small CC bikes with single front brake disc. less braking power? | GTAMotorcycle.com

small CC bikes with single front brake disc. less braking power?

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motoride777

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i noticed some 250, 300 and 500cc bikes with only a single front brake disc, but the weight of the bikes are still close to about 400lbs. does that mean these bikes don't brake as well? i.e. longer brake distance in an emergency braking situation...?
 
Yes. But number of discs is not always the full story, there are number of pistons, pad area, swept area, and you do not want the braking capacity to exceed the front tire capacity to brake or you will just lock.
On the other hand, there are many Youtube crashes of SS rider flying over the bars in a panic stop.
 
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Not necessarily... there are more variables.
What size is the single disk? How many pistons in the caliper? Are the pistons opposed? Is it a quality brake system?
All my race bikes, from a GP250 to a 850 Norton Commando factory race bike, have a single disk... and I have never needed/wanted more.
 
CafeRay said:
An 883 is 560lbs with a single disc.
Click to expand...

Sports bike with a single disc vs a cruiser with a single disc are apples and oranges, because of low center of gravity on the cruiser (and obviously completely different weight distribution).
 
bitzz said:
Not necessarily... there are more variables.
What size is the single disk? How many pistons in the caliper? Are the pistons opposed? Is it a quality brake system?
All my race bikes, from a GP250 to a 850 Norton Commando factory race bike, have a single disk... and I have never needed/wanted more.
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Absolutely right. Way too many variables to make a blanket statement that single disk braking systems are less effective. I know on my CBR500 if have no issues getting the back end to lift under hard braking.
 
OP: You're probably thinking that the bike will pull to the side where the disc is located. Which is simply not true at all.
 
viperz said:
sports bike with a single disc vs a cruiser with a single disc are apples and oranges, because of low center of gravity on the cruiser (and obviously completely different weight distribution).
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stop interfering with ray's altered reality with facts!
 
As a general statement it's safe to say the bikes as described in op have less outright braking power than double disc setups. My single Buell is ok too.

320mm brake upgrades on my sumo conversions provide a level of braking rarely needed. Nice to have tho.
 
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My RS125 is single disk while my 650R was double disk. The RS125 brakes better.
 
The following is my opinion based on a little physics... Think heat...

Most cases modern bikes with single front disks can brake harder than the tire can grip (lock the front wheel). The ability to lock the wheel will depend on what others have noted above and some other items (disk size, master cylinder mechanical advantage, number of pistons, pad material, hand strength, etc.). Once a braking system can lock the front wheel more brakes are not going to lock it more... This even applies to abs (although they system stops it from locking the brake has the strength to lock it). The next question is heat and multiple stops...

Now the advantages, the bigger the system (larger disk, more disks, etc.) will encounter less heat during said hard stop (the stopping energy as heat is more spread out or shared). So the next hard stop right after the one you just did they will have more heat reserve, after repeated hard braking the single front disk will no longer be able to lock the brakes due to heat (brake fade), the dual disk, all else being equal, this will happen later. Important on the track, debatable on the road (although QEW 130 down to 30 back to 130, down to 30 is not uncommon these days).

Now many of the smaller CC bikes also have smaller front tires, smaller front tire means easier lock... So not only are they saving money it may be more practical given dual disks could be total overkill given less front traction.

Dual disk might also provide better feel when hot as well (better modulation preventing lock), but there are many additional variables here. Less hand effort on dual disk usually, again variables. On the other hand many a novice has made the trip over the bars with a panic fist full of front brake (dual disk).

Given the choice, I prefer dual disk for function but a single can get the job done within certain parameters. Dual disk also looks more racer...

For cruisers, it is unlikely they will ever see a track (road course) so they are not as worried about the heat issue noted above. They tend not to ride as fast on the highway as well. The core market may be more tolerant of weaker brakes (they are not into the aggressive riding style). Even with much more weight the single disk when cold or cool can lock up that front wheel.
 
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unL33T said:
My RS125 is single disk while my 650R was double disk. The RS125 brakes better.
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Yeah well I should hope so, considering the RS125 is probably a good 180lbs lighter than the 650. Put one of your buddies on the back of the 125 and test again?
 
