cush drive or no cush drive? need new wheels

[squirts1]

i'm running without one right now... bike came with PM EDGE wheels and it has no cush and im looking to buy new wheels, what do you say? I'm also going to turbo the bike within 6 months.

oh... and spun/forged/aluminum/magnesium? dont care about weight so much as a good strong wheel that won't dent easily.

the only wheels i really like are the RC comp daytona, RC comp triton, PM EDGE, and i think i like the new PVM 10 into 20 spoke wheel but i havent seen it on a bike or in person... I guess i kind of like the 5 or 6 spoke style wheels made by OZ/marvic/and all the others but they dont really grab me and several companies make wheels just like that    

[Dwight-PA]

Which ever wheel you decide upon, you're always better off if it has a cush drive. It absorbs just enough initial drive shock to reduce impact type damage. It wouldn't have been engineered into use for all these years if it weren't beneficial to use.

My advice: Purchase rims that offer a cush drive.

[turbobusa65]

squirts1 I would not recomend running without the cush drive. It helps absorb the shock out of the drive line  (chain,sprocket's, transmission, output shaft,sprocket hub,ect.) I think rim and hub are cast aluminum I would be worried I would crack something. just my opinion.  

[squirts1]

been running no cush for a year, thats the way the bike came. I just don't know any better   . cush drive/no cush drive they both have their applications. So maybe my new wheels will have a cush then   .

what's the deal with RC comp and PM wheels? ive seen the RC daytona and the PM edge and they are virtually identical... i searched a few minutes ago and saw some PM vs RC threads but none were decisive... I already knew that RC wheels use alum sprockets      .

are there good steel sprockets available for the PM? any dealers have photos and details on  similar wheels, RC daytona/ PM edge? or PVM 10 to 20 spoke new wheels?

[len]

the cush drive is their not to absorb engine pulses as much as engine pulse harmonics, thats the engine vibration thats transmitted thru the drive train, and that will fatigue over time with no apparent damage until something fails. the faster the harmonics the quicker something will fatigue to failure. Try to run the cush drive unless your just drag racing.  

[squirts1]

hey dodobird, what all am i wearing on? transmission, sprockets, the wheel, and the chain right? I thought the cush main purpose was to absorb hard launches and throttle transitions rather than vibration/harmonic vibes

[HayaBoootie]

Cush is a cheap down and dirty way to absorb shock loadings mostly due to gear changes. I cannot see it absorbing engine vibration as the slack in the chain could do that easily and if that were an issue you would expect to see failures on the drive sprocket end of things (transmission etc). Somehow I dont see vibration as having that much impact when compared to transmitting 175Hp. Do Shaft drive bikes have any bushings?

Bushing, no bushing, I can't see it makes much difference to anything other than the feel of the bike during gearchanges and pulling away.

[len]

hyabooty, WRONG-- look at a car , theirs no cush drive right?  Wrong, the springs in the clutch plate are what absorb the torsional harmonics,  Trust me on this, I'v done enough research on  propellor harmonics in aircraft I know exactly what I'm talking about. And propellors are alot more complex with vibrational nodes in the blades like a tuning fork.  Squirts, It has a effect on all parts-from the crank to the rear wheel. It will find the week part eventually. The low frequency engine pulses and shift hits, ect, have very little effect unless they themselves overload the part by just shear force. torsional vibration damage is a slow process but it is their, may take 50 miles or 50,000 miles depending on the freq. and design. And the chail will not absorb shit. for long term use, use the cush drive!  

[len]

hayabooty, look at it this way,, take a air impact wrench, they really dont produce that much power , but with the vibrational hits it produces a lot of force to loosen bolts that you would brake a wrench on. An air impact wrench is really very low frequency, the higher the frequency the more work can be done, kinda like hp, torque remains the same, hp is how fast it can be done.(( something like that))  

[BusaGeek]

quote:Originally posted by HayaBoootie:
Somehow I dont see vibration as having that much impact when compared to transmitting 175Hp.

Vibration can be the most devastating tyoe of force under the right conditions.  There are tons of stories from industry where someone put one 5 ton stamping machine on the second floor of a factory designed for 500 tons of static load.  Then they cranked the machine up to 2 stamps per second and it went through the floor -- all due to harmonics.

[HayaBoootie]

Hey Dodo,
You may be right, but I can't see it. I dont doubt that vibration is undesirable but if it were that significant I would expect to see a much better system for reducing it including a vibration isolation mount for the motor, which there is none ...

BusaGeek,
you are refering to a systems harmonic frequency. This can destroy bridges. Thats why soldiers break step when they cross a bridge. The natural freequency of a rim is probably not anything like 5KHz (motor at cruising speed) or any higher multiples.
So I just can't see it ...

[Jebakaturbogsxrpilot]

Not to technical, but this is what this author says!

 Did you get the information you want about "cush drives"? Basically any drive- train needs a shock absorber of SOME sort to stop a chain jumping off the sprocket, or smashing teeth of the sprockets on up-changes and down changes. All bikes have a shock absorber of some sort somewhere...those that DON'T have it in the back hub usually have it in some form buried in the clutch hub. It's an essential in some form, and occasionally a lifesaver. regards phylo

 

[TurboBlew]

You can get steel sprockets for RCs. They just have to be ordered     Looking this past weekend at all the turbo bikes... and virtually all of them were running aluminum sprockets.  
Lemme know if you're ready for RCs.  I can get you a deal.

[len]

hayabooty, the engine being mounted hase very little to do with the problem. The engine produces many types of shock loads into the drive train, power pulse's, balancing pulse's, ect. and these are transmited thru the entire drive train, from the crank to the rear wheel?ground. Look at it this way, take a steel punch(motor) and put it against a peice of plate steal(ground)and strike it with a hammer. 99% of the hammers force is transmitted thru the punch, strike it enough times and either the head of the hammer or punch deforms, or the tip of the punch deforms, or the plate itself. Some times the punch brakes. Now take a rubber hose and place it against the plate and strike the end, some force is  transmitted thru, but its dampend alot. you could beat forever prolly and not damage the hammer or the plate, shur the rubber will wear out, just like the cush drive does. Now think of the Hammer strikes at a very high freq. and thats what you have comeing from the engine. Some engines produce diffent harmonics, than others , depending on design. Thats why some require alot of harmonic dampaning and some require a smaller amount, but all require some.