Wednesday, May 09, 2012


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2wheelsonly! said...

Drop a Disc?

Flash2Crash said...

Any rotating mass you can get off your wheels will do more to improve handling than about anything. But, I loves me some braking power!

2wheelsonly! said...

Any "mass" upon a wheel would de-facto have to "rotate" with the wheel, yes?

Unsprung Weight is what you speak of, good sir. The lighter the wheel assemblies, the quicker and easier to flick the bike it gets.

But Flash, I'm thinking the disc was removed to show-off the rim.

Nice RSD Performance Machine Rims.
Lighter than stock, why drop the disc? The reduction in unsprung weight would not come near off-setting that precious braking power!

At least 80% of that bikes braking force lies in the front 2 discs. So, you'd lose almost HALF the braking power!

2wheelsonly! said...

So, you'd lose almost HALF the braking power!

To look KEWL at stop-lights?

Fermp That Noize!

2wheelsonly! said...


The farther mass is from a wheels axis/axle the greater the force needed to overcome rotational inertia.

So, as we know, all other things being equal, a 16" rim leans quicker than a 21" rim.

Because the 16's mass is closer to center than the 21. Now, if the 16 weighs twice as much as the 21?

He lost weight with those rims, no need to drop a disc.

Lighter rims are the a way better investment than pipes and such!

sd.corruptmind said...

could be to show the rim... or could be he couldnt afford the second rotor lol

martvol said...

And lets not forget this is not a track. Not everyone drives white nuckle. Maybe it is a former Harly rider that made an impulse purchase. Now he is making it shine. Not to much chrome for them things. He doesn't need the braking power, because, as all you know, he isn't going that fast to begin with.

2wheelsonly! said...

corrupt said- "could be to show the rim... "

that's what I said above- "But Flash, I'm thinking the disc was removed to show-off the rim."

and- "To look KEWL at stop-lights?"

I believe that is the stock disc, meaning he has the other one and is foolish enough not to use it. Not to save money/weight.

2wheelsonly! said...

Okay, martvol, please let me know if you wrote that paragraph in jest or in all seriousnes.

Was it meant to be sarcastic or not sarcastic?

p.s. My sincere thanks to any/all Dragoneers who join in any discussions!

I know sometimes comments can be tough to interpet. Was he being a cocky ass, is he serious, being funny, etc?

For the Record- I do NOT think I am anyone special or that I am better than anyone else. We are ALL different and it's all good!

martvol, please don't forget to let me know about that sarcasm thang..

Pilote Ancien said...

@2W: Stumbled across some rotating inertia while looking for Alfa Romeo TZ vids and thought of you.
Vid runs 7 mins., it took me over 3 to get bored.
Don't know what the model number refers to. Liters and revs too small. Maybe the tons of concrete required for the base.

martvol said...

I wrote it with a sharp pointed stick.

martvol said...

Well, the computer equivalent.

dog said...

Spend the extra cash for a trick perimeter brake system and be done with it.

Flash2Crash said...

2wheelsonly... unsprung weight allows the suspension to move more freely, rotating mass makes the bike want to go straight.

2wheelsonly! said...

Not so, Flash.

Unsprung weight is just that..unsprung.

Thereby having NO effect on the suspension because it is "unsprung" weight. No Effect on the Springs (unsprung) at all.

So, by definition it doesn't affect suspension. Spring rates, compression/rebound damping, fork-oil viscosity, etc are what makes suspension move stiffer or looser.

Unsprung weight is just another way of saying less wheel mass.

The lighter the wheel (less mass)assemblies the easier to change direction.

And the closer to center mass is on a wheel assembly the better.

2wheelsonly! said...

Overcoming resistance to stay in a straight line is easier with lighter wheels.

Flash2Crash said...

au contraire, mon frer. Less unsprung weight allows the wheels to move up and down more freely. The suspension doesn't allow the bike to move. It's purpose is to keep the bike level and let the wheels move. Less unsprung weight includes axle, caliber, brake pads, lower for tubes, etc. Those are the things that are 'unsprung'. The bike itself, is 'sprung'. Yes, the rotating masses are unsprung, but have more effect on turning resistance than the fixed items. Think gyro.

Pilote Ancien said...

Looks here like everything's been said, but not by everybody (MO Udall's observation about Congress. Seems like people are saying similar things different ways.
So PA weighs-in too:
1) The less rotating mass, the less force needed to overcome the gyro effect, no? Thus more nimble handling.
2) The less unsprung mass, the less spring and shock rate to push back on it. Or a stiffer package (especially rebound damping) will keep the tire in more constant contact with the road. Thus grippier handling.
3) The higher the ratio of sprung mass to unsprung, the more nimble the bike will be. But total mass trumps the ratio: the lighter the bike the better for nimble and grippy handling.
4) In braking, the mass of the disc(s) is relatively unimportant compared to the total mass of the bike and braking force. Reducing rotation speed by converting it into heat trumps the importance of the mass of the brake disc (unless it's a manhole cover).

What am I missing here?

2wheelsonly! said...

About the same, I agree.


Love #4, that's my WHOLE point!

The ONLY thing being gained by removing one front disc is longer Braking Distance!!