Does dropping 7 lbs really equate to gaining 1hp?

[OreoGaborio]

Here's MY theory... I wanna see if you genius engineering types agree.



Take the RWHP of the bike and divide it by total (bike & rider) new weight after your diet and you'll get a HP/WT ratio.

Then multiply that number by the original weight and you get the RWHP that you would have had before the weight loss.

Follow?


So let's say your bike makes 100hp
You & your bike weigh 550lbs after a diet...
100hp / 550lbs = .181818 hp per pound.

Suppose we dropped 7lbs, so we originally weighed 557lbs...
Well that should mean, assuming we believe the 7lbs = 1hp rule, that we'd be making 101hp if we didn't lose weight, right?

.181818 x 557lbs = 101.27. So we really gained the equivalent of 1.27hp.


That sound reasonable?

[ilikenapalm]

Lose weight and go faster. Simple as that. No need for advanced mathematics to tell you how much faster you've gone, you'll know that you went faster because you've lost weight.

[Kurlon]

Here's MY theory... I wanna see if you genius engineering types agree.

Take the RWHP of the bike and divide it by total (bike & rider) new weight after your diet and you'll get a HP/WT ratio.

Then multiply that number by the original weight and you get the RWHP that you would have had before the weight loss.

Follow?

So let's say your bike makes 100hp
You & your bike weigh 550lbs after a diet...
100hp / 550lbs = .181818 hp per pound.

Suppose we dropped 7lbs, so we originally weighed 557lbs...
Well that should mean, assuming we believe the 7lbs = 1hp rule, that we'd be making 101hp if we didn't lose weight, right?

.181818 x 557lbs = 101.27. So we really gained the equivalent of 1.27hp.

That sound reasonable?

Correct, the 7:1 'rule' is just a abstraction for those who don't like to do math.

[OreoGaborio]

Lose weight and go faster. Simple as that. No need for advanced mathematics to tell you how much faster you've gone, you'll know that you went faster because you've lost weight.

Well ya, no shit but since it varies, knowing how much each pound is worth to YOU and YOUR bike can be incentive for those trying to lose weight from themselves or the bike.

[OreoGaborio]

Correct, the 7:1 'rule' is just a abstraction for those who don't like to do math.

Alright... so then lets take the same rider, but put him on a bike that's just as heavy but half the HP & see what happens...


Now your bike makes 50hp
You & your bike still weigh 550lbs after a 7 lbdiet...
50hp / 550lbs = .09090 hp per pound.

.09090 x 557lbs = 50.636363. So we only gained the equivalent of .63hp


Interesting... so weight loss makes MORE of a difference if you're on a higher powered machine to begin with.

[lrrs313]

Interesting... so weight loss makes MORE of a difference if you're on a higher powered machine to begin with.

But the rider on the 50hp machine is going to notice a .63hp gain (or 7lb loss) a lot more than the rider on the 100hp machine will notice the 1.27hp gain (or 7lb loss).

[OreoGaborio]

See that's what I always thought too... But interestingly enough it's a .0127% theoretical increase in hp for both bikes

HOWEVER...

50/557 = .089767 hp/wt ratio
50/550 = .090909 hp/wt ratio
Difference = .0011% hp/wt increase


100/557 = .179533 hp/wt ratio
100/550 = .181818 hp/wt ratio
Difference = .0022% hp/wt increase

So the more powerful bike nets DOUBLE the hp/wt ratio increase of the less powerful bike.

[Rambunctous]

The best thing is that it will corner better. Better tire life too.

[Paul_E_D]

The discipline the rider gains by losing 7 lbs and keeping it off is the real benefit to a race effort. It can't be measured, but it will yield results.

[blacklightning]

Go ahead Pete, eat the ice cream. You know you were gonna anyway. All this silly math to justify it, really?

[Trouble]

That seems entirely counterintuitive. I would expect weight reduction to be much more important and noticeable on a lower horsepower bike.

