Why are there no tests of disc vs rim brakes stopping distance on alloy rims in the wet? We know carbon rims perform poorly with rim brakes but alloys can work well given good pads and decent road bike rim brakes. Worthy subject for study I think.
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Some of these types of tests were done like 10 years ago. They are hard to do, and generally the results were unsatisfying for most. People still found enough points to pick out their favorite brake type and declare it the winner. But the reason you don’t see those today, is that there aren’t any rim brake bikes to compare to.
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I like rim brakes. My favorite bike is a Supersix Evo HM with rim brakes and HED jet wheels with machined brake tracks. That said, I’m choosing disc brakes 10 times out of 10 in the wet.
Not only are the disc brakes way more predictable feeling in the wet, but they don’t eat your rims. There are two places I think disc brakes are absolutely the best choice and that is off road and in the wet.
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Agree. Where I am, wet includes grit and the lovely sound of your alloy rims being ground into black sludge.
I like the simplicity of rim brakes. I’m happy with my rim-brake road bike on relatively clean dry pavement, but everywhere else I think discs are a better option.
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Yeah the rim brake boat sailed. For many riders in flat dry not too hot conditions disc brakes were an answer to a question nobody asked. But for other conditions it’s no contest. But it doesn’t matter really, the industry has geared up to disc and it’s lights out for rim brakes. Next will be the elimination of mechanical gear activation.
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If you get rid of mechanical drive trains, you’ll kill entry level bikes, utility bikes, etc and make getting into cycling prohibitively expensive. Rim brakes will also continue to exist for many of the same reasons.
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Love my rim brake bike in pretty much any condistions, save one: wet. As a long time rider in the Pac NW, I rode rim brakes for years in the rain. Calipers, then canti’s. No matter the pad material, there was always that small moment of waiting on the brakes to grab. That was all great until one day when…well, you get the drift.
Since switching to a disc cross bike for winter, no more worries about control. I ride that bike as much, maybe more than my rim brake bike. And the maintainance is pretty straight forward, in some ways easier. Sure, you can line up a test, but the rim brake ship has sailed, except for a few Luddites (myself included).
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Worth mentioning too that absolute braking power is not the ultimate metric that matters. Modulation with disc is far superior too which increases the safety margin in favour of disc.
The option to fit wider tyres at lower pressures also increases tyre contact patch on disc brakes so risk of losing directional control further improves safety.
Rim are good in ideal conditions but disc win across all conditions despite added complexity of set up, weight and possibly aero
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It’s an interesting question. The part of my brain that understands physics has withered to the point that even positing a good model is beyond my powers now. Based on personal experience riding similar-ish bikes in similar-ish conditions on similar-ish terrain over many miles, it’s probably a few feet at most in real-world conditions. Anything more than that, and you’re probably more worried about locking up a tire and going down than about the relative difference in stopping distance actually achievable by an average human being. And that’s not nothing! “A few feet” is enough to be the difference between “mostly before the intersection” and “the middle of the intersection” (or worse).
I can remember descending in Austria on an MTB with v-brakes in the rain and my hands cramping from the amount of pressure and time I had to apply the brakes to achieve adequate braking force. In dry conditions I had no such issues. The rim brake really is just a giant disc brake after all, albeit susceptible to rim trueness and the issues of braking power vs pad compound. I really didn’t rush to disc brakes to be honest. But, running wider tires on my road bike for gravel and asphalt finally pushed me over. My old road racing buddies still lament the imminent demise of rim brakes on bikes of any financial consequence and I actually understand it.
But the industry dun care what I think.. it’s like wishing for an aluminum tennis racquet. Good luck.
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This “comparison” really needs to die…it simply isn’t accurate. There are multiple reasons why they are significantly different.
As for the requested comparison study, there is zero reason to do it. The horse has long left the barn. Rim brakes aren’t coming back….and that is largely a good thing.
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It would be still nice to see some comparative stopping distance data (disc vs rim on alloy rims in the wet) on tarmac which I can’t find. Is it too cynical to suggest the manufacturers didn’t want it published by sponsored websites?
Why wouldn’t manufacturers want it published? Is it your contention that rim brakes in the wet are better than disc brakes in the wet?
There is no “disc brake conspiracy”.
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It’s entirely accurate. Having said that, they are certainly two completely different implementations! Fyi I’m not conspiracy guy, I’m quite happy with disc brakes as are most people I suspect.
Rim brakes are going to be around for a long time. They may not be the dominant brake option, but they’ll still more widely used than you think. Outside the well isolated EC bubble, there are a lot of bikes with rim brakes and a lot of folks who might potentially give cycling a try. It will be easier for those folks to do that if there are bikes that are more affordable. Having rim brake options is one of several factors that will help make entry level bikes cheaper.
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I think the issue with a good comparative stopping distance test is all of the variables that have to be constrained or quantified to make the test a good test.
I’m pretty sure the OP was not referring to entry price point bikes in his post.
But even then, they are increasingly vanishing from lower price points as mechanical disc brakes come down in price points.
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I wish more people here would try to answer OP’s question rather than offering their own tired perspectives on rim brakes vs disc that we’ve all heard before.
Why are there no tests of disc vs rim brakes stopping distance on alloy rims in the wet?
Because there are too many variables.
Wet with what?
Clean water ? Not a real world situation.
Diluted road sludge? Whose road? How much sludge? What’s in the sludge?
It’s close to impossible to answer the question in a robust and repeatable way.
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Isn’t the answer that any two same material rims will be much of a muchness, and the difference between alloy and carbon rims will likely reveal the obvious?
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