brakes any stronger than caliper brakes? Pull ratio is in the lever, and both brakes work with the same lever, though one can up the mech advantage with some canti cable setups, but also with some calipers, notably mafac's. Also, pads on cantis are usually larger, leading to better braking (right?).

Do canti's give more stopping power, holding cable adjustment on the canti's constant? Or are they just for better clearance for fat tires and fenders?

I'm thinking of starting a new bike project, but I dislike the idea of relying on calipers on anything besides a fixie. Is this irrational? I often carry a heavy mess bag with old heavy laptop and tons of books, and I'm thinking of looking for an old 531ish road frome to build up, maybe with a swapped fork for front cantis.

HillRider

Modern double pivot calipers are the equal of cantis in practical stopping power, i.e. the hand effort needed to slow or control speed at the same rate is about the same. Both are more than able to lock up both wheels so their "ultimate" power is also the same.

Cantis allow any width tires, clear fenders and allow for mud buildup so they have the advantage for large tired and/or fender equipped touring bikes and for cross-bikes used in muddy conditions.

FarHorizon

If stopping power is your goal, go V-brakes or discs. Otherwise, I agree with the previous posters that double-pivot calipers are the equal of cantilever brakes.

DannoXYZ 

Pad size actually do not affect braking-power. Just durability. Force on the pads from the calipers is the same regardless of pad-size, and the resultant friction F=mu is the same. Just that having that friction spread out over a larger pad will have it not heat up as much and last longer.

Dual-pivots and cantilevers both work pretty well and can generate decent braking-power with less lever-force than single-pivot calipers. However, all three can generate more than enough braking-force to launch you over the bars. And in extreme cases with sufficient skill and insanity, even lock up the front-tyre. The ultimate braking-force comes from the tyre and how much friction it can generate on the ground to decelerate the bike. If you can lock up the front-tyre, you've got enough braking power...heh, heh...

genericbikedude

thanks all--its what I suspected. I'll see if I can get my hands on some NOS Mafac racers of a 27" frame, or some competicions for a 700c frame. I like slightly more mech advantage, as I like to start and stop fast on a freewheeling bike.

dafydd

there isn't really any correlation between wheel size and brake reach with the racers and competitions--there are plenty of older 700c bikes with racers. measure your brake reach and rely on that. i haven't used the compititions i have, but i find the racers a hassle to set up, flexy, and prone to squealing. in my opinion you'll get better results with dia-compe or weinmann centerpulls and make your own straddle cable if you want to play with mechanical advantage.

dafydd

also, depending on your brake reach and desired tire width and presence/absence of fenders, you could buy a very respectable set of dual pivots for the price of a set of nos competitions. maybe even two pair.

late

Do you want fenders?

Rev.Chuck

Depends on the setup, that is: the pad the angles of the the pad, the point of cross over. There is not a set of double pivot side pulls, on the face of the planet, that will match the cantis on my old mod trials bike. One finger lock up, and decent control.
I would base it on clearance and the frames you have available. For normal riding either would work.

Bekologist

this is not scientific, but an observation nonetheless: I live on a hill steep enough it has steps in the sidewalk, and flail down this thing on all my bikes all the time. I've got extralong throw Diacompe calipers on a 45 pound schwinn and they can lock 'em up just like the Shimano Br-550 cantis I've got on both my touring and mountain bikes right now. Maybe the calipers need a little more hand strength to brake hard with them, but that's hard to gauge. They seem to work a lot better than any brakes I had on bikes back in the seventies, and I don't know why- except maybe the extralong lever arm of the caliper itself adds mechanical advantage.

grolby

I haven't used too many bikes with sidepull calipers - most of the bikes I've ridden with calipers at all have been old ten-speeds with centerpulls. On my brother's Univega with single-pivot Dia-Compe G calipers, I have noticed one major advantage over cantilevers (the stopping power appears to be less compared to the cantis on my bicycle): with caliper brakes, the metal caliper arms mean that slack or bends in the cable is not a problem. With my cantilever brakes, both with a link wire and straddle cable, far too much lever travel goes into straightening out the brake cable, not applying braking force. What this means for caliper brakes is less lever travel to get maximum braking force, better modulation and less wasted force.

