2011 AM to EX Bump List

[Gixxerblade]

Whatever. No more trophies for me. It was a good run though.

Shut up Sean. We'll be chasing you. :)

[SV88]

I'd like to bump back down to AM.  It was a total blast beating up on many of the experts in LW in 07...Now the podiums are few and far between and I missed the chance to win a championship by just a few points.  Oh well, it's all for fun anyway at this point.

I'll keep going as long as I continue to have fun, my lap times creep down but if I plateau I may follow up on the promise to the family to hand it all up when I hit 50 (17 months).

[GSXR RACER MIKE]

The horsepower to weight argument does not work either.  I was on the track this last year with bikes that on the straights made me think my chain had fallen off.  My SV is no slouch.  This HP gap made us ride much more aggressively in the corners because that is the only place we had a chance to pass the larger bikes.  Aggressive is good to a point but the Novice rider does not need to be pushed to that level in the first year or years of racing.

Power to weight ratio (P/W/R) calculations must use the COMBINED weight of the bike (wet) AND THE RIDER to be accurate in a comparison. Different sprocket gearing can also cause changes in WHERE a certain bike and rider combination has an advantage and where they make a sacrifice (more grunt out of a turn or more top end - you only get one or the other by changing final drive ratio gearing, not both).

One mile per hour is 1.467 feet per second, so if another racer is passing you at a rate of apx 1 bike length per second their only going about 4.7 miles per hour faster than you. If your (combined weight) P/W/R is identical to theirs then they are either carrying more speed thru turns and/or their sprocket gearing is different than yours, but if their gearing was much more aggressive than yours you should catch them by the end of the straight (unless your geared to go faster than needed for that specific track). As long as a certain P/W/R can be applied to the ground, and the sprocket gearing is correct for the track, then the rest is all about the rider. BUT....If they truely do have a lower weight per Hp then your never going to be able to keep up with them if you both have similar gearing and can carry the same speed thru turns.

Here's some interesting examples:
350 lb bike + 130 lb rider = 480 lbs, divided by 85 Hp = 5.65 lbs per Hp
350 lb bike + 180 lb rider = 530 lbs, divided by 85 Hp = 6.24 lbs per Hp
350 lb bike + 230 lb rider = 580 lbs, divided by 85 Hp = 6.82 lbs per Hp

405 lb bike + 130 lb rider = 535 lbs, divided by 95 Hp = 5.63 lbs per Hp
405 lb bike + 180 lb rider = 585 lbs, divided by 95 Hp = 6.16 lbs per Hp
405 lb bike + 230 lb rider = 635 lbs, divided by 95 Hp = 6.68 lbs per Hp

405 lb bike + 130 lb rider = 535 lbs, divided by 105 Hp = 5.10 lbs per Hp
405 lb bike + 180 lb rider = 585 lbs, divided by 105 Hp = 5.57 lbs per Hp
405 lb bike + 230 lb rider = 635 lbs, divided by 105 Hp = 6.05 lbs per Hp

415 lb bike + 130 lb rider = 545 lbs, divided by 115 Hp = 4.74 lbs per Hp
415 lb bike + 180 lb rider = 595 lbs, divided by 115 Hp = 5.17 lbs per Hp
415 lb bike + 230 lb rider = 645 lbs, divided by 115 Hp = 5.61 lbs per Hp

In a race between 2 riders of similar ability, a 230 lb rider on a 415 lb 600cc middle weight bike with 115 Hp (5.61 lbs per Hp) would be almost exactly matched to a 130 lb rider on a 350 lb Lightweight bike with 85 Hp (5.65 lbs per Hp). For a bike to have 30 more Hp than another and be equalized out thru weight is a tough pill for alot of people to swallow, but it's accurate.

I would be very interested in knowing accurate Weight and Horsepower numbers for the bikes in question and the weight of the riders who are blowing past you vs. your own combined P/W/R.

[Cowboy 6]

Nice charts..... you are forgetting a little thing called torque... sorry to have to point it out.

