KX Riders

General => In General... => Topic started by: bigbellybob on April 16, 2010, 04:19:55 AM

Title: gearing and dyno's
Post by: bigbellybob on April 16, 2010, 04:19:55 AM

i was hopping someone could tell my how gearing effects dyno number. gears r torque multipliers so would a 13-50 gear set show the same RW dyno numbers as say 14-48 gear set? im thinking that there must be a difference at the wheel. is there a optimal gearing for the best numbers at the wheel? thanks to all that help me rap my head around this.

Title: Re: gearing and dyno's
Post by: hughes on April 19, 2010, 08:55:30 AM

Horse power is horse power, I think the gearing would just change how fast / slow it gets to it's peak power. Maybe stwart can provide some insight.

Title: Re: gearing and dyno's
Post by: stewart on April 19, 2010, 09:40:45 AM

dyno s  mesure tq  and they also mesure rpm .....tq is the abilty to twist the drum on the dyno...the  2 readings give the dyno the abilty to calculate horse power ...since hp is only a calculation of the 2 readings,,if the rpm reading and the tq reading are accurate then the horsepower number is a math equation....lower gears are tq multipliers this is true but the motor rpm goes up accordingily  at whatever the gear ratio change, hope this helps/////

Title: Re: gearing and dyno's
Post by: bigbellybob on April 20, 2010, 09:30:10 AM

thanks for the replies. i was still having a hard time understanding it so i did some googling and that made me even more confused. people saying that lower gears show higher peak TQ numbers and lower peak HP numbers, people saying that HP will go up. all of them having some kind of example or story as to why this happens. even entire web sites saying that gearing has up a 14% variances on RWHP. then i found this as part of the math from dynojet. power = force x distance / time. now i get it. the lower gearing would give more force ( turn the drum easier ) but the lower gearing would also slow MPH ( take longer to travel same distance ) and thus give the same numbers.

Title: Re: gearing and dyno's
Post by: stewart on April 20, 2010, 09:41:55 AM

the only variation is if there is a slippage between the dyno swheel and bikes wheel that makes the reading  inaccurate  or if the rpm signal is inaccurate  because of using the wrong type off pickup signal

Title: Re: gearing and dyno's
Post by: bigbellybob on April 20, 2010, 10:00:04 AM

thanks stewart, i knew you were right. i was just having a hard time working it out / seeing it work in my head. especially after getting the idea of gearing changing something. i kinda fill dumb for asking now.

Title: Re: gearing and dyno's
Post by: stewart on April 20, 2010, 11:45:19 AM

do not feel dumb for asking any question i remember asking the same question myself some years back its a journey we all are on it

Title: Re: gearing and dyno's
Post by: BDI on April 20, 2010, 12:52:42 PM

Hu Hu cool. http://www.youtube.com/watch?v=BxuCeHUxoBY

Title: Re: gearing and dyno's
Post by: awak100 on June 08, 2012, 12:35:13 PM

Well interesting conversation guys.  I'm an old dinasour like my k5's yes I like torque, thats why I run big bores.  They match bore and torque.  Interesting. thanks