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+--- Thread: 6th gear....speed vs rpm (/showthread.php?tid=2301)
RE: 6th gear....speed vs rpm - Pterodactyl_imp - 09-07-2014
(09-07-2014, 02:06 AM)The ferret_imp Wrote: Great ride! .... As usual
Talking about braking..Randy I believe there is some residual transfer of weight when stopping with the rear brake only (hard to deny physics) but nothing like the transfer of weight on the front end when the front brakes are applied. Which are why larger diameter, multi piston caliper dual discs are on the front, and smaller diameter single disc with fewer piston calipers are on the rear.
Ptero... Yes there is a big difference between " testing" and full emergency panic braking. Not disputing Keith Code's numbers, as I have heard other numbers as well, but whether the numbers are 90/10 80/20 70/30 whatever the numbers are, it is important that the rear brakes function properly. When guys tell me they never use their back brakes, only the front, I just have to wonder why they would give up that extra measure of braking voluntarily. Why would you give up even 10% (using Codes figure) of the braking power the rear brake provides? If rear brakes were not vitally important, why would MotoGP bikes have them? They could save weight and complexity by eliminating a disc, a carrier, a caliper, a hose, a master cylinder and fluid, yet as powerful as the huge front brakes on MotoGP bikes are, they still have rear brakes and I'm guessing when they hurtle down a front straight to a tight hairpin curve, the MotoGP riders use them. Braking hard with the front unloads the weight on the rear making the rear brake less efficient, sometimes to the point of lifting the rear wheel off the ground, but in a non emergency situation ( heck even in an emergency situation) using BOTH brakes is the most efficient way to stop, and both should be strong.
Strong brakes are more important to me than having 100 horsepower, or a motorcycle that will run over 100 mph. I rarely (virtually never) ride that fast, but I often have to brake hard. Several times in the last few days, once when I came around a corner only to find stopped cars in my lane due to a stopped school bus, and another when an old man obviously didn't see me and pulled out in front of me. I rely on my brakes saving my life.
I don't want my rear brake to lock up. I dont want my front brakes to lock up either. A skidding motorcycle is an out of control motorcycle (which is why ABS is such a good safety feature) but I want the strongest front and rear brake I can get prior to them locking up, or prior to the abs kicking in, whichever comes first.
The easiest remedy for brakes that are not as efficient as they should be are multi fold. # 1 bleed the system to eliminate any air in the system. #2 deglaze the brake pads # 3 clean the disc #4 replace the stock pads with a pad with more bite #5 replace rubber lines with stainless lines after that its replace disc, replace caliper, try better brake fluid, depending on how much braking power you desire.
Mate I don't think I have made myself clear. In a steady state condition, that is the motorcycle is at a constant speed, say 30mph, the weight of the bike is distributed approximately 50/50 between front and rear wheel. Lets say you now want to initiate an emergency stop using the rear brake only on a standard road surface. Don't ask me why you'd do that, except, maybe, to see how effective the rear brake is. There is good friction between rear rubber and road surface and, assuming the bike is kept tracking straight, little likelihood of the rear wheel locking. The bike eventually comes to a stop. The rider's perception is that the rear brake is not effective. Guess what? That's correct. Why?
Well, the brakes are a linked system on any bike that has front and rear brakes. "What?", you say. No I'm not mad, they are linked either by the rider applying both front and rear, or by a mechanically linked system, and are meant to be used as such, a system. Not one at a time or one only. And I'm not talking here about trail braking at speed or rear brake only application during slow speed manoeuvring. I'm talking about bringing the bike to a stop as expeditiously as possible.
So in the example above both brakes are applied, as they should be, both front and rear, and, assuming a manual system, as firmly as possible. What happens? There is a rapid and dramatic C of G change due to deceleration and the riders weight now transferring from the pegs to the bars. This now results in, using Code's numbers, a front/rear weight distribution of up to 90/10. 70/30 would do as well because the principle is the same. The rear wheel now has a greatly reduced responsibility in the endeavour of preventing you, and your beloved CB, face planting that U-turning soccer Mum (no offence meant ladies, soccer Dad would do). In fact at maximum pedal effort the rear wheel may, no, it will, lock up. Do you need any more braking than that? No. In fact it's too much. That's why ABS compensates for a heavy foot and prevents lock up.