The combination of those properties and the large mechanical advantage of cantilever brakes is why I prefer V-brakes, which are unfortunately not an option on any of the bicycles I own right now. For all practical conditions, though, modern calipers are every bit as good as modern cantilevers of traditional design, with their chief disadvantages being lack of room for fenders. Older calipers have lots of room for fenders, but generally have less braking power (although it is perfectly adequate for most purposes). Cantis, on the other hand, may have to deal with cable slack and mechanical advantage that changes as the the brake arms move closer to the rim. Neither system is perfect, but neither one is inadequate compared to the other, though I would generally recommend cantilevers over calipers for heavier bikes (like a touring bike).

grolby

This is because of a whole constellation of reasons, including better brake levers, better cables and housing with less friction, and brake designs with better mechanical advantage. This is one of those areas where the newer stuff (from the last 15 years or so) just tends to work better, in general.

dafydd

i kind of don't see why a decent set of cantilevers with good springs and a proper-length straddle wouldn't get similar results. as far as modulation goes, i had to take a rear dual pivot brake off a bike as there was NO modulation--it was all on or off. while v-brakes are in general a vast improvement over older cantilever designs, they do have the weakness of requiring levers with a lot of pull and mininal clearance between rim and brake pad. most brakes have their place, and even when mediocre brakes are your only option, they can usually be improved by good cable and housing, prudent routing, and good pads (koolstops!).

grolby

Well, that's certainly true, dafydd, and I meant to say as much. I don't see the issues with cantilevers as problems so much as minor annoyances to people with OCD about their bikes - people like me! And while I do love me those v-brakes, if your wheel wanders out of true, you're going to be dragging your pads on the rim. Of course, your wheel shouldn't be going out of true! I stand by v-brakes as the last word in stopping power for rim brakes.

It's worth reiterating what you said about cable routing, too. Good cables and housing and careful routing are likely to do more for your braking system than any upgrade money can buy (although Kool Stop pads are also a worthwhile investment).

Sluggo

In general, the farther from the rim, the less leverage applied by a caliper brake. The big advantages of cantilevers is that they apply the same braking power with any amount of clearance, allowing their use on fat tires with mud clearance, without comprising braking power.

For normal road bike clearances, even with room for fenders, caliper brakes work fine. They are easier to adjust and the angle of attack on the rim changes less with brake wear. I like center pulls for moderate reaches (32 + mm tires with fender clearance) because they have somewhat more leverage than a sidepull at the same clearance. But I have bikes with cantilevers and sidepulls that work just fine.

Don Cook

"Pad size actually do not affect braking-power. Just durability. Force on the pads from the calipers is the same regardless of pad-size, and the resultant friction F=mu is the same."

The friction for any given mm2, or any other measured surface area, is the same given that the force and the contact materials are the same, as you stated. However, total friction and thus breaking force increases as the total swept area of the braking surfaces increase. That's why you don't have a bike with brake pads the size of pin heads. Larger diameter brakes (other factors being equal) provide greater stopping forces than do smaller diameter brakes. Just look to automotive examples.

San Rensho 

Why do you want so much brake, they just slow you down and then you have to pedal harder to get back up to speed? Seriously, I think either one is overkill. With either a caliper or canti brake I can get my back wheel in the air in a hard stop where I am trying as hard as possible to keep the back down. I would worry more about progressive brake feel and I prefer the caliper for this.

DannoXYZ 

Show me where you derive higher "total friction" in relation to "total swept area"? If we have 20-lb of force from each caliper arm, how does that affect how much friction we have on the pad? If we upgrade to a pad twice as large, do we suddenly have twice the friction? Why bother with brake-caliper designs and upgrades at all then? Let's just slap bigger pads the size of bananas on and that's all we need.

The reason we don't have pin-head pads is that in order to generate that same amount of friction on a smaller surface area, you'd end up wearing away the pads in a single stop. Again, review f=mu and you can even calculate deceleration-rates and stopping-distances if you want. The limiting factor in the end is the maximum amount of friction the tyres can generate against the ground.

Also, race-car brake-upgrades is to shed heat. Dissipating 3000lbs of kinetic energy into heat is what slows down a car. Bigger, heavier brake-rotors heat up less for the same amount of heat generated (they're heatsinks). Their larger surface area also sheds heat faster. This allows you to not overheat the brakes on the track and can do repeated stops over and over again. Big brakes will last 100-laps while small ones will overheat and boil the fluid, resulting in fade within 10. But any single stop (starting at the same brake-temperatures), with bigger brakes will not be of shorter distance or faster than smaller brakes. It's durability we're after. The only way to significantly affect the braking-distance on a car is to get stickier tyres, lower-weight and/or increase downforce.

The diameter of bike-brakes don't change, so we can't compare with auto brakes. What larger diameter rotors do is allow for more mechanical leverage against the tire. Imagine two levers, the pivot is the hub. One lever is with the contact patch on the ground to the hub. The other lever is from the middle of the brake-pad to the hub. Since the diameter of the rotor is smaller than the tyre, the resisting torque generated by the pads is smaller by the time it gets out to the tyre. What the larger diameter lets you do is get more resisting torque on the tyre with the same pedal-effort or pad-force. In the end, braking distances will still be determined by total friction of the tyres on the ground. Just that with larger rotors, you can lock them up with less pedal-force than with smaller rotors. However, braking-distances will still be the same. It's like grabbing your brake-levers at the tip or in the middle. It will require less finger force at the ends of the lever for the same braking-force as squeezing in the middle... however, your braking-distances will still be the same.