Some reality numbers:

CBR250 60-0: 143.4
Ninja 300 60-0: 141.8

http://www.motorcycle-usa.com/114/15986/Motorcycle-Article/2013-Honda-CBR250R-Comparison.aspx

But it's hard to compare between tests because of rider weight and ambient conditions.

MCN got an 883 to stop in 134ft, while a Bonneville does it in 115ft, both single disc. (Ford F150 is 132ft).

So yes, these small bikes have weaker brakes, which is why the first upgrades should be Galfer brake lines and better pads, along with softer tires.
But no, it's typically a louder slipon, levers and tail tidy.
 
backmarkerducati said:
Now many of the smaller CC bikes also have smaller front tires, smaller front tire means easier lock... So not only are they saving money it may be more practical given dual disks could be total overkill given less front traction.
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The smaller bikes are targeted to novice riders. More powerful front brakes will likely just lead to more locks and crashes, which ABS won't fix on turn-in. In that group, weaker brakes may be safer.
 
backmarkerducati said:
The following is my opinion based on a little physics...

Even with much more weight the single disk when cold or cool can lock up that front wheel.
Click to expand...

I believe shallow fork angle makes it easier to lock the front brake.
 
Have you ever ridden a motorcycle... or do you just cruise ads on the internet?
From your link:
"The Bolt also stops more quickly, thanks to high-tech wave rotors front and rear. In contrast, the Iron feels under-braked, with a dead sensation at the lever and a wooden feel to the under-sprung front end. The Sporty’s rear brake, however, is not as inclined to lock up, an all-too-common event when braking hard on the Bolt."
To start with, the ad is comparing Harley's budget bike to Yamaha's higher spec bike. Of course it will lose. The yamaha has "high tech rotors", where as the Harley has the wrong master cylinder.
See where it says the rear brake on the Harley won't lock up? THAT IS BECAUSE OF THE DIFFERENT FRAME GEOMETRY. Look at the swingarm on the Harley. It is parallel to the ground. Look at the Yamaha swingarm. It is higher at the pivot than at the axle. On the Harley the virtual center of gravity of the wheel lines up with the actual center of gravity of the wheel. On the Yamaha the virtual center of gravity is in front of the actual center of gravity. That affects braking. It also affects weight transfer to the front end WHILE braking.
It's not the brakes fault the Yamaha can out brake the cheapest Harley sold. It was Harley's design. That's what post #5 said.
 
The ability to "lock" the front wheel is not a valid comparison for brakes.
It is simple to lock the front wheel; just jam a hockey stick into the spokes. That'll lock the front wheel.

What you want is the ability to modulate the brake, to achieve maximum braking levels WITHOUT locking the wheel.
 
bitzz said:
Have you ever ridden a motorcycle... or do you just cruise ads on the internet?
From your link:
"The Bolt also stops more quickly, thanks to high-tech wave rotors front and rear. In contrast, the Iron feels under-braked, with a dead sensation at the lever and a wooden feel to the under-sprung front end. The Sporty’s rear brake, however, is not as inclined to lock up, an all-too-common event when braking hard on the Bolt."
To start with, the ad is comparing Harley's budget bike to Yamaha's higher spec bike. Of course it will lose. The yamaha has "high tech rotors", where as the Harley has the wrong master cylinder.
See where it says the rear brake on the Harley won't lock up? THAT IS BECAUSE OF THE DIFFERENT FRAME GEOMETRY. Look at the swingarm on the Harley. It is parallel to the ground. Look at the Yamaha swingarm. It is higher at the pivot than at the axle. On the Harley the virtual center of gravity of the wheel lines up with the actual center of gravity of the wheel. On the Yamaha the virtual center of gravity is in front of the actual center of gravity. That affects braking. It also affects weight transfer to the front end WHILE braking.
It's not the brakes fault the Yamaha can out brake the cheapest Harley sold. It was Harley's design. That's what post #5 said.
Click to expand...

blah, blah, blah, the front brakes are crap, which is why they did a major change for 2014.

134ft vs 115 ft is the difference between stopping and waking up eating hospital food.

BTW, the MSRP on a "Budget" 883 Iron and the "higher spec" Bolt are about the same. Give me what your smoking, I like your reality better.
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