If you don't believe that reduced weight on the wheel means the brake needs less effort to lock the wheel then consider this. Put your foot on the ground with all your weight on it. Now get your dearly beloved to attempt to kick it out from beneath you. Too hard to do? Yes. Now take most, say 90 per cent, or 70 if you like, weight off that foot and get dearly beloved to try again. Too easy. Without support you fall on your backside. The reason I've given that illuminating glimpse of the obvious is to avoid discussion regarding coefficients of friction (and traction) (and contact patches) clouding the issue as it has in another thread.
So the rear brake, to be effective, does not need the massive stopping power of the front brake. In fact, if it had that power the risk of lock up through heavy footed buggers like me misapplying them is a real factor. In the case of the CB in a full on emergency stop then max effort will produce a lock up. I know, I've done it. Need any more rear brake than that? No, less actually. You are not giving up anything. In summary, and to paraphrase Goldilocks, the CB brakes are "Just right".
Cheers, and now it's my turn for a ride.
Ferret, just read your previous, posted while I was typing. The brakes are nicely balanced, that's why you never noticed. This discussion has produced brake hypochondria. You know, like oil virus. Worse than Ebola.
RE: 6th gear....speed vs rpm - the Ferret - 09-07-2014
Have to digest that awhile lol
Have a good ride, I'm going to bed
RE: 6th gear....speed vs rpm - Lord Popgun - 09-07-2014
The service manager rode mine and locked it up right in the parking lot. Skidded the tire and all. Said it was good and he was done. Said Honda doesn't pay him to look for problems. That was not real world braking.
I went straight to the part counter, bought some brake fluid and went home and bled out a bunch of air (does air come in bunches?). Just being able to lock up the brake doesn't mean its right, or good.
RE: 6th gear....speed vs rpm - Pterodactyl_imp - 09-07-2014
(09-07-2014, 11:25 AM)Lord Popgun_imp Wrote: The service manager rode mine and locked it up right in the parking lot. Skidded the tire and all. Said it was good and he was done. Said Honda doesn't pay him to look for problems. That was not real world braking.
I went straight to the part counter, bought some brake fluid and went home and bled out a bunch of air (does air come in bunches?). Just being able to lock up the brake doesn't mean its right, or good.
Maybe, but do you want any more brake than what is required to lock the wheel? If so, what are you going to do with it?
. You are right though, a parking lot test is near to useless. The energy (kinetic) required to be dissipated in a stop is calculated as:E = 1/2mv²
The mass of the bike is constant. Let's say the bike weighs in at 100kgs, then at 10mph the energy to be dissipated is 5000 units. At 60mph the kinetic energy of the bike is not six times as much, that is 35000units. It is, in fact, 180,000 units. The energy is best dissipated by friction produced by a rolling tyre, not a skidding one. Hence ABS.
If you practice an emergency stop on the CB, does the bike feel as though it lacks stopping power? In my opinion, and that of many professional test riders who are a damn sight more informed than me, the brakes are rated as very good. The bike is meant to be stopped by a well balanced (if interested read my post above) combination of front and rear brake force. The CB has that.
Cheers.
RE: 6th gear....speed vs rpm - Randy B - 09-07-2014
(09-07-2014, 12:06 PM)Pterodactyl_imp Wrote:(09-07-2014, 11:25 AM)Lord Popgun_imp Wrote: The service manager rode mine and locked it up right in the parking lot. Skidded the tire and all. Said it was good and he was done. Said Honda doesn't pay him to look for problems. That was not real world braking.
I went straight to the part counter, bought some brake fluid and went home and bled out a bunch of air (does air come in bunches?). Just being able to lock up the brake doesn't mean its right, or good.
Maybe, but do you want any more brake than what is required to lock the wheel? If so, what are you going to do with it?
E = 1/2mv²
The mass of the bike is constant. Let's say the bike weighs in at 100kgs, then at 10mph the energy to be dissipated is 5000 units. At 60mph the kinetic energy of the bike is not six times as much, that is 35000units. It is, in fact, 180,000 units. The energy is best dissipated by friction produced by a rolling tyre, not a skidding one. Hence ABS.
If you practice an emergency stop on the CB, does the bike feel as though it lacks stopping power? In my opinion, and that of many professional test riders who are a damn sight more informed than me, the brakes are rated as very good. The bike is meant to be stopped by a well balanced (if interested read my post above) combination of front and rear brake force. The CB has that.
Cheers.
Maybe, but do you want any more brake than what is required to lock the wheel?
