HPI 39T High Speed Idler Gear... Increase of up to 20mph!?

[Jahay]

Hi everyone....

I been mentioning the notion of a high speed idler gear that was released by HPI...
Now when it comes to gearing i am a little ignorant and need some help...

People on here have been saying that an idler gear doesnt do anything hence "idle" but in a Savage Flux single speed tranny, it def has more of a role....

Gearing for a savage flux 44ts/25tp nets you around 63mph top speed

Proof... Plus i know his gearing as we have been chatting
Savage at 62mph... 44/25
http://www.youtube.com/watch?v=JuTMW8UPqlE

First run using 44/25 PLUS hpi 39t high speed idler gear 66mph
http://www.youtube.com/watch?v=FxdmPlT3C-g

4th Run with the same gearing... He has now wrapped flishing line around his tires to stop ballooning... Speeds reached : 74.3mph.
http://www.youtube.com/watch?v=eG_KQWR4bHY

Most recent 5th run... Hasnt changed anything since the last run... And has managed to his 79.3mph!!!!
http://www.youtube.com/watch?v=Q8pydXrZqng


I think this is really impressive... Could someone explain how this idler gear works? because it is obvious its not what people thought. People say its like having a 2 speed tranny, and instead of the flux driving in the first gear it is now stuck in 2nd gear... Yes it takes a little of your bottom end away, but considering the torque some of these motors have, i doubt that would make much of a difference anyway... If anything it would make these trucks more drivable at low speeds with less wheelies.

Anyone care to chime in... Here are the facts... need an explanation.

THANKS