Real world difference in stopping? Single vs dual
#91
04-03-2016 | 09:02 PM
Cruiser
Joined: Feb 2016
Posts: 149
Likes: 27
From: Quiet end of Silicon Valley
What part of keeping a stock brake system, if it happens to outperform many sportbike brakes in street riding, involves "skimping"? Or are some people still clinging to fantasies that their street-driven Harleys are race bikes, benefiting from brakes that will pull them down repeatedly from 160 mph? LOL
Hello, brake setups that work well for racing don't necessarily work well at all on the street. There can be some tradeoffs. For example, brake pads designed to work well at high temperatures can feel pretty slick, and give poor stopping power before they are brought up to design temperature. But if you don't mind driving around on the street, dragging the brakes all the time to keep them heated, maybe they would work OK.
It's a little like assuming that since most race bikes are making their best power over 10 thousand rpm, that's where you'll be getting the best power out of your Harley engine.
If you don't "skimp" on tires, are you running racing compound slicks on the street at all times when the roads are dry, for maximum traction and braking? And switching back and forth between those, and grooved "rain" racing tires, depending on the weather? If not, doesn't that amount to "skimping", versus the safest and and best performing setup?
Or how many of you run Y or Z rated tires, so you'll have the right tire in place whenever you drive your Harley 186 miles per hour?
Hello, brake setups that work well for racing don't necessarily work well at all on the street. There can be some tradeoffs. For example, brake pads designed to work well at high temperatures can feel pretty slick, and give poor stopping power before they are brought up to design temperature. But if you don't mind driving around on the street, dragging the brakes all the time to keep them heated, maybe they would work OK.
It's a little like assuming that since most race bikes are making their best power over 10 thousand rpm, that's where you'll be getting the best power out of your Harley engine.
If you don't "skimp" on tires, are you running racing compound slicks on the street at all times when the roads are dry, for maximum traction and braking? And switching back and forth between those, and grooved "rain" racing tires, depending on the weather? If not, doesn't that amount to "skimping", versus the safest and and best performing setup?
Or how many of you run Y or Z rated tires, so you'll have the right tire in place whenever you drive your Harley 186 miles per hour?
Why not have the best brakes possible? Why not have the best suspension possible? With the amount some are putting into motor work, which does nothing more than make a slightly faster louder slow bike, you could replace the entire braking system and suspension and have something that you'll really notice and make it safer at the same time.
Why fight over making something like this better?
Because there are no bragging rights in your circle of friends? Too tough to be a sissy who wants brakes that work?
Chonk
#92
04-04-2016 | 03:22 AM
Road Captain
Joined: Oct 2015
Posts: 706
Likes: 28
From: Alaska
I have to say that going from the Single Disc to the Dual Disc ABS on the Dyna Low Rider S was strange for the first 100 miles while it wore in. I had to slam on them yesterday and ILL NEVER GO BACK to the single!! They really do make a difference and once your used to the feel you will be glad to have them.
Like the OP asked for.
#93
04-04-2016 | 04:23 AM
Outstanding HDF Member
Joined: Aug 2012
Posts: 3,217
Likes: 88
From: Detroit
Why not have the best brakes possible? Why not have the best suspension possible? With the amount some are putting into motor work, which does nothing more than make a slightly faster louder slow bike, you could replace the entire braking system and suspension and have something that you'll really notice and make it safer at the same time.
Why fight over making something like this better?
Chonk
Why fight over making something like this better?
Chonk
Brakes work by slowing the rotation speed of the wheel. If they will do this effectively enough to exceed the traction coefficient available between the tire and the road surface under all riding conditions, then the brakes are already doing about all that it's possible for them to do. Tire traction becomes the limiting factor. So in this case, the first practical brake upgrade would be using tires with better traction. On some models, this first step might involve putting on a wider rim to handle something wider than a "pizza cutter" tire. Or if one was really serious, it might involve installing a wheel sized to handle the more common sizes of soft-compound or high-traction sportbike or racing tires. Sure, tire longevity will go out the window, but if your true top priority is best braking, and not just pretending, that won't matter, right?
There is no value in having brakes with the heat dissipation capability to repeatedly haul you down from 160 mph, if the bike isn't even capable of going 160. As I mentioned earlier, I took my Dyna (single disk) out and did 5 heavy stops (60 to 10) in a row, front brake only, using no engine decel, at about the limit of tire traction, and there was no loss of the ability to exceed tire traction. Actually, the number of hard stops was 8, but I didn't count three of them, because they were practice stops to get a sense of where the traction limit was, and there was a short break before the next 5, while I checked the bike over.
So once again, the issue isn't whether or not one wants good braking. The issue is barking up the wrong tree in trying to achieve it.
#95
04-04-2016 | 05:55 AM
Seasoned HDF Member
Joined: Sep 2013
Posts: 6,171
Likes: 1,947
From: Great State of Canada
This:
Got answered here:
Beyond this there have been a spate of "for the sake of argument" interjections including, "quite remarkably" that someone was implying that single discs were actually better than doubles ?? I missed that one.
If brakes can be applied aggressively enough to cause ABS modulation to kick in, is that not as good as it gets ?