No, but having a consistant brake because it was bled properly it at the top of my list.
RE: 6th gear....speed vs rpm - OldF7Guy_imp - 09-07-2014
(09-06-2014, 09:53 PM)The ferret_imp Wrote:(09-06-2014, 02:50 PM)OldF7Guy_imp Wrote:(09-06-2014, 12:27 AM)The ferret_imp Wrote: Ok just got in from a ride. It is confirmed..again..my rear brake sucks. The rear brake on my wife's scooter is much, much better. 30 mph, 40 mph no front brakes, pull in the clutch, push the rear brake hard and slooooooowly come to a stop. Just a wimpy rear brake. I must have tried it 1/2 dozen times. One particularly hard rear pedal mash made the abs kick in one time, felt like a chain skipping a tooth on a sprocket. Not like in my car where it cycles several times..bang, bang, bang, bang..it was just one bang on the bike. Thank goodness for exceptional front brakes. Again, 10 mph or less the rear brake seems to feel good. Just not any good at helping haul it down from speed.
Can't wait until the rally to compare bikes with others. ( if I don't fix mine before then)
Not questioning you because I have a lot of respect for your opinion but what are you using as a point of reference? Your ST1300 maybe? I believe you.
Could you elaborate a little more? My 750 has tons better back brakes than my previous sportster but when you get to the limits you realize it was not as good as you thought or wanted. It locks up easier than you think it will.
Again, respect your years or riding and experience, but to have 2 years in a row that you think are lousy are pretty incredible and one wonders what you deem decent and where yoiur point of reference is on good brakes. THis matters to me because I want good brakes.
Hope this did not come off wrong. Its just an important part of the CB11 to me and I trust you to be honest.
No, I understand what you are saying, but obviously you can tell your Nighthawk rear brake was better than your Sportsters. An experienced rider can tell when a rear brake ( or front) is effective or not if they have ridden several bikes. I couldn't use the ST 1300 for reference because it has linked brakes so when you try and use rear only you also get some front. Skews the results.
I think if you've ridden enough bikes (and I have literally ridden hundreds) you know when the rear brake feels strong or doesn't. My 750 Nighthawk drum brake was better at slowing the bike (up to the point of lock up and skid) than either of my CBs, but the single front disc was rather weak. My wife's Majesty scooter has a great rear brake and will slow the scooter quickly, stronger than her front brake too. I have had 3 other experienced riders, my brother, my son and my sons father in law, ride my 13 and test the rear brakes and all said the exact same thing.."yea, not much there". Of course the Honda rep said it was fine. This is the first time I tested the 14s rear brake by itself. I really thought it was better than my 13, but it's not. Honestly, take it up to 30 mph, pull in the clutch, step hard on the rear brake and it just slows down agonizingly slowly. It just keeps rolling until it gets down to about 10-15 mph, then it starts to stop. To me it's scary, how ineffective it is. Thank goodness this motorcycle has outstanding front brakes.
Thing is, I'm not the only one who feels the rear brakes on their CB is ineffective. There were others in 13, and there are at least 2 others on 14s who also feel their rear brakes are not as strong as they should be. I may leave mine like this and let others at the rally ride it and compare, but by then I would be out of warranty, so I may go ahead and take it in and have them bleed the brakes and see if it's any better.
No, I understand what you are saying, but obviously you can tell your Nighthawk rear brake was better than your Sportsters. An experienced rider can tell when a rear brake ( or front) is effective or not if they have ridden several bikes. I couldn't use the ST 1300 for reference because it has linked brakes so when you try and use rear only you also get some front. Skews the results.
I think if you've ridden enough bikes (and I have literally ridden hundreds) you know when the rear brake feels strong or doesn't. My 750 Nighthawk drum brake was better at slowing the bike (up to the point of lock up and skid) than either of my CBs, but the single front disc was rather weak. My wife's Majesty scooter has a great rear brake and will slow the scooter quickly, stronger than her front brake too. I have had 3 other experienced riders, my brother, my son and my sons father in law, ride my 13 and test the rear brakes and all said the exact same thing.."yea, not much there". Of course the Honda rep said it was fine. This is the first time I tested the 14s rear brake by itself. I really thought it was better than my 13, but it's not. Honestly, take it up to 30 mph, pull in the clutch, step hard on the rear brake and it just slows down agonizingly slowly. It just keeps rolling until it gets down to about 10-15 mph, then it starts to stop. To me it's scary, how ineffective it is. Thank goodness this motorcycle has outstanding front brakes.