[GSXR RACER MIKE]

Nice charts..... you are forgetting a little thing called torque... sorry to have to point it out.

Again, you gain in one area and sacrifice the other (either Hp or Torque, choose one).

If your engines highest torque is at a lower RPM it's going to have better grunt coming out of a turn and during initial acceleration but the higher RPM torque of an I-4 screamer engine is going to catch up to a torque monster engine of the same Hp (if both bikes are geared properly). If the bike / rider combination's have the same P/W/R, the bikes are geared properly, and they are both able to get that power down to the ground, then they should end up tied at the end of the longest straight. That's certainly not saying that one set-up doesn't have advantages over the other in unique applications, of course some tracks are going to be more suited overall for lower RPM grunt and others for higher RPM power (though the same Hp). If you only race at 1 track (or 1 type of track) then I'm sure you would probably see a certain engine type consistently finishing well.

Being around 1/4 mile drag racing is how I know this, online you can easily look up a '1/4 mile time and MPH calculator' and most will only ask your vehicles peak Hp and total weight (including all fluids and driver) - it doesn't care where your torque is at because as long as your vehicle is geared properly for the power delivery of the engine then at the end of the track it all works out the same (as long as you can put the power to the ground with each combination).

[HAWK]

Torque = acceleration
HP = top speed.

Yes, I4 will eat the torquey twin at the top but what this really means is that the I4 is still making good torque at the top while the twins torque is falling off. Oversimplified

HP =  Torque * RPM

The I4 can get by on less torque because it makes it over a greater band so is able to take advantage of gearing. Gearing can increase or decrease torque to the rear wheel but gearing can NEVER change HP.

Back to the topic at hand, I didn't see the 85HP 225lbs bike in your chart.

[MACOP1104]

It sounds like everyone is worried about the GP bikes.  Well, they aren't allowed in superbike and supersport so there's some salvation.  We'll see what happens if Brian Kragcet rides a GP bike at VIR.  That dude rails.

[PlayHard]

They're not gonna change the class rules.  Just race WERA on your SV and you don't need to mess with the air cooled monsters.  That's what I'm doing.  I will do some local CCS stuff and I will go to Daytona.  At the ROC, I'll only race ULWSB and maybe the LW F40.  Any other class on my SV would just be a waste of time....

I think CCS has good intentions in that they are trying to boost Grid Numbers, but I think what they are really doing is running the SV crowd off.   My plan is very similiar to yours, race WERA this coming year and throw in a couple local CCS rounds just for the fun of it. 

[roadracer162]

The 125GP bike is legal in Ultralight which is a Superbike class. Unless they are creating new Ultralight classes.

[tzracer]

Nice charts..... you are forgetting a little thing called torque... sorry to have to point it out.

More torque does not mean more acceleration. High torque at low rpm can be out accelerated by less torque at higher rpm.

Power is what determines the rate of acceleration.

As you gain speed, you also gain (kinetic) energy. The energy gained divided by the time to gain the energy is power. That is why acceleration falls off as speed increases, at higher speeds, the same change in speed requires more power because the difference in kinetic energy is not the same. Accelerating from 90 to 100mph requires 6.4 times as much power as accelerating from 10 to 20 mph in the same amount of time (not even including wind resistance) or given the same power, it would take 6.4 times longer to accelerate from 90 to 100 than 10 to 20.

2 bikes, same weight, one that is making more power will accelerate faster (assuming geared properly).

I can make the torque (rear wheel) any value I like with gearing, but the power will not change. There is an optimal gearing combination for maximum acceleration, just going to lower gearing does not always make for better acceleration.

A 100 hp engine can only do 55,000 ft-lbs of work per second regardless of the torque.

Yes, having a couple degrees in physics does help with (understanding) racing.

[Cowboy 6]

Mark,
The addition is the 250 GP bike.  That is a whole different animal.

[Burt Munro]

Gee, Professor McLaughlin, that was fun!

Now can you explain why a pound of feathers doesn't fall slower than a pound of lead ?