Track Wives tales | GTAMotorcycle.com

Track Wives tales

bigpoppa

bigpoppa

Well-known member
Cant remember where I heard this, but i've heard this enough times from racers/track guys that it stuck..the old saying about 1 lb = 7 hp....

Track guys/racers..

Any truth/validity to this? Perhaps 1 lb lost feels like 7 hp gained? Where did this come about?

Gracias
 
For acceleration purposes ...

Take the weight of your bike (in track-ready condition), add the weight of you. Divide the total by how much power your bike makes. That's the power-to-weight ratio. Adding or subtracting that much weight is equivalent to 1 horsepower. In my particular case, for my race bike, it's about 9 pounds per horsepower.

Aero drag / top speed, the relationship is not so simple.
 
Brian P said:
For acceleration purposes ...

Take the weight of your bike (in track-ready condition), add the weight of you. Divide the total by how much power your bike makes. That's the power-to-weight ratio. Adding or subtracting that much weight is equivalent to 1 horsepower. In my particular case, for my race bike, it's about 9 pounds per horsepower.

Aero drag / top speed, the relationship is not so simple.
Click to expand...
Congrads on your win this weekend.
 
and here I was all ready to tell about my awesome wife too :lmao:

I ride a 260cc 4-stroke motorcycle that weighs 160 pounds and I weigh 140 so my GVW is 300 pounds and I'd be guessing on the horsepower but let's call it ~25HP, what's that work out to ~12 pounds per horse? :| that horse won't even know I'm on there!
 
bigpoppa said:
Cant remember where I heard this, but i've heard this enough times from racers/track guys that it stuck..the old saying about 1 lb = 7 hp....

Track guys/racers..

Any truth/validity to this? Perhaps 1 lb lost feels like 7 hp gained? Where did this come about?

Gracias
Click to expand...
Wrong way around. It is every 7lbs = 1hp.

I know Colin Edwards said it back in the day in WSBK which is where I first heard it.

As Brian said it is purely simple math.

Take a 2017 Yamaha YZF-R6. It produces a claimed 116HP at 190KG(419lbs).

If Rider A weighs 200lbs, it is a combined weight of 619lbs. 619lbs/116hp = 5.3lbs/hp.

If Rider B weighs 220lbs, it is a combined weight of 639lbs. 639lbs/(5.3lbs/hp) = 120hp.

To maintain the equivalent hp/weight ratio Rider B would need 120hp.

The arbitrary number of 7lb/hp came from a time when bikes were heavier and made less power. However, the relationship is still relevant. As Brian stated it is obviously not that simple as there are other factors like drag that aren't taken into consideration.

Key take away: Lose weight before spending money on your engine.
 
Yay :cool: I got a combined weight of 540lbs on a 129 HP
if I can tuck in tight enough and not blow off the bike you're going to need a Y2K turbine bike.

Does it not make a huge difference if that loss is unsprung weight reduction vs rider weight loss?
I'd kind of like to lose about 5 pounds off each wheel and gain 10 in muscle mass :|
 
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Pic of my track wife to appease those who may have been lured into this thread under false pretense. :cool:
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trackwife.jpg
 
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She looks fast
 
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