aclinjury

Do bigger brakes give more stopping power? No. Stopping power is determined by the coefficient of friction of the pads (which doesn't take pad area into consideration).

Do bigger brakes give any performance advantage over smaller brakes? Yes, eg, better heat dissipation. (Heat the number 1 enemy of any brake system)
https://www.cquence.net/blog/big-bra...-do-they-work/

Do bigger brakes give more "modulation"? Not necessarily.
"Modulation" depends on 2 things:
1. the mechanical property of the brake system
2. the human hand, which is a trained behavior
You can give the exact brake system to 2 different riders, and each will invariably describe that the brake system feels different to them. This is because of the human factor; some people like it soft and gentle, some like it hard and abrupt, when it comes to braking. It's some they learn and have mentally adapt their fingers to do. It's a muscle memory thing. But in general, the bigger the disc rotor, the better the modulation will feel to the rider. But of course bigger rotors also have their own issues, like warping, and contamination.

cyccommute 

There are two things you aren’t taking into account. First, as the lever moves toward the bar, the angle of the leverage lessens. If you start braking when the lever is at a low angle, the leverage that can be developed is less.

Secondly, a long lever pull means that more cable has to move and the cable stretches more. It’s a smaller effect but it’s still significant enough to make the brakes feel mushy.

And, again, these effects can easily be demonstrated with a hub mounted mechanical disc. Move the pads away from the rotor and the braking ability suffers significantly. And it does so with far less distance from the rotor.

Koyote

Thank you for actually addressing my point/explanation. This is what I was expecting when I wrote that "I'm willing to be corrected if I'm wrong."

Your points make sense, but please tell me what you think of the following - I am genuinely curious:
1) I would think that the 'leverage' effect is pretty slight...In fact, maybe it's just my hands, but I feel like I can generate more force when the lever is drawn a bit closer to the bar.
2) I would also suspect that having even an additional cm or two of cable, which is a small % of the total cable run for even a front brake, would also be a relatively minor effect.

The reason I wonder about these issues: I generally feel like I have better control of my rim brakes, and just as much total braking power, when there is a room for more 'lever pull' before they fully lock down on the rims...In other words, I set them up to draw a bit closer to the bar at full force.
Thanks again.

AdkMtnMonster

Can we *PLEASE* go back to drum brakes and be done with these silly modern day miracles? I’m tired of cool new stuff and having choices.

cyccommute 

That’s the most common one, yes. However in nonstraight ahead situations, locking the front wheel won’t result in a good outcome. A nonspinning wheel is unstable. That’s why a skidding rear wheel tends to move from side to side during a skid. If you could skid the front wheel, it would do the same and the rider is going to have difficultly staying upright.

It is a strange difference indeed. By “do[ing] manuals”, I assume you mean nose wheelies. That’s not a measure of modulation in my opinion. It may be a measure of power but I can lift the wheel of just about any bike I own with just about any brake own.


I don’t know what brakes you have used but I’ve used a lot of different linear brakes. I work on a lot of linear brakes on other people’s bikes. I’ve never experienced one that is as you describe. Nor have I ever had anyone at my bike co-op complain about linear brakes being to grabby.

I have experienced hydraulic brakes that are digital...the opposite of good modulation...with exactly the on/off quality you describe.

I didn’t say it was a good idea. I only said from a braking stand point, you could use a pad that would be more effective than rubber.

As to making the rims, there are all kinds of complex shapes extruded from steel. It would be trivial to make a steel rim in exactly the same shapes are aluminum rims. You mistaken about the properties of steel. Steel isn’t a flexible material. It’s 3 times stiffer than aluminum. Steel rims have been made in the past and a steel rim is the opposite of flexible. A steel rim doesn’t need the same shapes as aluminum because it is inherently stiffer. It wouldn’t need to be double walled to resist bending. A steel rim at the same weight at an aluminum one would be stiffer and stronger.

I’m not advocating steel rims, however. This is just a thought experiment.

I’ve been building wheels for 30 years. I’ve never heard a spoke and nipple being referred to as “sealed”. You have the process reversed. A thread preparation is applied to the spoke before it is threaded into the nipple. The spoke/nipple junction is then lubricated with an oil of some kind. The thread prep is used to keep the nipple from vibrating loose by putting material in the threads but it doesn’t “lock” the threads. The spoke/nipple junction is never “sealed”. In fact, during truing, it’s advantageous to add some oil to the spoke/nipple junction to make it easier to move the nipple on the spoke.

As to truing a wheel, all that is usually needed is a simple turn of a spoke or two to bring the rim into alignment. There are 22 threads per cm on a spoke. It’s very precise because you have a gauge telling you how much to bend the rim. I teach people how to do it all the time and it’s easy for them to grasp the fundamentals and apply them.

Contrast that with a rotor alignment. The only way to true a rotor is to bend it. It’s only a guess as to how much the rotor needs to be bent. There’s no real way to tell if the rotor has been bent enough or too far. There no small adjustment ability like there is on a spoke. I’d much rather make adjustments to something by using threads than by simple bending it.