Location, location, location. If you have a beer gut the distribution of weight is closer to the track and therefor creates a lower center of gravity. Especially important on a technical track like Loudon. If you're a dork with a big head you have a higher center of gravity. Step away from the calculator Pete and pick up a beer. It'll make you go faster.

[Doc]

I am glad I have a beer gut. But Pete and his big head are still faster.

[csmutty]

That seems entirely counterintuitive. I would expect weight reduction to be much more important and noticeable on a lower horsepower bike.

Location, location, location. If you have a beer gut the distribution of weight is closer to the track and therefor creates a lower center of gravity. Especially important on a technical track like Loudon. If you're a dork with a big head you have a higher center of gravity. Step away from the calculator Pete and pick up a beer. It'll make you go faster.

Haha. I also thought this. The fact is that although it may not be as noticeable, the key to going fast on a slow bike is maintaining speed. Now even with maintaining speed there is still variation in your speed and you have to accelerate coming out of corners. That hp is more noticeable with the smaller bikes I would think because it is much harder to make up for lost ground.

Did that make any sense?

[zx1012r]

I like Pi

[lrrs313]

With a small bike you are also using max power a lot more than a more powerful bike

[sdavid]

Let me get this straight. I need to lose weight but drink more beer?

Okay, I'll try.

[Honclfibr]

Interesting... so weight loss makes MORE of a difference if you're on a higher powered machine to begin with.

Or, to say it a different way, that horsepower gains make more of a difference if you're on a low powered machine to begin with. Which is probably more easily recognizable as true.

[Spooler]

Wow, I've lost 70 lbs since the last time I rode. So I get 10 more hp this season? Awesome!

[SVRACER01]

Wirelessly posted (HTC EVO "DROID" : Mozilla/5.0 (Linux; U; Android 2.2; en-us; Sprint APA9292KT Build/FRF91) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1)

Just proves that the 50-70 lbs heavier I am than you isn't helping me.

Begs the question though. Doucette easily lost over 50lbs, but did it make him faster or just easier to go roughly the same speed?

[SVRACER01]

Wirelessly posted (HTC EVO "DROID" : Mozilla/5.0 (Linux; U; Android 2.2; en-us; Sprint APA9292KT Build/FRF91) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1)

By your math you have at least 7 HP on me based on weight alone

[SVRACER01]

Wirelessly posted (HTC EVO "DROID" : Mozilla/5.0 (Linux; U; Android 2.2; en-us; Sprint APA9292KT Build/FRF91) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1)

Interesting... so weight loss makes MORE of a difference if you're on a higher powered machine to begin with.

Or, to say it a different way, that horsepower gains make more of a difference if you're on a low powered machine to begin with. Which is probably more easily recognizable as true.

Right. Kinda like saying a pipe/filter/jet kit give a 10% increase in power. Obviously a more powerful bike will get more power from that.

[OreoGaborio]

Just proves that the 50-70 lbs heavier I am than you isn't helping me.

Begs the question though. Doucette easily lost over 50lbs, but did it make him faster or just easier to go roughly the same speed?

Yeah, Fatty. Loose some weight! (I actually gotta trim down, too. Gettin outta shape & growin a gut)

I dunno about Doucette. His fastest LWSS lap in 2010 was a 1:15.875. I'm not sure what his best was back before the weight loss, but it'd be hard to say anyway with the track changes that have occurred since. I'm also not sure if he ever went all out for a full lap cuz with Babcock out of the picture for most of the year he didn't have much competition.

[Rambunctous]

Smaller bike = smaller crankshaft and wheels = less rotating inertia means faster and better handling.

[CBR929RE]

I don't think its a good idea for me to lose weight. if I did I'd probably get blown right off the bike.

here's what a 40lb weight difference can do. both of us on 929s. he only gets me on the brakes cause he's a better rider. YouTube - attemptedpass.mov

[butcher bergs]

^^

Quit using your clutch for upshifts