Could it be that felt ease of braking at the brake lever is the primary benefit of dual discs ?
Beyond product development and experiment, Is comparing a cruiser to a track machine operationally "at all" valid ?
As to "good enough" being an irresponsible argument and "only the best will do" being the the nobler point of view,, well, virtually everything imaginable arrives at its "good enough" status sooner or later. This is governed by what Economists call the Law of Diminishing Returns and explains why the, "more is always better" ideology eventually comes to an end. Incrementally, each unit of improvement costs exponentially more in terms of both money and excess, as illustrated here:
Diminishing Returns Illustrated
This explains why we aren't arguing; "3 discs are better than 2" or "4 discs are better than 3". Though such statements are probably true at each successive level, there remain few absolutes in life and sooner or later, as with cable TV
, you've got to "settle". At some point good enough really is good enough. Even the overburdened sacred cow of safety must eventually defer to this undeniable fact.
I agree, multiple consecutive emergency stops should not be necessary on the street, if one is a decent rider.
However, I was still curious about what the single front disk could take, so I just got back from doing a short informal test on my 06 Dyna, which has stock Harley brake pads.
Procedure:
At 60 mph, using only the front brake (no rear brake or engine decel.. clutch was disengaged), I braked to 10 mph at a rate fast enough to produce a little chirping to howling from the front tire as it went over small irregularities in the road. Immediately accelerated to 60 again as fast as I could, and repeated. Did this five times in a row with no perceptible loss in braking force, or fading. The brake was still capable of howling the front tire on braking, with no increase in lever effort that I could discern. So traction available from the front tire was still the limiting factor, not the single disk.
I had hoped to take it to the point of fading, but five hard pulldowns in a row was the best I had a chance to do before traffic was coming up behind me. (no, I'm not going to do this with a car close behind me
)
Still, not bad, don't you think? And it certainly did better than the guess in post #26, that things would go downhill after 3 stops.
Yeah, I was a little nervous. It's been a while since I practiced threshold braking (the last time was on a sportbike, and it was my first time doing it on the Dyna), but the Dyna seemed to do it just fine.
However, I was still curious about what the single front disk could take, so I just got back from doing a short informal test on my 06 Dyna, which has stock Harley brake pads.
Procedure:
At 60 mph, using only the front brake (no rear brake or engine decel.. clutch was disengaged), I braked to 10 mph at a rate fast enough to produce a little chirping to howling from the front tire as it went over small irregularities in the road. Immediately accelerated to 60 again as fast as I could, and repeated. Did this five times in a row with no perceptible loss in braking force, or fading. The brake was still capable of howling the front tire on braking, with no increase in lever effort that I could discern. So traction available from the front tire was still the limiting factor, not the single disk.
I had hoped to take it to the point of fading, but five hard pulldowns in a row was the best I had a chance to do before traffic was coming up behind me. (no, I'm not going to do this with a car close behind me
)Still, not bad, don't you think? And it certainly did better than the guess in post #26, that things would go downhill after 3 stops.
Yeah, I was a little nervous. It's been a while since I practiced threshold braking (the last time was on a sportbike, and it was my first time doing it on the Dyna), but the Dyna seemed to do it just fine.
If brakes can be applied aggressively enough to cause ABS modulation to kick in, is that not as good as it gets ?
Could it be that felt ease of braking at the brake lever is the primary benefit of dual discs ?
Beyond product development and experiment, Is comparing a cruiser to a track machine operationally "at all" valid ?
As to "good enough" being an irresponsible argument and "only the best will do" being the the nobler point of view,, well, virtually everything imaginable arrives at its "good enough" status sooner or later. This is governed by what Economists call the Law of Diminishing Returns and explains why the, "more is always better" ideology eventually comes to an end. Incrementally, each unit of improvement costs exponentially more in terms of both money and excess, as illustrated here:
Diminishing Returns Illustrated
Each Incremental improvement = “1”
Cost per “1” = increasing $
1 more
costs $
1 more
costs $$
1 more
costs $$$
1 more
costs $$$$
1 more
costs $$$$$
1 more
costs $$$$$$
This explains why we aren't arguing; "3 discs are better than 2" or "4 discs are better than 3". Though such statements are probably true at each successive level, there remain few absolutes in life and sooner or later, as with cable TV
, you've got to "settle". At some point good enough really is good enough. Even the overburdened sacred cow of safety must eventually defer to this undeniable fact.
Last edited by HKMark23; 04-04-2016 at 06:11 AM.
#96
04-04-2016 | 06:58 AM
Outstanding HDF Member
Joined: Aug 2012
Posts: 3,217
Likes: 88
From: Detroit
Excellent post, HKMark.
I would say so.
One possible and unusual exception would involve an extremely skilled rider braking on a paved surface with pre-known traction properties. In real life though, on the street, traction properties will be changing all the time, including with changes in road surface, temperature and moisture (even between sunny spots and shadow), and this will make it almost impossible to actually achieve threshold braking in an emergency situation. But ABS can do this quite reliably, even if the rider isn't very skilled, as long as the rider isn't too timid to activate the brakes hard enough to kick the ABS in.