You are saying to opposite things. Do you need a significant gap or a tiny gap? You’ve said both. People set up rim brakes with a significant gap but there is nothing that says there has to be a significant gap. It doesn’t improve the performance of the brake. Even if there is a smaller gap, there is nothing that dictates constant adjustment.

You keep saying things that make no sense. There is no lever that compensates for caliper travel that I know of. Brake levers are simple mechanisms. The lever is a body that has a pivot point on it and a lever that rotates around the pivot. What would compensate in that system from caliper travel.

Disc calipers and rim calipers work on exactly the same principle and very, very similar mechanisms. Something moves the pads into the rotating metal disc. Whether that is an arm or a piston doesn’t really matter all that much.

cyccommute 

Your argument falls apart when you consider the types of levers used. You can’t use a long pull lever on a short pull brake because of the cable pull ratios. However, we don’t have different levers for hub mounted disc brakes...at least for mechanicals. Mountain bike disc brakes use the same levers as linear brakes and road bike discs use the same levers as short pull side pull calipers and cantilevers. No adjustment needs to be made for any differences in leverage...only cable pull.

Kapusta

Actually, I was talking about the opposite: I was pointing out why you don't use a short pull lever (canti lever) on a long pull caliper (v-brakes). And the reason for that is different.

The reason for not using a long pull lever on short pull brakes (what you mention) is there is not enough mech advantage, and you have to pull much harder to generate the same force on the pads.

The reason for not using short pull levers on long pull brakes (what I was talking about) is that you don't move the pads far enough. You either need a long lever through, or you need to set up the pads too close to the rim and will be dealing with rubbing often.

"Long pull" and "short pull" are just different ways of describing the mech advantage of the brake lever: long pull = low leverage/mech advantage, short pull = high leverage/mech advantage.

So, back to my point: I am pointing out that there is a practical limit in how much leverage/mechanical advantage you can design into rim brakes. And that is the amount of distance the pad needs to travel. To demonstrate that point, I used the example of what happens when you try to increase the mechanical advantage of rim brakes (using a short pull lever on long pull brakes). As you probably well know, it does not work well.

True, but not relevant to the point I was making.

If you want to continue this., please go back to my post #26 and explain what exactly I am wrong about. I am basically stating three things:

Point 1 states that the leverage between the lever and pads is different for disc vs rim.
Point 2 explain why is is needed.
Point 3 explains why it is possible

Which one do you disagree with.... or is there some other conclusion you think I am implying?

79pmooney

Cantis - my Mooney went down Alba Road above Santa Cruz its first winter in a driving Pacific Storm. Sheets of water running across the road. (Alba Road is a paved 1/2 Mt Washington in NH. Same grade. Similar corners. No ability to build speed and use wind resistance for braking because you won't make the next corner, especially in the wet.) Mooney came with the old Mafacs (well 1979 new, but unchanged since the '50s) and standard Mafac pads. What was notable about the braking was that I had all the power I could use with that wet road using just one finger per brake the first half, then two for the rest as the cold and wet took its toll. Never remotely scary. Thought at the bottom - "good brakes! Keepers!

10 years later I swapped out those cantilevers for the Shimanos that came on a used Miyata 610. Nicer to work on, Same geometry, same stopping power. They are still on the Mooney and I have no desire to change them. (I am getting older and have run into tired hands, even needing a stop for them on miles of gravel descent, but the stop was needed anyway to refocus or I was going to crash again. Brakes had zero to do with the first - hard - crash. Picking a poor line and ending up in a two foot deep rut can lead to issues.)

One thing I have done with most of my brakes (all but the old centerpulls and sidepulls) is to go with V-brake levers - specifically to reduce the power so when I do a mountain descent and come up fast on a turn I see I won't make, I can shut down my speed fast and not lockup or have anything exciting happen. First time was sorta by accident. I was setting up my new, custom mountain road fix gear and picked up some used levers with huge hoods that my hands would love. Quickly noticed the very fast but low powered braking and also that my hands were truly happy uphill so I left them on. Rode the setup to McKenzie Pass, then back down to Sisters, OR. Came to an unexpected sharp turn at real speed and knew right away my pedals weren't making it! Fully adrenalized brake grab! And nothing happened except I made the corner at a leisurely 20 mph. Sold!

The centerpull bikes are on the bikes that get regular rain rides. Mafacs and road levers have a lot of stopping power to clean wet rims, so they stay. (Those bikes also see winter, city and low light use and might get meddled with when locked up. Keeping something as important as braking as simply, reliable and easy to fix as old school brakes makes for piece of mind. (And there's little a 5 year old can do to them, no fun hoses to pull. Not much I have to remember - like "don't squeeze that brake - no wheel!")

Yes, the next new (non-custom) bike I buy will be disc. But that may not happen in this lifetime. We'll see.

Ben

79pmooney

Bah! My internet provider, CenturyLink, at its best.

elcruxio

Like I mentioned in my earlier post, I believe most better levers compensate for that, ie. they compensate for the lever movement so that no matter the lever position you get the same leverage.