Thing is, I'm not the only one who feels the rear brakes on their CB is ineffective. There were others in 13, and there are at least 2 others on 14s who also feel their rear brakes are not as strong as they should be. I may leave mine like this and let others at the rally ride it and compare, but by then I would be out of warranty, so I may go ahead and take it in and have them bleed the brakes and see if it's any better.
Appreciate the reply. If both CBs were worse than your Nighthawk then something is up. I wish I had better front brakes. I had to literally stand on both one time full out and the weight transfer to the front and soft sprung NH got the back light and I was on/off with locking the rear. That is where abs could help. I was right at the edge but hung on to it and it could have been ugly.
Whats funny is that my old Sporster had a rear disc brake and of course the NH had a drum. I wonder how a drum can be so much better but it truly is. Similar weight ect or close. Keep us posted because like you brakes are as important to me as just about anything.
RE: 6th gear....speed vs rpm - Pterodactyl_imp - 09-07-2014
(09-07-2014, 01:02 PM)Randy B_imp Wrote:(09-07-2014, 12:06 PM)Pterodactyl_imp Wrote:(09-07-2014, 11:25 AM)Lord Popgun_imp Wrote: The service manager rode mine and locked it up right in the parking lot. Skidded the tire and all. Said it was good and he was done. Said Honda doesn't pay him to look for problems. That was not real world braking.
I went straight to the part counter, bought some brake fluid and went home and bled out a bunch of air (does air come in bunches?). Just being able to lock up the brake doesn't mean its right, or good.
Maybe, but do you want any more brake than what is required to lock the wheel? If so, what are you going to do with it?
E = 1/2mv²
The mass of the bike is constant. Let's say the bike weighs in at 100kgs, then at 10mph the energy to be dissipated is 5000 units. At 60mph the kinetic energy of the bike is not six times as much, that is 35000units. It is, in fact, 180,000 units. The energy is best dissipated by friction produced by a rolling tyre, not a skidding one. Hence ABS.
If you practice an emergency stop on the CB, does the bike feel as though it lacks stopping power? In my opinion, and that of many professional test riders who are a damn sight more informed than me, the brakes are rated as very good. The bike is meant to be stopped by a well balanced (if interested read my post above) combination of front and rear brake force. The CB has that.
Cheers.
Maybe, but do you want any more brake than what is required to lock the wheel?
No, but having a consistant brake because it was bled properly it at the top of my list.
Maybe, but do you want any more brake than what is required to lock the wheel?
No, but having a consistant brake because it was bled properly it at the top of my list.
That's true Randy. However I get the feeling that if a bike has stopped well for a couple of thousand miles and then, after a rear brake only "test", due to brake hypochondria or whatever, the owner thinks the rear brake is not "effective", then it's probably the brain that needs bleeding, not the brake system.
Air does not suddenly "appear" in a well designed brake system. And I would suggest that includes the CB. I don't see a class action against Honda for delivering brakes complete with air being successful. Brakes may require bleeding after a pad change, but not if you're careful. Brakes will require bleeding after, or as part of, fluid change or component change. If a brake system has trapped air the brake performance will certainly be consistent. Consistently bloody terrible!
Cheers
By the way, I'm often wrong.
RE: 6th gear....speed vs rpm - Randy B - 09-07-2014
No worries man.
RE: 6th gear....speed vs rpm - xNE0x_imp - 09-07-2014
Wait a tick, did I miss something? You are making a rear braking comparison of the CB1100 to a scooter? That's not a fair comparison.
Let's go back to basics:
https://www.youtube.com/watch?v=_MOQJr9ovY0
If this does not help, there are a variety of different pads and materials you can try.
RE: 6th gear....speed vs rpm - Pterodactyl_imp - 09-07-2014
(09-07-2014, 02:20 PM)xNE0x_imp Wrote: Wait a tick, did I miss something? You are making a rear braking comparison of the CB1100 to a scooter? That's not a fair comparison.
Let's go back to basics:
https://www.youtube.com/watch?v=_MOQJr9ovY0
If this does not help, there are a variety of different pads and materials you can try.
No mate, you've got it. Thanks for that. It's part, and only part, of what I have been trying to say in too many words in previous posts.
Have a cigar
. Cheers