One possible and unusual exception would involve an extremely skilled rider braking on a paved surface with pre-known traction properties. In real life though, on the street, traction properties will be changing all the time, including with changes in road surface, temperature and moisture (even between sunny spots and shadow), and this will make it almost impossible to actually achieve threshold braking in an emergency situation. But ABS can do this quite reliably, even if the rider isn't very skilled, as long as the rider isn't too timid to activate the brakes hard enough to kick the ABS in.
Last edited by Warp Factor; 04-04-2016 at 07:37 AM.
#97
04-04-2016 | 08:05 AM
Seasoned HDF Member
Joined: Sep 2013
Posts: 6,171
Likes: 1,947
From: Great State of Canada
Excellent post, HKMark.
I would say so.
One possible and unusual exception would involve an extremely skilled rider braking on a paved surface with pre-known traction properties. In real life though, on the street, traction properties will be changing all the time, including with changes in road surface, temperature and moisture (even between sunny spots and shadow), and this will make it almost impossible to actually achieve threshold braking in an emergency situation. But ABS can do this quite reliably, even if the rider isn't very skilled.
The other exception is when riding in dirt, or on gravel roads. ABS can hurt stopping distances a lot there, but dirt riding isn't really what we're talking about here.
I would say so.
One possible and unusual exception would involve an extremely skilled rider braking on a paved surface with pre-known traction properties. In real life though, on the street, traction properties will be changing all the time, including with changes in road surface, temperature and moisture (even between sunny spots and shadow), and this will make it almost impossible to actually achieve threshold braking in an emergency situation. But ABS can do this quite reliably, even if the rider isn't very skilled.
The other exception is when riding in dirt, or on gravel roads. ABS can hurt stopping distances a lot there, but dirt riding isn't really what we're talking about here.
Where avoiding accidents is concerned, it seems to me that understanding the inevitable limits of one's skill and equipment, and operating accordingly, is key. A 16 disc set of brakes just isn't going to improve things enough, IMHO, to allow someone like myself to ride in a way that comes anywhere close to needing them. We can "what if" scenarios all we want but the fact will remain, there are riders adaptive enough to operate modest equipment safely forever and a day, and riders who will summarily pile up the most over-designed for purpose machines that money can buy.
Ever watch those YouTube vids of bike accidents and wonder why in hell the rider couldn't have seen it coming ? I certainly have, by the dozens, and I'm not very long in the saddle. Brakes can only do so much.
#98
04-04-2016 | 08:15 AM
Road Master
Joined: May 2008
Posts: 809
Likes: 22
From: Olathe KS
What part of keeping a stock brake system, if it happens to outperform many sportbike brakes in street riding, involves "skimping"? Or are some people still clinging to fantasies that their street-driven Harleys are race bikes, benefiting from brakes that will pull them down repeatedly from 160 mph? LOL
Hello, brake setups that work well for racing don't necessarily work well at all on the street. There can be some tradeoffs. For example, brake pads designed to work well at high temperatures can feel pretty slick, and give poor stopping power before they are brought up to design temperature. But if you don't mind driving around on the street, dragging the brakes all the time to keep them heated, maybe they would work OK.
It's a little like assuming that since most race bikes are making their best power over 10 thousand rpm, that's where you'll be getting the best power out of your Harley engine.
If you don't "skimp" on tires, are you running racing compound slicks on the street at all times when the roads are dry, for maximum traction and braking? And switching back and forth between those, and grooved "rain" racing tires, depending on the weather? If not, doesn't that amount to "skimping", versus the safest and and best performing setup?
Or how many of you run Y or Z rated tires, so you'll have the right tire in place whenever you drive your Harley 186 miles per hour?
Hello, brake setups that work well for racing don't necessarily work well at all on the street. There can be some tradeoffs. For example, brake pads designed to work well at high temperatures can feel pretty slick, and give poor stopping power before they are brought up to design temperature. But if you don't mind driving around on the street, dragging the brakes all the time to keep them heated, maybe they would work OK.
It's a little like assuming that since most race bikes are making their best power over 10 thousand rpm, that's where you'll be getting the best power out of your Harley engine.
If you don't "skimp" on tires, are you running racing compound slicks on the street at all times when the roads are dry, for maximum traction and braking? And switching back and forth between those, and grooved "rain" racing tires, depending on the weather? If not, doesn't that amount to "skimping", versus the safest and and best performing setup?
Or how many of you run Y or Z rated tires, so you'll have the right tire in place whenever you drive your Harley 186 miles per hour?
If it's strong enough to lock the wheel with one, do you really need two? The only advantage I could see is threshold braking may be better, but that only matters when you know your surface.
#99
04-04-2016 | 08:46 AM
I really dont understand why folks are still fighting over theory and writing these books...
Last edited by cvaria; 04-04-2016 at 08:52 AM.
#100
04-04-2016 | 09:06 AM
Road Captain
Joined: Oct 2015
Posts: 706
Likes: 28
From: Alaska
P.S. I loved the video montage clip you posted.
Last edited by AKFXD; 04-04-2016 at 09:10 AM.