That doesn't sound entirely correct. The cable travel difference in miniscule when comparing to the complete length of cable in use. Also the contributing factor for cable stretch is not the travel distance but rather the force the cable is pulled with. Other compounding factors are housing length and thus also housing compression.

If anything, road type brake systems should cause a mushy brake feel as they pull less cable but with greater force than mountain brake systems. But that doesn't seem to happen as road brakes are, I find just as crisp as mountain systems.

PAD, not PADS. The unmoving pad must always stay in place. If you move that then of course braking performance suffers as the rotor has to needlessly flex and also loses pad contact area as a result. But moving the moving pad out doesn't cause issues nor does it degrade braking performance as long as the lever doesn't pull into the bar.

Very true. Hence I prefer braking systems which allow me to toe the line of front tire skidding. I've only fallen once due to a front tire skid and that was due to carelessness on a wet mossy surface.

Manual in my understanding is as you say a nose wheelie which is then sustained for a period. It's the sustaining the manual which requires precise brake modulation.

All I know is that I did not like them when I used them in my LHT. Also Shimano used to make these elastomer brake modulators which would effectively work as extra compressible break housing. I've only ever seen those used with full sized vee brakes. Also there's this weird 'wisdom' older folks have according to which one should never brake with the front brake. This 'wisdom' to my knowledge comes from the advent of vee brakes when people would frequently endo with front braking. I have spent some considerable effort in teaching my wife away from that weird belief and nowadays her front pads have finally started wearing faster than her rear pads.

I am genuinely interested in the models you've tried which were digital. Though I'll admit I do kinda see a pattern here. You don't see a problem with cantilevers which to me require some considerable squeezing to get any power out of. If you move from that to hydraulic brakes I can see how they might seem digital. But the hydro brakes I use are not even one finger brakes, they're fingertip brakes as in I get all the power I could ever need with very little effort and it's the most accurate braking I can imagine.


Well, no. Aluminum is three times lighter but what you fail to account for is stiffness via thickness. An aluminum part has to only be 44 % thicker than the steel part to be as stiff. Hence aluminum frames tend to be stiffer than steel frames but that's a different discussion.


It's my term that I use. The way I build wheels is set and forget. I use boiled linseed oil and while its still liquid and in lubricating form I build the wheel, stress relieve it, retrue it and usually never need to touch it again. The sealing means that when the linseed oul hardens it lightly locks the nipple threads.

The way I see it, just tensioning the spokes so that the rim is pulled is bodging it. To propely true a wheel is to tune its tension as well. This in turn makes truing a bit of a hassle as it typically requires the adjustment of multiple spokes on both sides of the wheel. This is of course with wheels which haven't been built by me.

As to rotor truing it's literally a few quick adjustments and off you go. Of course a rotor only needs to be true enough and that level of trueness is quite easy to achieve.

I'll assume you just read my post too quickly and missed the point I was making. Different rim brake systems require different gaps. Dual pull calipers can be fully open without pretensioning and adding tension to the brake doesn't in my experience add much to the performance. Fully open the gap is quite significant. Cantilevers always require a bit of pretensioning of the brake cable and also require the pads to be close to the rim. You get the point. Different brakes, different requirements.

Did I write that the lever compensates for caliper travel? Sorry, must have typoed . What I meant was what I wrote above, ie. the lever compensates for the lever. In effect it means that no matter what the lever position, it'll always pull the same amount of cable This is achieved with the pivoting cable holder and some smart lever design. So in effect it does not matter at which position of lever travel the brake bites as the cable pull is linear with the lever movement range.

theDirtyLemon

I have read this entire thread and am now exhausted and mildly nauseaus.

Everybody shut up and go home.

Kapusta

I think the problem is that so many of us ARE home. Stuck here and going a little crazy.

theDirtyLemon

The real problem is I can't spell 'nauseous'.

Koyote

Get out and ride! It's at least safe, in most areas. I've been doing about 200-250 miles per week since the pandemic started.

matt92037

i was hoping for some thoughts on my specific disc brake issues from folks who have ridden both. Before this turned into what it did.

Troul 

must have permissible weather to enable such isolated activity.

Just put away the snow shovels & preparing for the windy rainy 60s.

elcruxio

Looking outside it's currently 4 degrees celsius (39 degrees fahrenheit) and raining. I think I'll pass on the cycling today. On the weekend we had 10m/s winds which also kinda takes the fun out of cycling.

Bill in VA

I have seen a Swiss Army bicycle with hydraulic calipers on the rims and no disc. Than again, the bike with racks and storage compartments was over 60 pounds, and the calipers were fairly large and complex..

Oneder

The contact point on rim brakes is also small

shelbyfv

I was going to prod you about using "nauseous" instead of the correct "nauseated." Well, joke is on me because sometime in the nearly 50 years since I was in school the distinction has been lost! https://www.grammarly.com/blog/nauseated-vs-nauseous/