I can buy a set of UR pulleys (full set 3 pulleys no belt) for $240 local or I can buy a UR crank pulley with belt for $220 shipped. If you guys were in my situation, what would you do? Are the other two pulleys necessary? THanks and please let me know ASAP

 

might as well get the full set for the same price.
-GP-

 

if you underdrive the pullies don't all of them have ot be underdriven?

 

show's how much you know about pulley's atlantic...................




^BOOM^
-GP-

 

the rest are all accessory belts, they do nothing.

Edit: * i meant accessory pulleys

 

he's not talking about the belts, he's talking about the pulley's, they are accesory pulley's that are lighter.
-GP-

 

I went with the set.. if you get one, why not get the set?

 

i've never heard of ONLY the crank pulley being sold as an underdriven pulley and the others remaining unchanged.

Heck, you'd have to change them because the new crank pulley would require a new belt, and the belt ?wouldn't? fit on the other stock, non-underdriven pulleys........

 

the rest does nothing.... but for the same price just get the whole thing...

 

Purely lightened pullies do nothing. The only noticeable gains come from underdriving.

 

The one with all the gains is the crank pulley not the other accessories.

 

ok, that's why it's been proven that for every lb. of weight you take off the crank shaft you gain 1-2 hp. In this case you lose atleast 4lbs.

lets see some evidence of no gains of purely lightened pullies to back up your statement's mechee.
-GP-

 

roh oh, he's going to pull out his mechanical engineering formulas on you (there've been HUGE discussions where he tries to convince people that lightening does nothing)

 

Well , although they cost similar, 3 pulleys = more install money compared to just installing one. And that crank pulley price is WITH the belt while the other (pulley set) does NOT come with belts. SO I think iwill think real hard...

 

Your statements have not been proven anywhere, period. They don't even make sense from a physical point of view. Your "gains" will vary as a function of the angular acceleration of the component, which varies as a function of engine power output and load (which changes in every gear). The fact is that for the relatively small angular acceleration rate of our motor in all scenarios, the amount of torque required to accelerate such small inertias hanging off the engine is virtually nothing.

If you're truly interested in physically why this is the case, I have derived all of it here: http://www.stanford.edu/~mpg/lighten...omponents.html