With bikes, the diameter of the braking surface is always pretty close to the diameter of the tyre. If you want to compare disc brakes vs. calipers, you'll find that you have to apply a LOT more force at the disc in order to generate the same braking-power as pads on the rim.

BTW - I did a test of maximum-braking that San Rensho mentioned. Came up to a stoplight in the bike-path next to the cars waiting. Picked it up to 20mph to have a standard control speed, slammed on the brakes as I passed the rear-bumper of the 2nd to last car. Let go of the rear-brake when my seat came up and hit my belly and I was pretty much fully stopped by the door of the 1st car... Eased up on the brakes to reach the crosswalk in front and grabbed teh front-brake again and hopped/pulled up on the pedals. Held a nice stoppie for about 2-seconds...heh, heh...

Rev.Chuck

"The only way to significantly affect the braking-distance on a car is to get stickier tyres."
This is mostly true if you only need to stop once.
My autocross car with 032R's will smoke my big sedan in the first couple of stops. My big sedan with Proxes and big slotted rotors front and rear will out brake the Scirocco after a bunch of long, hard stops. The 9.7s on the little car just can't dissipate heat like the 12's on the bigger car. Even tho the smaller car weighs more than a 1000 pounds less, tho the weight difference also comes into play for braking and handling.

It is hard to compare hydraulic multipiston brake calipers to a rim brake pad operated by a cable.

DannoXYZ 

Exactly! The friction of the tyres determine the ultimate shortest braking-distance possible. The size of the rotors determine how many times you can repeat that short braking-distance. Best of both worlds is to have both sticky tyres and BIG brakes!

heh, heh.. just put a set of these 330mm bad boys on...


(customer car)

Rev.Chuck

Pad materials also come into play, for a car anyway. Both of my cars will scare you first stop on a cold day, full metallic pads, and nothing until they warm up a little.
I imagine that there are some compounding differences for rim pads but the only noticeable ones I have seen are ceramic v/s conventional. I also have some special compound pads(citric) on one of my trials bikes that have an amazing grip, you can't ride around with them but if you need to balance, back wheel, on the lip of a drop they are the stuff.

DannoXYZ 

I have noticed that different pads require different amounts of lever-force for the same braking-force. Some of the stock black pads on the Shimano brakes are horrible. Don't the various KoolStop pads of different colors indicate different pad compounds? Or are they just color variations for the OCP fashionable folks who want to make sure their pads match their outfits that day?

Rev.Chuck

They claim(or used to) that the colors are different friction compounds, but I have tried them and not really noticed any difference.

Michel Gagnon

There are three types that are actually different. According to their chart and some personal experience, I would say:

– Black : smooth and efficient in dry weather, but tends to be uneven in cold rain or ice: doesn't stop until the rim is dry, but then grabs suddenly.

– Salmon : in dry weather might need a little more strength than black; but almost as efficient in rain and still quite decent in icy weather. If I have ridden 5-10 km in the snow without applying the brakes, I still need to apply the brakes for 2-3 wheel rotations before they are really effective.
Also, they have a reputation of being good for the rims and long lasting, even when riding in foul weather.
BTW, Salmon (good) is not the same as red (not so good)

– Green : supposed to be a special compound for ceramic rims.

– Other colours : marketing only?

– Yellow tip : would it be a solution for a problem I don't have? Maybe for too flexible brake arms?

- Dual compound : that's in effect a pad with a black front third and a salmon rear 2/3s. I only had one experience with full Salmon front brake pads (as opposed to dual), and I think the dual are smoother if I just want to feather the brakes.

– Kool Stop Eagle II vs Thinline or BMX: Similar in dry weather or even in light rain, but I find the Thinline or BMX have a profile that does a much better job in evacuating snow and large amounts of water. I suspect they would also be better in mud.

– Kool Stop Thinline vs BMX vs refills (to use with holders). Take your pick. Here we pay the same price for either, so it makes sense to buy the BMX pads unless there is too little clearance for them. BMX pads last 2-3 times longer than Thinline pads.


In terms of durability, I use a lot my touring bike in the city and I used it a lot while towing a trailercycle and a child trailer. Avid and Shimano pads didn't last a full month, but Thinline pads lasted 1 year and BMX pads have lasted 2.5 years.

MichaelW

I switched from a 1970s caliper to a modern Shimano dual pivot caliper and noticed a huge improvement in stopping power and modulation.
Modern calipers (with matching brake levers) offer better modulation then calipers. They also require less strength to operate, esp down long descents.
The only advantage of cantis is clearance if you need wider than 32mm tyres + fenders.